Survey Paper of open-source software and it's use in enterprise and Essay

Survey Paper of open-source software and it's use in enterprise and government - Essay Example Open source software enables businesses and government institutions to access and offer certain services that otherwise would have cost lots money to install and use. This survey paper aims to conduct an in depth analysis of past research literatures on the use of open source servers by enterprises and government organizations. Further, the paper analyzes how these organizations use the open source servers to efficiently perform their activities. Objectively, this survey paper seeks to relate elementary analysis of open source servers in business and government institutions as studied by other researchers in the past. Finally, the paper puts into context all the exclusion as well as inclusion results of the analyzed literature reviews about open source usage in businesses.   As a result of the widely and broad technological improvement and innovations, businesses and government organizations all over the world are in the rash to cope with these changes. It should be noted that the basic aim of any business is to maximize profit while minimizing cost. However, a successful business should also consider long term growth plans through installing an effective business operations system. On the other hand, government institutions may also want to put into place effective service delivery systems to its citizens (Bitzer & Schroder, 2006). The later considerations bring about the importance of integrating computing system into these organizations. There are different types of computer systems and some of them are more sophisticated than others. In addition, some of them have strong variance in their functionalities while others are more or less related. While business and government institutions may afford to use premium computing systems, there has been a growing demand and usage of open source servers. This reality could be attributed to the fact that some of these computing systems are free or cost effective as

Customer Strategy Development Project Research Paper

Customer Strategy Development Project - Research Paper Example According to FedEx Company Management, International Corporations are the most profitable customer groups. The group consists of international companies who purchase products from different countries to the destination industries. FedEx provides excellent transportation services for such products. Most international corporation customers are modern companies between ages less than 30 years old. Moreover, the international corporations have an extremely high-income level ranging from &50 billion Per Annum. The purchasing habit of this group is recommendable because they make massive purchases for their raw materials that require efficient transportation to the designated areas (FedEx Corporation, 2013). E-Commerce Companies forms the next group of companies served by FedEx. FedEx Company offers various services to E-Commerce companies such as mail delivery, goods transportation both locally and internationally. E-Commerce companies are of any age, and the income levels range between $ 20 billion to $30 billion per Annum. FedEx Company customer profile also caters to individual customers. Most people prefer sending emails, parcels, and other vital information via courier companies. FedEx offers services to individual adult customers over 18 years of age. In addition, individual customers can be of any sex and the income levels have less significant provided the person meets the charge requirements. The most targeted customers under the international corporations' segment include Computer and technology industries like Apple, Google, Max, and Sony. On the other hand, FedEx targets most E-Commerce companies and the rapidly growing small businesses all over the world because they offer excellent business to the company. FedEx has entered into the collaboration with OfficeMax to place its self-service drop boxes in all OfficeMax stores across the nation.

Handling Murder Scenes Investigations Criminology Essay

Handling Murder Scenes Investigations Criminology Essay Different areas tend to be prone to crime and hence the necessity of having appropriate interventions and measures which will be adopted in the handling of the murder scenes.The paper presents analyses of how law enforcers handle murder scenes and the health and legal risks associated with processing the crime scene. Conversely, it describes the strategies that should be developed by the typical law enforcement organization to improve their murder scene handling skills. Introduction Definitively, murder scene investigation refers to analytical use of physical evidence to deduce and obtain knowledge of the events surrounding the murder. This investigation is multidisciplinary and entails use of systemic search, observation and at times lab or forensic analysis of evidence. Handling and actions taken at the start of murder scene investigation plays an important role in the resolution of a case (Peterson, Mihajlovic Gilliland, 1998). A thorough investigation provides opportunities that make sure the latent physical evidence is not contaminated or likely witnesses overlooked, since if handled badly it would lead to both health and legal risks.Going by the global standards and individual country legislations, its vital for security personnels to demonstrate understanding of how to handle crime scenes (Bicheno , Elliot,1997). Personnel given a mandate of handling murder crime scenes need to have the necessary knowledge and skills that will enable them to obtain necessary evidence. Ultimately, the assessment of risk at murder scenes is an indication that anything can happen in crime scenes and its important to observe caution in order to avoid problems associated with processing of evidence. How Law Enforcement Handle a Murder Scene The great importance of carrying out murder scene investigation is to produce identification and evidence that can be used to disclose the cause of death and to obtain facts that can be used to bring the culprit to book, in case of murder. Murder scene investigation involves a meeting place of law, logic and science. Processing and handling of the murder scene is very tedious and long process that involve recognition, identification, documentation, collection of evidence and analyzing of the collected evidence. In case of suspected murder crime, law enforcers move in as investigators, where they first seal the area of murder. This is necessary to prevent contamination of the murder scene from curious onlookers. After sealing the scà ¨ne, investigators from law enforcement agency analyze the murder scene and makes sure that nothing has been moved .Here they are able to generate preliminary hypothesis based on visual examination (Bodziak, 2009). With the analysis done, the law enforcers are able to clearly describe the extent of murder crime. Apart from sealing the murder scene, the police secure the core area where they suspect a large amount of evidence is concentrated. After sealing the entire area, law enforcers then move to the district attorney s chambers where they obtain search warrants .This is important because at times some people could have prospects of privacy in portions of the murder scene. Also if not done legally, the whole investigation process would be of little importance since the findings wont be admissible in courts (Eliopulos, 2003). The law enforcers also call for any specialist and additional tools they think would be necessary during the process. The law enforcers also talk to first responders to determine if anything was moved or touched, and give details of anything they saw or heard during the occurrence of the murder crime. During this process, law enforcers touch nothing. Secondly, they scrupulously document the murder scene by taking pictures and drawing rough drafts. At times, they use video to document the scene in details without touching anything. After documenting the scene, law enforcers then engage in the collection of potential evidence, where they tag, log and package the evidence in plastic containers for laboratory analysis. The evidence is kept intact from where its transported in a safe manner for analysis. The evidence collected is labeled accordingly in relation to place of collection, date, and type of evidence collected. Before moving the body, the law enforcers analyze the body carefully for any evidence. Here they check for marks, cuts, bruises or stains on the victims body. They also check if anything is missing such as watches, rings and other personal effects (Peterson, Mihajlovic Gilliland, 1998). After collection of all evidence, the evidence is analyzed.DNA fingerprinting which is also known as forensic-DNA analysis is the common method used by law enforcers to analyze the evidence. This analysis is most reliable and affordable in such kind of scenes where for instance the body has been shot severally, burnt or