Environmental exposure pesticides

A recent method to screen the urine for alkyl phosphates as an indicator of exposure to organophosphate insecticides shows that the method can be used to determine environmental exposure to a specific organophosphate pesticide. The method was found to be sensitive, identifying low levels of exposure to insecticides in the environment by quantitation of urinary phosphates (Davies and Peterson 1997). The test is limited in that it is only useful for assessing recent exposure, due to the short half-life of the organophosphate pesticides. 

Case Studies in Environmental Medicine Taking an Exposure History—The importance of taking an exposure history and how to conduct one are described, and an example of a thorough exposure history is provided. Other case studies of interest include Reproductive and Developmental Hazards Skin Lesions and Environmental Exposures Cholinesterase-Inhibiting Pesticide Toxicity and numerous chemical-specific case studies. 

Dinitrophenol is a member of the aromatic family of pesticides, many of which exhibit insecticide and fungicide activity. DNP is considered to be highly toxic to humans, with a lethal oral dose of 14 to 43mg/kg. Environmental exposure to DNP occurs primarily from pesticide runoff to water. DNP is used as a pesticide, wood preservative, and in the manufacture of dyes. DNP is an uncoupler, or has the ability to separate the flow of electrons and the pumping of ions for ATP synthesis. This means that the energy from electron transfer cannot be used for ATP synthesis [75,77]. The mechanism of action of DNP is believed to inhibit the formation of ATP by uncoupling oxidative phosphorylation. 

Information on exposure levels is fundamental for the assessment and management of health risks related to occupational and environmental exposure to pesticides. Biological monitoring is a primary tool for exposure evaluation,... 

There is a growing need to better characterize the health risk related to occupational and environmental exposure to pesticides. Risk characterization is a basic step in the assessment and management of the health risks related to chemicals (Tordoir and Maroni, 1994). Evaluation of exposure, which may be performed through environmental and biological monitoring, is a fundamental component of risk assessment. Biomarkers are useful tools that may be used in risk assessment to confirm exposure or to quantify it by estimating the internal dose. Besides their use in risk assessment, biomarkers also represent a fundamental tool to improve the effectiveness of medical and epidemiological surveillance. 

Warnick SL, Eldredge JD. 1972. Human and environmental exposure to pesticides in Utah. Proceedings of the Utah Academy of Science Arts Letters 49 1972. 

Hazards Skin Lesions and Environmental Exposures Cholinesterase-Inhibiting Pesticide Toxicity and numerous chemical-specific case studies. 

Many other OECD activities on hazard/risk assessment are undertaken within programs such as Existing Chemicals, New Chemicals, and Pesticides and Biocides, which deal with specific types of chemicals. The work on exposure assessment methods is undertaken by the Task Force on Environmental Exposure Assessment, consisting of experts. Most of the outcome of this work is published in the Series on Testing and Assessment or in Emission Scenario Documents, which are available at the OECD Web site (OECD 2006a). 

Pesticide registrants must also submit environmental fate and effects data to the EPA as part of an application for pesticide registration. The EPA uses such environmental data to characterize the persistence and partitioning of a pesticide in the environment and the pesticide s environmental metabolites and degradates. This information is used by the EPA to assess the potential for human exposure via drinking water contamination and environmental exposure of organisms such as fish, wildlife, and plants to the pesticide or its metabolites. 

Assessment of human exposure to pesticides is important for a variety of reasons. In the occupational situation, it is necessary to know the amount of pesticide that an individual is exposed to in order to protect worker health. Formulators, loaders, pickers and pilots can experience high exposures to pesticides. Humans can be exposed to pesticides through environmental routes. The air we breath and the water we drink are but two sources of environmental exposure. 

Identification and prioritization of research needs at the international level would result in more focused and strategic research initiatives by both the pesticide manufacturers and the larger research community. For example, the USEPA National Exposure Research Laboratory has identified general areas of research needs in children s exposure assessments for environmental exposures (Cohen Hubal et al 2000). There is a requirement to develop harmonized priorities for research that would strengthen risk assessment methodologies for pesticides. This would need to be followed by an effective communication strategy so that funding bodies and the research community were informed about such priorities. 

One of the major concerns aroused by exposures to chemicals that affect the nervous system is their potential to adversely impact cognitive functions such as learning and memory. Such a concern certainly has precedent. Lead exposure at high levels can leave children with permanent mental retardation. Recently, it has been demonstrated that even very low levels of lead exposure (i.e., environmental exposures) can produce subtle changes in cognitive processes. Pesticides are known to exert pronounced effects on cholinergic neurotransmitter systems, the very system that has been repeatedly implicated as a causative factor in Alzheimer s disease. 

A large number of ubiquitous environmental pollutants are very toxic to the hypothalamic-pituitary-thyroid (HPT) axis when administered at high (greater than environmental) levels. To study low level effects on the HPT axis, laboratory animals were administered a mixture of 16 organochlorine pesticides and other chlorinated hydrocarbons and heavy metals, all at levels similar to those found environmentally, so as to simulate environmental exposure. The chemicals included DDT (6.91), HCB (5.73), TCDD (6.80), PCBs (6.29), methoxychlor (5.08), endosulfan (3.83), heptachlor (6.10), hexachlorocyclohexane (3.80), dieldrin (5.40), aldrin (6.50), mirex (7.18), several chlorinated benzenes (2.84-3.44), cadmium (-1.65), and lead (1.35). Effects were measured by monitoring thyroid activity. The study found that this mixture of environmental pollutants was toxic and can alter HPT physiology in sexually mature malesJ50 ... 

Virtually all human environmental exposures to toxic chemicals are to mixtures. This is particularly the case for exposures to pesticides, heavy... 

As discussed earlier, male infertility has been associated with exposures to xenobiotic chemicals. Though affects have been reported for single chemicals, most are based on laboratory testing on animals, since most environmental exposures to humans come from mixtures. Some data, however, has been collected from infertility induced by industrial and environmental exposures. Table 23.3 contains a partial list of chemicals associated with male infertility. I48,58-66 These chemicals include pesticides, heavy metals, and industrial chemicals. 

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