Pesticide detecting exposure

In most of developed countries, programs to monitor the presence of pesticides in the environment are being carried out, dealing with air, water and soil contamination. These programs detect exposures to pesticides or other chemicals that are likely to cause disease. The goal for public health agencies is to obtain the amounts of these pesticides that are to be found in the population [21]. 

Antemortem Blood 5-10 ml Useful for detecting exposure to most metals, trace elemerns, chofinesterase, pesticides, and ethylene glycol, and for evaluating erythrocyte and leukocyte moiphology... 

Agarwal et al. 1978), the quantification of these specific enzymes may indicate that exposure to endosulfan has occurred. Blood tests, such as decay curves for aminopyrine in plasma, which are semiquantitative indices of liver enzyme induction, have been used successfully in the past to demonstrate enzyme induction in pesticide-exposed workers. Because numerous chemicals found at hazardous waste sites also induce these hepatic enzymes, these measurements are not specific for endosulfan exposure. However, measurements of enzyme activity, together with the detection of the parent compound or its metabolites in tissue or excreta, can be useful indicators of exposure. All of these potential biomarkers require further verification in epidemiological studies. Further studies with focus on the development of methods to separate and measure the estrogenicity of endosulfan in in vitro assays would be valuable since these assays are more sensitive and discriminative than other conventional biomarkers. Preliminary results have been presented by Sonnenschein et al. (1995). 

Today, when a pesticide with no detectable residues is registered for use, a Tolerance or maximum residue limit (MRL) is established at the lowest concentration level at which the method was validated. However, for risk assessment purposes it would be wrong to use this number in calculating the risk posed to humans by exposure to the pesticide from the consumption of the food product. This would be assuming that the amount of the pesticide present in all food products treated with the pesticide and for which no detectable residues were found is just less than the lowest level of method validation (LLMV). The assumption is wrong, but there is no better way of performing a risk assessment calculation unless the limit of detection (LOD) and limit of quantification (LOQ) of the method were clearly defined in a uniformly acceptable manner. 

A method for determining the LOD and LOQ for water samples was proposed by the US EPA. This method has also been discussed by Roy-Keith Smith in his book titled Handbook of Environmental Analysis .The method has also been proposed by the US EPA in their guidelines for Assigning Values to Non-detected/Non-quantitied Pesticide Residues in Human Health Pood Exposure Assessments . ... 

US EPA, Assigning Values to Non-detected/Non-quantified Pesticide Residues in Human Health Food Exposure Assessments, Guidance Document Office of Pesticide Programs, US Environmental Protection Agency, Washington, DC (March 23,2000). Also available on the World Wide Web http //www.epa.gov/pesticides/trac/science/trac3b012.pdf. 

CL95 = 0.008-0.28 qgg ). Diazinon concentrations in earthworm samples were higher p < 0.005) in PA orchards, where rainfall was frequent, than in the more arid WA orchards. This difference also existed for live captured earthworms from PA and WA p < 0.017). A large number of samples are required to detect differences in pesticide exposures from living and dead invertebrates with confidence. Vertebrate exposures can be influenced by differential residue concentration for living and dead/moribund food items. 

Distributions of pesticide concentrations in potential food items for avian species are required to estimate the contribution of food to exposure of birds in different regions where the test chemical may be used. On treated fields, detectable CEF residues were found in 102 of 207 earthworm samples. No earthworm samples collected from control fields (N = 28) contained detectable CEF. Average CEF concentrations in earthworms reached maxima 1-4 days post-application (Table 3). Mean CEF residues in earthworms fell below 0.1 qg g after 8 days post-application. This... 

Besides alkylphosphates, OP metabolism gives rise to the production of other metabolites that can be used as exposure markers (Table 4). Unchanged OP compounds in blood or urine can also be measured to confirm exposure (Table 4), but this method is of limited use for routine biological monitoring of occupational exposure, as OP compounds are rapidly excreted in urine. Moreover, most OP pesticides are unstable, and, with a few exceptions, they are not detectable in biological specimens after a few hours. So far, the measurement of unchanged compounds in biological fluids has been performed primarily for research purposes and has limited practical applicability. 

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