even disfigured. With connection to these, the analysis provides faster mode of identification once established in such kind of scenes. Despite the benefits of dealing with DNA evidence, the evidence should not be collected unless the information is relevant to the murder crime in question. This implies that the proceedings should be undertaken under given instructions from either the regulatory bodys or the involved medical experts. Strategies of Handling Murder Scene Effectively in Relation to Law Enforcers To develop efficient strategies that would promote effective handling of murder scenes by law enforcers, it is quite necessary to have good management structures and operations within the institutions dealing with crime issues in order to promote performance within the given organization. In that case, there has been the need for different crime handling agencies to effectively adopt a number of measures that will help them in promoting teamwork and concept of working together. Problems involved in processing and handling of murder crime scenes can be mitigated by adequately training the individuals involved on better procedures and ways of handling evidence (Bodziak,2009) .As well, community involvement and awareness is also important in making sure members of the public have an idea of avoiding crime scene disturbances and dont contaminate themselves. This kind of learning and training makes sure all individuals engage in activities that do not promote murder scene and evidence con tamination.Another approach to this practice involves identification of the potential hazards which appear to be in scenes of crime and include mitigation measures which should be implemented by all.Once the problems have been identified, the next advancement is to come up with adequate plan that provide fundamental ways into how deal with exposures at the murder crime scene (Eliopulos, 2003). Issues of Law Enforcers Face in the Process of Murder Scene Investigation Many law enforcers are involved in murder scene investigations and they do encounter countless tribulations in response to how they handle evidence. For them, any action taken in the scene has some level of destructive effect on the scene and in application of justice. Sometimes scenes are degraded and altered and negative data is obtained which at times is used to convict innocent individual. Poor processing of murder scenes tends to convict innocent people and leave real culprits free and this represents injustice in the society (Bodziak,2009) Drastic changes in political and economic conditions have increased regulations and state litigation hence processing of murder crime scenes has been neglected due to strict procedural formats from the government ,as a result, individuals conducting investigations have been subjected to work without adverse training thus limiting murder scene processes. Sometimes murder crime experts like CSI personnel and law enforcers like the police, are faced with the dilemma of consulting higher authority and regulatory bodies, before conducting murder scene investigations. Indeed, this makes them loose their independence since; most of the scenes are at times thronged by curious onlookers, who have little or no knowledge of crime scene management (Bicheno Elliot, 1997). Legal inflexibility on the part of the law enforcers have contributed to challenges which force them to follow strict crime scene processing procedures which at times are time consuming and non cost effective. Investigators are required to make quick decisions even in fragile cases and legally this lead to negligence. At times there are legal problems in situations where investigators have personal stake in case. Effectiveness of the murder scene processing is lost due to the loss of neutrality in policing and close association with court systems. Other legal issues relating to murder scenes processing include technical barriers between crime scene investigators and legal practitioners. Another issue is that, an investigator may get concrete evidence to convict a criminal and yet the court disregards it. Lack of coordination between the law enforcers and courts slow down scene processing and limit justice (Peterson, Mihajlovic Gilliland, 1998). Inherent Medical and Health Risks Associated with Murder Crime Scenes, Evidence and Evidence Handling and Processing. Mostly the unintended contamination of murder scenes emerges as one of the major problems associated with murder scene handling and processing. Law enforcers involved in Murder scene investigation usually perform their works in scenes that are hazardous to their health and health of others, and this is due to coming in to contact with them. Most investigators duties entails processing of murder crime scenes and mostly they use dangerous chemicals and fingerprint powders which when accidentally ingested are life threatening. Some chemicals used are carcinogenic while others tend to cause long term Health hazards (Eliopulos, 2003). Despite the use of powders and chemicals in processing crime scenes, investigators are also susceptible to whole lots of other medical problems and hazards. Biological samples like urine, saliva, semen and blood are always handled routinely and if the victims had contagious diseases like HIV, measles and other sexually transmitted infections, probability of accidents occurring and infecting them is quiet high since majority of them have no protective clothings (Bodziak,2009) .When processing murder scenes, at times investigators use equipments like lasers, electro static dust lifters and other electrical appliances which when not handled well can cause electric shock, damage to eyes and even death. Also most law enforcers suffer from traumatic Stresses due to grotesque scenes they see when handling cases and also due to strenuous working conditions. Generally, most murder scene investigators and law enforcers are usually taken for granted and unappreciated, but they should never compromise their health (Bicheno Elliot, 1997). Conclusion Law enforcers are served with responsibility of making our community safe .They are required to investigate and arrest individuals suspected of murder crimes. Proper handling of these scenes is significant in making sure that justice has been achieved. In conclusion, Personnel given mandate of handling murder crime scenes need to have necessary knowledge and skills that will enable them to obtain necessary evidence that is indispensable in solving any murder case.

Intellectual Property :: Star Trek Trekkie Websites Essays

Intellectual Property As I begin this narrative, readers will have to understand that I have been and always will be a Trekkie. The very first movie I was ever taken to see was Star Trek III: The Search for Spock. I was six months old and I did nothing but scream the entire time, but the fascination has nonetheless been there my entire life, and there is no twelve-step program to help me recover. That having been said, you might have some degree of understanding when I say that Viacom’s attempts in 1997 to eliminate all use of copyrighted material on fan sites, ranging from still pictures to movie and sound clips to the logos themselves, was war for me. For Viacom, the issue was that these copyrighted images were used at all. This spawned a whole host of further crackdowns and lawsuits in similar kingdoms of fanatics across the web. The situation I just described to you, while probably not the best example of the internet’s general abuse of intellectual property, is one of the earliest examples. Proper accreditation and documentation is a widespread problem on the internet, particularly now that the internet has grown in use and popularity. The internet hosts websites that directly violate the concept of intellectual property in ways that no other tool ever can. If copyrighted graphics or sound appear on any website trying to convey a message, particularly if these are recognizable to an average member of the site’s target audience, the validity of that argument is subconsciously undermined by the unaccredited presence of someone else’s ideas. For web writers, one solution to this dilemma seems to be to avoid copyrighted material as much as possible and create original content. â€Å"This content does not need to be entirely dissimilar from a copyrighted work you would have liked to use. Copyright law protects the expression of ideas, not the ideas themselves† (Farkas & Farkas 349). But this solution creates problems with recreational forms of websites. Those built by fans of a popular TV show, for instance, have no personal photos of their favorite actors and actresses and inevitably rely on scanned publicity photos and content from official sites to populate their galleries and create their custom graphics. This example might then fall under the fair use defense, which â€Å"has to make the case that [use] of the copyrighted work of another should be legally permitted, notwithstanding the copyright owner's exclusive rights in her work† (George Washington).

