Biomonitoring pesticide exposure

Pesticide exposure assessment Jazzercize activities to determine extreme case indoor exposure potential and in-use biomonitoring... 

The AHS, a collaborative research effort between the National Cancer Institute of the National Institutes of Health and EPA, is a prospective occupational study of 89,658 pesticide appliers and their spouses in Iowa and North Carolina assembled between 1993 and 1997 to evaluate risk factors for disease in rural farm populations (Blair et al. 2005). It is being conducted in three phases—phase I (1993-1997), phase II (1999-2003), and phase III (2005)—and includes only limited biomonitoring. Data are gathered with questionnaires to determine pesticide use and exposures, work practices, and other relevant exposures from buccal cell collection with dietary surveys and with interviews to determine updated pesticide exposures (Agricultural Health Study 2005). 

Conducted by the University of Minnesota, the FFES is a study of pesticide workers that includes limited biomonitoring. About 95 farm families in Minnesota and South Carolina are involved in regular monitoring of pesticide exposure (Farm Family Exposure Study 2005). After pesticide exposure at the farms, urine samples are collected for 24 hours/day for 4 days. A baseline 24-hour sample is collected before pesticide application. The study is expected to improve exposure assessment in epidemiologic studies of agricultural populations (Baker et al. 2005). 

Baker, B.A., B.H. Alexander, J.S. Mandel, J.F. Acquavella, R. Honeycutt, and P. Chapman. 2005. Farm Family Exposure Study Methods and recruitment practices for a biomonitoring study of pesticide exposure. J. Expo. Anal. Environ. Epidemiol. 15(6) 491-499. 

The committee recommends the inclusion of a detailed and accurate exposure analysis for a subset of the biomonitored population in large-scale biomonitoring studies that includes analyses of environmental media in the residence and uses a survey instrument to obtain information on diet, consumer product use, occupational exposures, and other factors relevant to the chemical exposure pathways that are being examined. The exposure assessment can be patterned on protocols used in other exposure analyses, such as the National Human Exposure Assessment Survey (NHEXAS), the Minnesota Children s Pesticide Exposure Study, and Children s Total Exposure to Pesticides and Other Persistent Organic Pollutants. 

Pesticide Exposure Assessment, Biomonitoring, Pyrethroid, Situational Monitoring... 

Table 3 Estimates of Human Exposure Derived from Whole-Body Dosimetry, Biomonitoring, and Routine Use of Pesticide Fogger...

Presently available methods to diagnose and biomonitor exposure to anticholinesterases, e.g., nerve agents, rely mostly on measurement of residual enzyme activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in blood. More specific methods involve analysis of the intact poison or its degradation products in blood and/or urine. These approaches have serious drawbacks. Measurement of cholinesterase inhibition in blood does not identify the anticholinesterase and does not provide reliable evidence for exposure at inhibition levels less than 20 %. The intact poison and its degradation products can only be measured shortly after exposure. Moreover, the degradation products of pesticides may enter the body as such upon ingestion of food products containing these products. 

A majority of U.S. biomonitoring efforts measure such analytes as heavy metals, pesticides, cotinine, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins, phthalates, and volatile organic compounds (VOCs). Future population-based studies (such as NHANES) will include such chemicals as perfluorinated compounds, polybrominated diphenyl ethers (PBDEs), and perchlorate, on which little exposure information is available. 

The RMBC assessed its regional public-health priorities and developed the following nine demonstration projects on the basis of the needs of the community possible correlation of exposure to arsenic in drinking water and type 2 diabetes, a spot blood metals-analysis feasibility study, health-clinic samples for chemical-terrorism baselines, of relationship between urine arsenic and metal concentrations and drinking-water exposure, assessment of exposure to VOCs from subsurface volatilization, cotinine concentrations associated with environmental tobacco smoke, assessment of exposure to mercury from ingestion of fish, analysis of radionuclides in urine, and biomonitoring of organophosphorus pesticides in urine (Utah Department of Health 2006). 

Appendix B provides brief case studies of two pesticides, glyphosate and permethrin, for which a pre-existing risk assessment can help to put biomonitoring results into perspective. In both cases, the Environmental Protection Agency (EPA) has evaluated risks for a wide array of exposure scenarios as part of the reregistration process, and there are biomonitoring data whose interpretation could benefit from these risk assessments. 

It can assess in utero exposure. Any substance in the maternal circulation can be transferred across the placenta to the developing fetus unless it is first metabolized and eliminated (Ginsberg et al. 2004). Risk assessment of the fetal period typically relies on maternal dose. However, biomonitoring of cord blood relative to maternal blood may be important to document whether there are substantial maternal-fetal differences in exposure. Evidence on methylmercury suggests that it concentrates in the fetus (Stern and Smith 2003), whereas an evaluation of 29 pesticides suggests similar concentrations across the maternal-fetal unit (Whyatt et al. 2003). 

Chlorpyrifos provides an example of the utility of human pharmacokinetic models to estimate daily dose from biomonitoring data for a rapidly cleared pesticide. The urinary metabolite trichloro-2-pyridinol (TCP) is used in the NHANES study to monitor population exposure to chlorpyrifos (CDC 2005). Several epidemiologic studies have linked chlorpyrifos exposure to adverse birth outcomes through associations between urinary and blood biomarkers and have demonstrated maternal exposure and physiologic measurements in the neonate (Berkowitz et al. 2003, 2004 Whyatt et al. 2004 Needham 2005). 

Needham, L.L. 2005. Assessing exposure to organophosphorus pesticides by biomonitoring in epidemiologic studies of birth outcomes. Environ. Health Perspect. 113(4) 494-498. NRC (National Research Council). 2000. Toxicological Effects of Methylmercury. Washington, DC National Academy Press. 

Contradictory results for associations between pesticide levels indoors (air, dust) and results form human biomonitoring may be due to different volatilities of the pesticides and may be determined by the magnitude in contamination levels. For semivolatile pesticides it may be easier to detect an association, as indoor air and house dust may serve for exposure in contrast to particle-bound pesticides with house dust as the only exposure path. Furthermore high contamination levels make it easier to detect an association, as with low indoor contamination levels associations may be hidden by the ubiquitous presence of pesticides in indoor environments and by nonindoor exposure pathways like dietary intake. 

Acquavella, J. F., Alexander, B. FI., Mandel, J. S., Burns, C. J., and Gustin, C. (2006). Exposure misclas-sification in studies of agricultural pesticides Insights from biomonitoring. Epidemiology 17, 69-74. 

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