Introduction to Personality

Introduction to Personality Paper Katie McMichael Axia College of University of Phoenix November 26, 2012 Introduction Who am I? What are my good qualities? What are my bad qualities? Why do I behave like that sometimes? Why can’t I stop doing this? How do I see myself? How do others see me? How did my personality come to be what it is today? How has it changed? When thinking about our personality, these are questions that we ask ourselves. The only way to answer these questions is to observe ourselves and analyze what we found as a result of this research.There are several theories of personality that were introduced in order to do just that. The purpose of this paper is to further understand personality and it’s concepts by defining personality, Examining theoretical approaches in studying personality, and Analyzing factors that may influence an individual’s personality development. Defining Personality Since so many theories of personality exist, there is no s ingle definition. The most widely accepted of personality is â€Å"a pattern of relatively permanent traits and unique characteristics that give consistency and individuality to a person’s behavior. (Feist & Feist, 2009) as you can see from the definition, each personality is different from each other. Also, from the definition you can see that personality is made up from the combination of characteristics and traits and serves as its base structure. Characteristics and traits are adjectives such as pretty, overweight, athletic, anxious, smart, etc. These adjectives help to give you a sense of self as well as influence your behavior. The reason that these traits and characteristics are the base structure of your personality is because they have consistency and stability in your behaviors over time. Feist & Feist, 2009) Traits have more to do with actions or physical appearance. For example, blue eyes would be considered a trait. A characteristic is merely anything that stand s out or is noticeable that can be used to describe them. For example a pitched laugh can be a characteristic. Although similar, these two parts are different, what is similar is that they work together in developing patterns what is known as your personality. People will have similar characteristics or traits that will produce similar personalities but no two personalities will ever be the same. Theoretical ApproachesAs stated earlier there are many different theories of personality. Each theorist has different methods, research and obviously conclusions as to why personalities are what they are and why they are so different from one another. One thing is certain with each theory is that a specific order of approach is important to substantiate a theory. Most theories of personalities grow from the personality of the theorist (Feist & Feist, 2009). As stated earlier, in order to get a better understanding of personalities, including your own, you must start with observations and ex perimental research.Psychologists use systematic approaches such as assessment techniques to support their hypotheses. Tests such as the Big Five Personality Test are the most valid and accurate personality assessment to date. The Big Five Personality test breaks down five areas of personalities which include dimensions such as: openness, conscientiousness, extraversion, agreeableness, and neuroticism. When it comes to other tests, the two types of validity focused upon by psychologists are construct and predictive.In construct validity â€Å"A test has construct validity if it demonstrates an association between the test scores and the prediction of a theoretical trait. †(Cherry, 2012) An example of construct validity would be an IQ test. In predictive validity â€Å"the criterion measures are obtained at a time after the test. †(Cherry, 2012) An example of this would be a career aptitude test. Both are hypothetical tests based on traits and preferences and neither wo uld be extremely accurate. These tests would be a way to get an idea of where you are and where you might end up based on your personality.Factors that Influence Personality There are two generally accepted factors that contribute to personality development which are heredity and environment. Obviously, if your traits are heretic, they were past to you through your genes from your parents and other ancestors. These traits are commonly skin color, eye color, hair color, face shape, height, and body shape. â€Å"Research by psychologists over the last several decades has increasingly pointed to hereditary factors being more important, especially for basic personality traits such as emotional tone. (Neill, 2006) This is different than what most people think. Most people seem to believe that environmental factors are substantially more influential because they have root in our morals, beliefs, and behaviors. Environmental facts that would influence personalities would be that of childh ood upbringing, learning atmospheres, social interactions, occupational interactions, and child rearing. All of these unique influences contribute to personality and even if two people have the same experiences they will respond to them different.For example men and women are different and interact and respond different usually because their upbringing is different. â€Å"Boys and girls are socialized differently to some extent in all societies. They receive different messages from their parents and other adults as to what is appropriate for them to do in life. †(Neill, 2006) It is hard to tell which factor is more influential but as you can see each one plays an important part. It doesn’t really matter what has the most influence, just important to remember that they both have influence. ConclusionWhether you take a test or just observe yourself for a while you might find out more about yourself than you knew. Observation and research are what really keeps us finding new things, why not ourselves? With a little time and effort, a person can accomplish anything. With each unique person and each personality we are doing more and learning more every day. The world never stops changing and neither do we. Our personality above all changes its face day to day from birth to death. That is what makes us unique, that is what makes us different from the animals.We have the ability to change and are smart enough to recognize it. We can define it, analyze it, study it, observe it, but our personality is always going to change as we do. In essence, our personality makes us the people that we are. References Cherry, K. (2012). What is validity? Retrieved November 26, 2012 from http://psychology. about. com/od/researchmethods/f/validity. htm Feist, J. , Feist, G. (2009). Theories of Personalities. (7th ed). New York: McGraw-Hill O’Neill, D. (2006). Personality Development. Retrieved November 26, 2012 from https://anthro. palomar. edu

Environmental Toxicology

Introduction to Environmental Toxicology A lecture by Dr Rick Leah (Long version of Notes prepared by Dr R T Leah, Biological Sciences, University of Liverpool but including material summarized and adapted from various locations on the www*) Aims The impact of toxic chemicals on wildlife and humans has been of great concern for the last fifty years. Unfortunately this is a very large, complex subject area which can only be covered superficially within the time available.However, this lecture is intended to give an introduction to fundamental aspects of how some pollutants interact with living organisms to cause deleterious effects. The complexity will be explained and simplified where possible. You should understand at least a little about the biology of key organisms and how pollutants cause damage at a physiological level. You should be aware of how pollutants can induce change in organisms which can be used as a ‘biomarker’ of the presence and action of the pollutants (although this will form the subject of a later lecture in this course).Thus as the main outcome of this lecture you should have an appreciation of the wide range of contemporary issues that are caused by toxic chemicals in the environment and what regulatory authorities are doing to monitor and control them. You should understand the main hazards that toxic chemicals pose and how risk to humans and wildlife is controlled. You should be aware of the main groups of pollutants of contemporary concern.The material covered will be useful for the consideration of two case studies on the impact of toxic chemicals in the Great Lakes of North America and the Baltic Sea in later lectures. [pic] Environmental Toxicology or Ecotoxicology? [pic] Introduction It was after World War II that increasing concern about the impact of toxic chemicals on the environment led Toxicology to expand from the study of toxic impacts of chemicals on man to that of toxic impacts on the environment. This subject became known as Environmental Toxicology.Ecotoxicology is a relatively new discipline and was first defined by Rene Truhaut in 1969. It attempts to combine two very different subjects: ecology (â€Å"the scientific study of interactions that determine the distribution and abundance of organisms† Krebs 1985) and toxicology (â€Å"the study of injurious effects of substances on living organisms†, usually man). In toxicology the organisms sets the limit of the investigation whereas Ecotoxicology aspires to assess the impact of chemicals not only on individuals but also on populations and whole ecosystems.During the early years, the major tools of Environmental Toxicology were: detection of toxic residues in the environment or in individual organisms and testing for the toxicity of chemicals on animals other than man. It was however, a very big jump in understanding from an experimental animal to a complex, multivariate environment and the subject of ECOTOXICOLOGY develop ed from the need to measure and predict the impact of pollutants on populations, communities and whole ecosystems rather than on individuals.There is an on-going debate as to the exact scope and definition of ecotoxicology. The simplest definition found to date is that ecotoxicology is â€Å"the study of the harmful effects of chemicals upon ecosystems† (Walker et al, 1996). A more complete definition of Ecotoxicology comes from Forbes & Forbes 1994 â€Å"the field of study which integrates the ecological and toxicological effects of chemical pollutants on populations, communities and ecosystems with the fate (Transport, transformation and breakdown) of such pollutants in the environment†. nd several books have been written recently which discuss this in some depth, these include: Cairns, J Jr & Niederlehner B R (1994) Ecological Toxicity Testing. CRC Press Inc: Boca Raton Forbes, V E & Forbes T L (1994) Ecotoxicology in Theory and Practice. Chapman & Hall Ecotoxicolog y Series 2: London. Walker C H, Hopkin S P, Sibly R M & Peakall, D B (1996) Principles of Ecotoxicology. Taylor & Francis: London There are three main objectives in ecotoxicology (Forbes & Forbes 1994): †¢ obtaining data for risk assessment and environmental management. meeting the legal requirements for the development and release of new chemicals into the environment. †¢ developing empirical or theoretical principles to improve knowledge of the behaviour and effects of chemicals in living systems. (More information about the highlighted terms used below can be found in the Definitions section. ) In order to achieve these objectives, the main areas of study are: The distribution of POLLUTANTS in the environment, their entry, movement, storage and transformation within the environment.The effects of pollutants on living organisms. At an individual level, TOXICANTS may disrupt the biochemical, molecular and physiological structure and function which will in turn have conseq uences for the structure and function of communities and ecosystems. At the population level it may be possible to detect changes in the numbers of individuals, in gene frequency (as in resistance of insects to insecticides) or changes in ecosystem function (e. g. soil nitrification) which are attributable to pollution.It may be possible to use BIOMARKERS to establish that a natural population has been exposed to pollution and these can provide a valuable guide to whether or not a natural population is at risk or in need of further investigation. For the purposes of the Regulation and Registration of chemicals the toxicity of individual chemicals is principally investigated via TOXICITY TESTING, the main tool of which is the Standard Toxicity Test (STT) which usually tests the DOSE or CONCENTRATION of a particular chemical that is toxic to under controlled, laboratory conditions.Toxicity tests are mainly carried out using individual animals although there has been a move towards the use of more complex systems known as MESOCOSMS. In some situations, particularly in the case of pesticides, it may be possible to carry out FIELD TRIALS to assess toxicity. Toxicity data are used to make assessments of the HAZARD and the RISK posed by a particular chemical. [pic] Significant Issues with Chemicals that have driven the development of Ecotoxicology [pic] 1. DDT – around the world 2. Cadmium in Japan 3. Mercury in Japan 4. PCBs in Japan and Taiwan 5.Dioxins – various 6. The contamination of pristine environments (eg Arctic) by atmospheric transport of organohalogens Most workers in the field of ecotoxicology refer to the publication of Rachel Carson’s Silent Spring (1962) as a landmark in the public’s awareness of potential damage to human and environmental health from man-made toxic substances. According to Rodricks (1992), Carson’s book â€Å"almost single-handedly created modern society’s fears about synthetic chemicals in the environment and, among other things, fostered renewed interest in the science of toxicology†.Certainly the consolidation of academic and related pursuits into the study of toxic substances in the environment dates from about the same time as the publication of Silent Spring. Prior to the 1960s, there were no coordinated programmes in research, in education or in regulation that systematically addressed toxic substances in the environment. Considerable progress has been made in all these areas during the past four decades. Fate of chemicals in the environment and within organisms As ecotoxicologists we are concerned with the movement and fate of toxic chemicals at both the organism level and that of the whole ecosystem.The relevant issues are: †¢ the source, †¢ transport, †¢ modification and †¢ final fate of the pollutants. At the organism level we need to be concerned with †¢ Uptake †¢ Excretion †¢ Sites of action, metabolism or storage T oxicity testing and the regulation and release of toxic chemicals As ecotoxicology largely arose from toxicology and the need to regulate the introduction of potentially toxic chemicals into the environment, toxicity testing remains central to the subject today. Most toxicity testing for pollutants is still based on tests on individual organisms in artificial test situations (see list of examples in next section).These tests are cheap, reliable and easy to perform but there is much debate about the relevance of many standard toxicity tests to ‘real life'. Initially in the early days of environmental toxicology the concept of the ‘most sensitive species' was used to relate the results of toxicity tests to the ‘real world'. Certain species in a particular community were assessed as being ‘most sensitive' to pollutants. The logic was that if a pollutant was non-toxic to the ‘most sensitive' species then it would be safe for the rest of the community.Essent ially, this logic remains today – the results of tests on single species, in artificial situations are extrapolated to predict the effects of pollutants on whole communities or ecosystems. It is assumed that if you have enough information about the effects of a pollutant on the parts of an ecosystem, then you can assemble the effects on the whole. There is however, some question about the usefulness of extrapolating from simple, highly artificial, single-species toxicity tests to complex, multi-variate ecosystems.Forbes & Forbes (1994) argue that â€Å"understanding and predicting the consequences of pollutant-induced effects on ecosystems requires that the effects be examined at the level of interest† i. e. the population, community or ecosystem. This debate has been the source of much division in ecotoxicology, between the Applied, often Industrial, Ecotoxicologists concerned with the practicalities of chemical registration and testing and the Pure or Academic Ecotox icologists who regard many toxicity testing regimes as inappropriate or at worst useless.Unfortunately, never the twain shall meet and the level of communication between the two camps has not been great. A fictional exchange makes the point well (from Forbes & Forbes 1994): â€Å"Academic Ecotoxicologist: Single species acute toxicity tests are too simplistic and have no connection with what is really going on out in nature. These standard tests are not only irrelevant and a waste of time, they may in fact do more harm than good if they lead us to believe that we can use them to adequately protect the environment when in fact we cannot.Industrial Ecotoxicologist: These tests may be oversimplified, but they are also cost-efficient, easy to perform, the procedures have been worked out, and the fact is they are required by government. We have absolutely no incentive to do more than is required by law, and, frankly, you have given us little hard evidence that current test procedures do fail to protect the environment adequately. Government Ecotoxicologist: Do you have any idea of the number of new chemicals that we have to assess each year?We can't tell industry to stop producing new chemicals and we can't wait until we understand the whole system before we try to protect it. If you think current procedures fail, then come up with some better tests – which must of course be simple, cheap and fast. Academic Ecotoxicologist: (Pause) †¦ Well, it's very complex, and of course I'll need much more data before I can give you an answer. But those single-species acute tests are oversimplified and have no connection with what is really going on out in the field †¦ Government Ecotoxicologist: We need tests! Give us tests! â€Å"The way forward for Ecotoxicology must be to integrate its two halves much more fully. Toxicity testing, using single species, do provide useful information and will almost certainly remain central to the regulation and registration of toxic chemicals but much can be done to expand the scope of toxicity testing, to add tests that apply to higher levels of organisation and so increase their relevance to the communities and ecosystems that are being protected. Testing methodologies An extensive range of ecotoxicological and biodegradation tests are required for the chemical, agrochemical and pharmaceutical industries.The tests often used include: †¢ Bacterial toxicity tests †¢ Algal Growth tests with a variety of species †¢ Acute toxicity tests with Lemna minor †¢ Acute and Reproduction tests in Daphnia magna †¢ Acute toxicity tests with the marine copepod Acartia tonsa †¢ Oyster embryo larval toxicity test †¢ Acute toxicity test with the marine invertebrate Mysidopsis bahia †¢ Earthworm toxicity tests †¢ Toxicity Tests with sediment dwelling organisms such as Chironomus or Lumbriculus †¢ Acute toxicity tests with freshwater and marine fish †¢ Bioaccumulatio n in fish †¢ Fish growth tests Early Life Cycle tests with fish Algal tests Several freshwater species are routinely tested. The most commonly used are Scenedesmus subspicatus and Pseudokirchneriella subcapitata. Other species used include Navicula Pelliculosa. Skeletonema costatum is the marine species preferred by most regulatory bodies. Electronic particle counters and size distribution analysers are used to monitor the growth of algae in the studies. Lemna is a useful substitute for higher plants. Invertebrate Tests Acute and reproduction studies are routinely conducted with Daphnia magna.Acute tests with other species are also available including the marine copepod Acartia tonsa, the freshwater sediment dwelling species Chironomus riparius or Lumbirculus variegatus and the amphipod Gammarus pulex. Fish Acute tests are conducted under static, semi-static or flow-through conditions. The choice of test regime is dependent upon the chemical properties. Tests using species comm only encountered wild in the UK are rare as most tests are conducted using species adapted for life in the laboratory including: The species used include: †¢ Rainbow trout †¢ Common carp Golden orfe †¢ Bluegill sunfish †¢ Fathead minnow †¢ Japanese killifish †¢ Zebra fish Studies can also be conducted using marine species such as Turbot and Sheepshead minnow. Definitions used in Ecotoxicology Some of the terms used in ecotoxicology, such as LD50, have simple, widely accepted definitions and hence can be defined here with some confidence. Others however vary quite widely in their interpretation from one text to another. I have tried to indicate these below and can only suggest that the reader refer carefully to the introduction of the text they are using.Where there is likely to be some contradiction I have listed the reference for the definitions given. [pic] ECOTOXICOLOGY †¢ is concerned with the toxic effects of chemical and physical agents on li ving organisms, especially on populations and communities within defined ecosystems: it includes the transfer pathways of those agents and their interactions with the environment. Butler, 1978. †¢ investigates the effects of substances on organisms. The hazard to animal and plant populations can be determined by using survey data (retrospective) or by performing specific tests (prospective).Rudolph & Boje, 1986. †¢ the science that seeks to predict the impacts of chemicals on ecosystems. Levin et al 1989. †¢ the study of harmful effects of chemicals upon ecosystems. Walker et al 1996. [pic] POLLUTANT or CONTAMINANT, XENOBIOTIC or ENVIRONMENTAL CHEMICAL? Variations of use of these terms are commonplace. â€Å"Environmental chemical† may be used to describe simply any chemical that occurs in the environment (Walker et al 1996) or substances which enter the environment as a result of human activity or occur in higher concentrations than they would in nature (Rombk e & Moltmann 1995).The terms contaminant and pollutant can be described separately but are often used as synonyms. Both words are used to describe chemicals that are found at levels judged to be above those that would normally be expected. â€Å"Pollutants† carries the connotation of the potential to cause harm, whereas contaminants are not by definition harmful. This is however, not an easy distinction to make. Whether or not a contaminant is a pollutant may depend on its level in the environment and the organism or system being considered, thus one particular substance may be a contaminant relative to one species but pollutant relative to another.Finally, in practice it is often difficult to demonstrate that harm is not being caused so that in effect pollutant and contaminant become synonymous. (Walker et al 1996). Xenobiotic is used to describe compounds that are ‘foreign' to a particular organism, that is they do not play a part in their normal biochemistry. A chemi cal that is normal to one organism may be foreign to another and so xenobiotics may be naturally occurring as well as man-made compounds (Walker et al 1996). The term Xenobiotic is sometimes also used in a more general sense to describe â€Å"foreign substances† in the environment (Rombke & Moltmann 1995). [pic]HARM or DAMAGE? Biological systems are resilient to harm caused by adverse factors in the environment since they are able to adapt to some insults. There is a fundamental difference in viewpoint between these two words, one defines harm as an effect regardless of any biological compensation that the population might make, the other defines damage as occurring only if there is an effect subsequent to any compensation. harm: biochemical or physical changes which adversely affect individual organisms' birth, growth or mortality rates. Such changes would necessarily produce population declines were it not that other processes may compensate. Walker et al 1996). damage: â⠂¬Å"the interaction between a substance and a biological system. The substance's potential to cause damage is weighed against the protective potential inherent in the biological system (e. g. excretion or metabolic reactions, adaptation or regeneration)† (Rombke & Moltmann 1995). [pic] ENDPOINTS, DOSE and CONCENTRATION There are many different ways in which toxicity can be measured but they are usually assessed relative to a particular outcome or END POINT. Initially, most Toxicity Tests measured the number of organisms killed by a particular DOSE or CONCENTRATION of the chemical being tested.With terrestrial animals the DOSE of chemical (taken orally, applied to the skin or injected) administered is usually recorded. DOSE is usually used where the dietary dose of a test chemical can be accurately determined. For aquatic organisms or where the test chemical is dosed into the surrounding medium, the tests usually measure the CONCENTRATION of chemical in the surrounding water/me dium. The following measures, known as a group as EDs or ECs (Effective Doses or Effective Concentrations) are frequently used to describe data from toxicity tests: LD50Median lethal dose, that is the dose that kills 50% of the population LC50 Median lethal concentration. ED50/EC50 Median effect dose/concentration, that is the dose that produced a defined effect to 50% of the population. NOED/NOEC No Observed Effect Dose (or Concentration) NOEL No Observed Effect Level. Sometimes this more general term is used to describe either of the above. It can be defined as the highest level (that is dose or concentration) of the test chemical that does not cause a statistically significant difference from the control. LOED/LOE Lowest Observed Effect Dose (or Concentration)There has been a move away from the use of lethal end points in toxicity testing towards the measurement of EFFECTS rather than death. Examples of EFFECTS which can be used include changes in: reproduction (eg. number of egg s laid or young hatched); growth (e. g. biomass or body length) and biochemical or physiological effects (e. g. enzyme synthesis or respiration). [pic] HAZARD AND RISK Toxicity data is used to make assessments of the HAZARD and the RISK posed by a particular chemical. Where: HAZARD is the potential to cause harm RISK is the probability that harm will be caused.Defining HAZARD involves answering two questions, ‘how much damage are we prepared to tolerate' and ‘how much proof is enough'. The first is a question for society, alleviating/avoiding/repairing damage involves costs, how much are we prepared to pay? The second is largely a scientific problem of providing sufficient evidence that damage is due to pollution. HAZARD is not necessarily directly related to toxicity, it is a product of exposure and toxicity, a compound with moderate toxicity but very high exposure may cause more damage that a very toxic chemical with very low exposure.RISK is usually defined using the predicted environmental concentration (PEC) and the predicted environmental no effect concentration (PNEC). Information on the movement and behaviour of pollutants in the environment are used to calculate the PEC whereas data from Toxicity Testing must be extrapolated to calculate the PNEC. The making of these calculations is not a precise art, apart from doubts about the extrapolation of Toxicity data from the lab to the field it can be very difficult to estimate the degree of exposure, particularly for mobile taxa such as birds and mammals. [pic]BIOMARKERS A Biomarker can be defined as a â€Å"biological response to a chemical or chemicals that gives a measure of exposure and sometimes, also, of toxic effect† (Walker et al 1996), they can be divided into biomarkers of exposure and of toxic effect. Examples of biomarkers range from the inhibition of AChE (acetylcholinesterase) in the nervous system of animals to the thinning of eggshells in birds. Biomarkers can help to brid ge the gap between the laboratory and the field by giving direct evidence of whether or not a particular animal, plant or ecosystem is being affected by pollution.They will often provide more reliable evidence of exposure than measurements of the pollutants themselves in the environment, the latter are often short-lived and difficult to detect, whereas their effects (detectable via biomarkers) may be much longer-term. [pic] A QUESTION OF SCALE AND ACCURACY The difficulty in extrapolating from simple, highly artificial, single-species toxicity tests to complex, multi-variate ecosystems has led to attempts to develop more complex systems which can be used in toxicity tests.Such systems are usually termed microcosms, mesocosms or macrocosms, that is small, medium or large multispecies systems. It must be possible to control conditions in these systems to such an extent that they can provide meaningful, reproducible (that is, the system could be accurately copied elsewhere), replicable (that is, two replicates of the same experiment would produce the same results) data in toxicity tests. Simply because they are more complex systems it is seldom possible to produce tests that are as precise and controlled as those carried out in single species STTs.However, despite their limitations these larger-scale tests can provide important insights into the effect of pollutants on whole systems rather than on single species. [pic] MIXTURES OF CHEMICALS, ADDITION OR MULTIPLICATION? In natural systems, organisms are often (usually) exposed to more than one pollutant at the same time. However, regulatory authorities usually assume – unless there is evidence to the contrary – that the toxicity of combinations of chemicals is roughly additive.Fortunately in many cases this is quite correct but in some cases, toxicity is more than additive in that is there is POTENTIATION of toxicity. One particular type of potentiation called SYNERGISM occurs where the effect of two or more chemicals combine to have greater impact than expected from their individual concentrations. [pic] Ecotoxicology – Pesticide Definitions [pic] What is a pesticide? A literal definition of a pesticide would be â€Å"a killer of pests†. In practice pesticides are no longer aimed exclusively at killing the pests they are used to control and the term has acquired a rather wider meaning uch as â€Å"the chemical tools used to manage all kinds of pests† or in the US it's more official definition is â€Å"any substance used for controlling, preventing destroying, repelling or mitigating any pest† (all definitions from Ware 1991). Hence pesticides include not only those chemicals which kill the pest they are used against but also those such as insect chemosterilants or plant and insect growth regulators which control pest populations without necessarily, physically, killing the pests they come into contact with.Pesticides have been divided into many diffe rent classes. Firstly, according to the target organism that they control, so insect-icides kill (or control) insects, rodent-icides control rodents etc. The -icide suffix has been widely used in the past, as shown in Table 1, but relatively few of these terms are in common use today. Secondly, pesticides can be classified according to their mode of action, that is the way in which they act on the pest population, e. g. attractants, repellents, chemosterilants etc.Finally, the definition of a pesticide has been widened once again to: â€Å"pesticides are used by man as intentional additions to his environment in order to improve environmental quality for himself, his animals or his plants† (Ware 1991). This definition allows the inclusion of 2 new classes of treatment. Firstly those such as plant growth regulators, which are not only used as herbicides to control weeds, but also to control directly the growth of the crop and hence improve its success.For instance, they are us ed to reduce the growth of cereals so that they do not become too tall and prone to ‘lodging' before harvest. Secondly, microbial pesticides which are not based on a chemical but on bacteria, fungi, nematodes and viruses which attack the pest. [pic] Table 1 Classes of pesticide according to : A. the target organism and B. pesticide mode of action. After Ware (1991). |CLASS |FUNCTION | |A.By Target Organism   | |acaricide |kills/controls mites | |algicide |kills/controls algae | |avicide |kills/controls or repels birds | |bactericide |kills/controls bacteria | |fungicide |kills/controls fungi | |herbicide |kills/controls plants | |insecticide |kills/controls insects | |larvicide |kills/controls larvae (usually mosquitoes) | |miticide |kills/controls mites | |molluscicide |kills/controls snails & slugs.May include oysters, clams, & mussels | |nematicide |kills/controls nematodes | |ovicide |kills/controls eggs | |pediculicide |kills/controls lice | |piscicide |kills/c ontrols fish | |predicide |kills/controls predators (usually such as coyotes) | |rodenticide |kills/controls rodents | |silvicide |kills/controls trees & brush | |slimicide |kills/controls slime | termiticide |kills/controls termites | |B. By Mode of Action – by affect on pest   | |attractants/pheromones |Attract animals, especially insects usually into traps. Often sexual pheromones. | |chemosterilants |Sterilise insects or vertebrates (birds, rodents). Usually sterilise males. | |defoliants |Remove leaves. | |desiccants |Speed drying of plants. Used not only to kill weeds but also as pre-harvest desiccants to make harvesting | | |easier. |disinfectants |Kill or inactivate harmful micro-organisms | |feeding stimulants |Cause insects to feed more vigorously | |growth regulators |Stimulate or retard plant or insect growth. Natural or artificial hormones used not only to kill weed species | | |but also to protect crops such as cereals from lodging. | |repellents |Repel insects, mites, ticks or pest vertebrates (dogs, rabbits, deer, birds). | |B. By Mode of Action – by timing of application | |curative (fungicides) |applied to the plant after initial infection. |eradicant (fungicides) |applied when disease symptoms have already become visible, often to prevent the spread of disease. | |protectant (fungicides) |applied to the plant surface before infection. | |pre-plant or pre-sowing |applied before crop is sown or planted | |(herbicides) | | |pre-emergence (herbicides) |applied before the crop has germinated | |post-emergence(herbicides) |applied after the crop has germinated | |B.By Mode of Action – by selectivity | |the degree to which a pesticide discriminates between target and non-target organisms. | |selective |A selective pesticide effects a very narrow range of species other than the target pest or may be. The chemical | | |itself may be selective in that it does not affect non-target species or it may be used selectively in such a | | |way that non-target species do not come into contact with it. | |non-selective |a non-selective pesticide kills a very wide range of plants, insects, fungi etc. | |B.By Mode of Action – by site of interaction with pest | |systemic |the pesticide is absorbed by the pest and moves around within the pest system to reach parts of the pest remote | | |from the point of application | |contact |contact pesticides directly affect the parts of the plant, insect, fungus etc to which they are applied. They | | |cause localised damage to the plant or animal tissue on contact. | References Barlow, F (1985) Chemistry and formulation. In: Pesticide Application: Principles and Practice. Ed: P T Haskell. Oxford Science Publications: Oxford. pp 1-34. Dent, D R (1995) Integrated Pest Management.Chapman & Hall: London, Glasgow, Weinheim, New York, Todyo, Melbourne, Madras. Rombke, J & J M Moltmann (1995) Applied Ecotoxicology. Lewis Publishers: Boca Raton, New York, London, Tokyo. Wa re, G W (1991) Fundamentals of Pesticides. A self-instruction guide. Thomson Publications: Fresno USA. [pic] Ecotoxicology – Pesticide Classification – Insecticides [pic] While pesticides can be divided into many classes by target organism, mode of action etc for most purposes chemical pesticides are divided into three major groups according to their target organism, that is: insecticides, herbicides and fungicides. These groups are then subdivided into chemical groups such as organophosphates, organochlorines, carbamates etc.This simplified classification effectively groups acaricides, nematicides and molluscicides in with insecticides as many chemicals that have acaricidal, nematocidal or molluscicidal properties are also insecticidal. The current proliferation of chemical insecticides dates from World War II, until this time the insecticides available were based on: arsenicals, petroleum oils, sulphur, hydrogen cyanide gas, cryolite and on extracts from plants such as pyrethrum, nicotine and rotenone. Table 2: Classification of Insecticides gives a summary of the main chemical classes of insecticide and the main chemicals in each class. The characteristics of the main classes of insecticide: the organochlorines, organophosphates, carbamates and pyrethroids are summarised below. Organochlorines Also called: chlorinated hydrocarbonsA large and varied group that has a particularly high public profile because of the environmental problems they have caused. They were mostly discovered in 1942-56 and were very important in the early success of synthetic insecticides. They are mostly Insecticides with a very wide range of actions, they can be divided into three main groups: DDT and related compounds including rhothane (DDD) and methoxychlor. Widely used during World War II for control of disease vectors (such as mosquitoes) and subsequently much used on agricultural pests such as ectoparasites of farm animals and insect disease vectors and also widel y used against insects in domestic and industrial premises. chlorinated cyclodiene insecticides such as aldrin, dieldrin and heptachlor. ost widely used as seed dressings and soil insecticides. hexachlorocyclohexanes (HCHs), such as lindane used against pests and parasites of farm animals, also in insecticidal seed dressings. Organochlorine insecticides are very stable solids with: limited vapour pressure, very low water solubility and high lipophilicity. They may be very persistent in their original form or as stable metabolites. They tend to be stored in body fats and are particularly hazardous because they are so stable and tend to accumulate in successive organisms in the food chain. DDT and the HCHs a regarded as only moderately toxic to mammals while the chlorinated cyclodienes are highly toxic.Action: all organochlorine insecticides are nerve poisons but DDT has a different action to the chlorinated cyclodienes and HCHs. DDT acts on the sodium channels in the nervous system s o that the passage of an ‘action potential' along the nerve is disrupted. It causes uncontrolled repetitive spontaneous discharges along the nerve. Uncoordinated muscle tremors and twitches are characteristic symptoms. The chlorinated cyclodienes and HCHs act on the GABA receptors which function as a channel for Cl – ions through the nerve membranes. They bind to the GABA receptors and reduce the flow of Cl – ions. Typical symptoms include convulsions. Organophosphates Also called: organic esters of phosphorus acid.Such as bromophos, chlorpyrifos, diazinon, dichlorvos, fenitrothion, malathion, parathion and phorate. The same basic constituents are combined with many additional chemicals to give a wide range of products with very different properties. Organophosphates were developed during the second world war and have two main uses: as insecticides and as nerve gases (chemical warfare agents). They are mostly liquids, liphophilic, with some volatility and a few a re solids. Generally, they are less stable and more readily broken down than organochlorines and are relatively short-lived in the environment, hence most of their hazard is associated with short-term (acute) toxicity.The water solubility of the various organophosphate compounds is very variable and they are prepared in numerous formulations: as emulsifiable concentrates for spraying and to control ectoparasites of farm animals (particularly sheep dips) and sometimes internal parasites (such as ox warble fly); as seed dressings and as granular formulations particularly used for the most toxic organophosphates (e. g. disyston and phorate) as the active ingredient is effectively ‘locked up' in the granule and is safer to handle and only slowly released into the environment. Organophosphates are also used to control vertebrate pests such as Quelea in Africa. Action: like organochlorines, organophosphates also act as a neurotoxin. They combine with the enzyme acetylcholinesterase and prevent conduction of nerve impulses at junctions in the nervous system where acetylcholine is the natural transmitter.As a result, acetylcholine builds up in the nerve synapse and eventually leads to synaptic block when the acetylcholine can no longer relay signals across the synapse. In neuro-muscle junctions this leads to tetanus, the muscle is in a fixed state, unable to contract or relax in response to nerve stimulation. Carbamates e. g. aldicarb, carbaryl, carbofuran, methiocarb, methomyl, pirimicarb and propoxur Carbamates are a more recent development than organochlorines or organophosphates, they are all derivatives of carbamic acid. The basic carbamate group is combined with different chemicals to produce insecticides with a wide range of properties (in particular they vary greatly in their water solubility) and actions.Carbamates are not only used as insecticides but also molluscicides and nematicides. Carbamates are also used as herbicides and fungicides but these ha ve a different mode of action and are described elsewhere. Carbamates are mainly used to control insect pests in agriculture and horticulture, they have abroad spectrum of activity and usually act by contact or stomach action although a few possess systemic activity (aldicarb, carbofuran). Action: basically the same as organophosphates, inhibiting the action of acetylcholine at the nerve synapses. Doses of carbamates are not accumulative and carbamate poisoning is more easy to reverse than that caused by organophosphates.They are generally regarded as representing a short-term hazard. Pyrethroids Such as cypermethrin, deltamethrin, permethrin, phenothrin, resmethrin. Pyrethrin insecticides were developed from naturally occurring chemicals found in the flower heads of Chrysanthenum sp. and these provided the model for the production of synthetic pyrethroid insecticides. Pyrethroids are generally more stables than natural pyrethrins. The development of pyrethroids can be traced over 4 main phases (Ware 1991). The first generation allethrin was a synthetic duplicate of a natural pyrethrum, cinerin I. The second generation included bioallethrin, phenothrin, resmethrin and bioresmethrin.These were marginally more effective than natural pyrethrums but were neither effective enough nor photostable enough to be used extensively in agriculture. However, they are still used in pest control formulations for the home. The third generation of pyrethroids included fenvalerate and permethrin which were stable in sunlight and only slightly volatile and could be used successfully in agriculture. Finally, the fourth and current generation of pyrethroids can be used at much lower concentrations (one-fifth to one-tenth) that those in generation 3 and are all photostable. Overall, most pyrethroids are not sufficiently soluble in water to be used a systemic insecticides. They are mainly formulated as emulsifiable concentrates for spraying.They control a wide range of agricultural a nd horticultural insect pests and are used extensively to control insect vectors of disease (e. g. tsetse fly in Africa) Action: pyrethroids are generally solids with very low water solubility and they act as neruotoxins in a very similar way to DDT. They are readily biodegradable but can bind to particles in soils and sediments and can be persistent in these locations. They are particularly toxic to insects as opposed to mammals and birds and the main environmental concerns are over their effects on fish and non-target invertebrates. Table 2: Classification of Insecticides Data from: Whitehead, R (1995) The UK Pesticide Guide. CAB International & BCPC. Chemical group |Compound |Action |Notes | |AMIDINES | | | | |   |amitraz |   |also ACARICIDE | |BOTANICAL | | | | |   |azadirachtin |insect growth regulator |extracted from Neem | |   |nicotine |contact, non-persistent general |extracted from tobacco | | | |purpose, | | |   |pyrethrin |contact, non-persistent |extracted from Pyrethrum | |   |rotenone |contact |extracted from Derris and Lonchocarpus | |CARBAMATES | | | |   |aldicarb |systemic |also NEMATICIDE | |   |bendiocarb |contact & ingested |   | |   |carbaryl |contact |also WORM KILLER, FRUIT THINNER | |   |carbofuran |systemic |also NEMATICIDE | |   |methiocarb |stomach acting |also MOLLUSCICIDE | |   |methomyl |fly bait |   | |   |pirimicarb |contact & fumigant aphids only |   | |   |propoxur |fumigant, maimainly in |   | | | |glasshouses | | |   |thiocarb |pelleted bait |also MOLLUSCICIDE | |ORGANOCHLORINES | | | | |diphenyl aliphatic derivatives |DDT |   |   | |   |rhothane (DDD) |   |   | |benzene derivatives |lindane ? amma HCH |contact, ingested & fumigant |   | |cyclodiene derivatives |aldrin |persistent |UK revoked 1989 | |   |dieldrin |persistent |UK revoked 1989 | |   |endosulfan |contact & ingested |also ACARICIDE | |ORGANOPHOSPHATES | | | | |aliphatic derivatives |dichlorvos |contact , fumigant    | |   |dimethoate |contact, systemic |also ACARICIDE | |   |disulfoton |systemic, granules |   | |   |malathion |contact |also ACARICIDE | |   |phorate |systemic |   | |phenyl derivatives |fenitrothion |contact, broad spectrum |   | |   |parathion |   |   | |heterocyclic derivatives |chlorpyrifos |contact & ingested |also ACARICIDE | |   |diazinon |contact |   | |ORGANOTINS | | | | |   |fenbutatin-oxide |   |ONLY ACARICIDE | |PYRETHROIDS | | | | |generation 1 |allethrin |   |   | |generation 2 |bioresmethrin |contact, residual |also ACARICIDE | |   |phenothrin |contact & ingested |   | |   |resmethrin |contact |   | |   |tetramethrin |contact |   | |generation 3 |fenvalerate |contact |   | |   |permethrin |contact & ingested, broad |   | | | spectrum | | |generation 4 |bifenthrin |contact, residual |also ACARICIDE | |   |cypermethrin |contact & ingested |   | |   |cyfluthrin |   |   | |   |fenpropathrin |contact & ingested |also ACARICIDE | [pic] Ecotoxicology – Pesticide Classification – Herbicides [pic] It is really only in the last 50 years that use of chemical weedkillers or herbicides has become widespread. Prior to this, the control of weeds in crops was carried out largely by manual weeding, crop rotation, ploughing and various ways of stopping weed seeds being dispersed in crop seed. Today, the heavy use of herbicides is confined to those countries that practice highly intensive, mechanised farming.In 1971 it was estimated that more energy was expended on weeding crops than on any other single human task (Brain 1971 ). Herbicides are also used extensively in non-crop and amenity situations such as industrial sites, roadsides, ditch banks, recreational areas etc. Herbicides can be classified in a number of different ways. The main classification used is often according to chemical class but they can also be classified according to their selectivity, the way th at they affect the plant, the timing of application and the area covered by an application. Herbicides are classed as selective if they kill some plant species but not others, for instance they may kill the weeds but not the crop and as non-selective if they kill all vegetation.Herbicides may be intrinsically selective in that they are active against some species of weed but not others but they may also be used selectively, that is in such a way that they only come into contact with the weeds and not the crop. There are two main ways in which herbicides affect the plants they are applied to: contact herbicides kill parts of the plant that they come into contact with. These are generally used against annual weeds and if they are to be effective need complete coverage of the target weed with the chemical. Systemic or translocated herbicides are absorbed either by the roots or foliage of the plant and then move within the plants system to areas remote from the site of application.Trans located herbicides tend to be slower acting than contact ones and while they can be used against annual weeds they are more commonly aimed at perennial weeds. With translocated herbicides a uniform, although not necessarily complete, coverage of the target weeds is necessary. Finally, herbicides can be classified according to the timing of application in relation to the crop they are being used in. Pre-plant, or pre-sowing herbicides must be applied to an area before the crop is planted. Pre-emergence herbicides are applied before the crop has emerged, this may allow an added level of selectivity as a herbicide can be applied to growing weeds while the crop itself is still protected by the oil. Finally, post-emergence herbicides are applied after the crop has emerged from the soil.Again, a level of selectivity may be introduced by applying a germination inhibitor to prevent further germination of weed seeds – after the crop itself has germinated. Phenoxy Herbicides e. g. 2,4- D, MCPA, 2,4,5-T All derivatives of phenoxyalkane carboxylic acids that act as plant growth regulator herbicides. Phenoxy herbicides were the first safe, selective herbicides discovered and they are still used in huge quantities. They act by simulating the action of natural hormones and produce uncoordinated plant growth. Their action is selective as they are toxic to dicotyledonous but not monocotyledonous plants. Hence they can be used to control ‘dicot' weeds (broad leaved weeds) in ‘monocot' crops (e. g. cereals, grass). Their physical properties vary greatly according to formulation.For instance, as alkali salts they are highly water soluble (can be formulated as aqueous solutions) whereas when as simple esters they have low water solubility and are lipophilic (generally formulated as emulsifiable concentrates). The main hazard they present is mainly posed by unwanted spray drift but they have also sometimes been contaminated with the highly toxic compound TCDD (or dioxin). Other related compounds, also with plant growth regulating properties include phenoxypropionic acids (e. g. CMPP) and phenoxybutyric acids (e. g. 2,4DB). Table 3: Classification of Herbicides Data from: Whitehead, R (1995) The UK Pesticide Guide. CAB International & BCPC. Chemical group |Compound |Uptake/action |Persistence |Timing/site of |Other uses | | | | | |application | | |ACETANILIDES | | | | | | |   |alachlor |via roots, |residual |pre/post-emergence |   | | | |translocated | | | | |AMIDES or substituted amides | | | | | | |   |napropamide |   |   |pre-emergence |   | |   |propachlor |   |   |pre-emergence | |BENZOICS or arylaliphatic acids | | | | | | |   |dicamba |translocated |   |soil/foliar |   | |BENZONITRILES or substituted nitriles| | | | | | |   |dichlobenil |   |residual |soil |   | |DIAZINONES | | | | | | |   |bentazone |contact |   |post-emergence |   | |BIPYRIDYLIUMS | | | | | | |   |diquat |contact |non-residual |f oliar |pre-harvest, CROP | | | | | | |DESICCANT | |   |paraquat |contact |non-residual |   |   | |CARBAMATES or carbanilates | | | | | | |   |asulam |translocated |   |foliar |   | |   |chlorpropham |   |residual |soiltubers |POTATO SPROUT SUPPRESSANT| |   |phenmedipham |contact |   |foliar |   | |CHLOROALKANOIC ACIDS or chlorinated | | | | | | |aliphatic acids | | | | | | |   |dalapon |   |persistent |soil? | |DINITROANILINES or nitroanilines | | | | | | |   |pendimethalin |   |residual |pre-emergence, soil|   | |   |trifluralin |   |   |soil-incorporated |   | |HBNs | | | | | | |   |bromoxynil |contact |   |post-emergence |   | |   |ioxynil |contact |   |post-emergence |   | |IMIDAZOLINONES or imidazoles | | | | | | |   |imazapyr |translocated |residual |foliar, soil |   | |   |imazaquin |   |   |   |   | |OXIMES or cyclohexenones | | | | | | |   |cycloxydim |translocated |   |post-emergence |   | |   |setho xydim |   |   |post-emergence |   | |PHENOXYACETIC ACIDS | | | | | | |   |MCPA |translocated |   |post-emergence |   | |PHENOXYBUTYRIC ACIDS | | | | | | |   |MCPB |translocated |   |post-emergence |   | |PHENOXYPROPRIONIC ACIDS | | | | | |   |diclofop-methyl |translocated |   |post-emergence |   | |   |fenoxaprop-P-ethyl |   |   |post-emergence |   | |   |fluazifop-P-butyl |   |   |post-emergence |   | |   |mecoprop |translocated |   |   |   | |   |mecoprop-P |translocated |   |post-emergence |   | |PHOSPONIC ACIDS or phosphona amino | | | | | | |acids or phosphates | | | | | | |   |glufosinate-ammonium |contact |non-residual |foliar |   | |   |glyphosate |translocated |non-residual |foliar |   | |PICOLINIC ACIDS | | | | | | |   |picloram |translocated |persistent |foliar, soil |   | |PYRIDINOXY ACIDS | | | | | | |   |fluroxypur |   |   |post-emergence |   | |   |triclopyr |   |   |foliar |   | |QUATER NARY AMMONIUM | | | | | | |   |difenzoquat |   |   |post-emergence |   | |SULFONYLUREAS | | | | | |   |metsulfuron-methyl |contact |residual |post-emergence |   | |   |triasulfuron |   |   |post-emergence |   | |THIOCARBAMATES | | | | | | |   |tri-allate |   |   |soil-acting, |   | | | | | |pre-emergence | | |TRIAZINES | | | | | | |   |atrazine |   |residual |pre/post emergence |   | |   |cyanazine |contact |residual |pre-emergence |   | |   |metribuzin |contact |residual |pre-/post-emergence|   | |   |simazine |root uptake |   |soil