Pesticides applicators, measuring exposure

The purpose of this article is to present a detailed description of the current field methods for collection of samples while measuring exposure of pesticides to farm workers. These current field methods encompass detailed descriptions of the methods for measuring respiratory and also dermal exposure for workers who handle the pesticide products directly (mixer-loaders and applicators) and for re-entry workers who are exposed to pesticide dislodgeable residues when re-entering treated crops. 

Fenske, R.A. (1988) Comparative assessment of protective clothing performance by measurement of dermal exposure during pesticide applications, Appl. Ind. Hygiene, 3 207-213. 

Deaths of target organisms associated with intentional pesticide applications to insect-infested crops, weed-choked roadsides, and nematode-laced fields are predictable, desirable, and relatively easy to measure. Likewise, catastropic releases of chlorine from ruptured tank cars or of crude oil from scuttled supertankers may produce a spectrum of biological effects including toxicity. These events are easily associated with exposures to toxic substances and particular environmental circumstances. 

Exposure was measured for four crews in Arkansas using three methods of pesticide application backpack, tractor-drawn mist blower, and helicopter (two crews). Comparisons of exposure levels were made between crews and within crews in relation to work duties. 

Machado, J., G. Neto, T. Matuo and Y.K. Matuo (1992). Dermal Exposure of Pesticide Applicators in Staked Tomato (Lycopersicon Esculentum Mill) Crops Efficiency of a Safety Measure in the Application Equipment, Bull. Environ. Contam. Toxicol, 48, 529-534. 

Measurement of the post-application residential exposure is, in many ways, more complicated than the agricultural re-entry since there may be multiple sources and routes of exposure, varying amounts of time spent in contact with these sources and a much wider age and health range in the exposed population (USEPA, 1991, 1999a). Chemicals such as pesticides that are released into or otherwise enter the residential enviromnent tend to partition into various compartments, either through direct dispersion in indoor air or through adsorption onto surfaces that serve as sinks from which material can subsequently be released into the air (Ross et al., 1990, 1991). A detailed discussion of the measurement of pesticides in the residential enviromnent is presented in Chapter 3. 

Another method to help quantify pesticide exposures is the use of exposure databases. The exposures measured for pesticide applicator studies are now... 

Petroleum products are an integral part of our modern lives. It is nearly impossible to avoid exposure to hydrocarbons from petroleum products, whether it is from gasoline fumes at the pump, spilled crankcase oil on asphalt, solvents used at home or work, or pesticide applications that use petroleum products as carriers. There are concerns with both short-term (accidents) and long-term exposures to petroleum hydrocarbons (e.g., contaminated drinking water). Gross measures of Total Petroleum Hydrocarbons (TPH) in soil or water are not particularly valuable for assessing either the potential for exposure to TPH or the impacts of such exposure on public health. This chapter addresses questions related to the first point what are the levels of contamination in the environment, what happens to petroleum hydrocarbons in the environment, and what is the likelihood that individuals or populations will be exposed to petroleum hydrocarbons at levels thought to be of concern ... 

Berger-Preiss et al. (2002) measured indoor pyrethroid exposure in 80 homes with woollen textile floor coverings. While permethrin concentrations in house dust were high (mean 53.7 pg g ), the permethrin concentrations in suspended particles were very low (mean 2.8 ng m ). Roinestad et al. (1993) identified 30 pesticides in household dust ranging from 80 (diazinon) to 15000 (chlorpyrifos) ng g . Permethrin levels decreased from 2550-3850 (just after application) to 550-675 ng g 8 weeks after pesticide application. However, dichlorvos and... 

The exposure pad method, combined with measurement of urinary metabolites, has been used to compare worker exposure for different pesticide application methods (33, 34) as well as to monitor formulating plant worker exposure (35) and homeowner exposure (36). 

There are, however, several apparent discrepancies. The first is the ratio calculated from literature values dealing with carbaryl exposure to pesticide applicators and fruit thinners in an apple orchard (4) This ratio (about 0.6x10 cm h ) was considerably lower than the range seen in Table IX. The difference may be due to the fact that Maitlen et al. (4) measured total and not dislodgeable foliar residues, thus leading to lower values than those obtained by us and others. 

Unfortunately the Ideal situation does not exist and there are many difficulties which must be overcome before accurate risk assessments can be conducted. For pesticide applicators, the dermal route has been shown to be the most Important one. However, the methods used to measure the amount of pesticide landing on the skin are not very reliable and many studies conducted In the past did not try to estimate hand exposure. This omission Is a serious one because it has been shown that a very large percentage of the total dermal exposure Is to the hands. New methods using fluorescent tracer techniques are promising and will undoubtedly lead to more quantitative estimates of contact exposure. 

Plant uptake is one of several routes by which an organic contaminant can enter man s food chain. The amount of uptake depends on plant species, concentration, depth of placement, soil type, temperature, moisture, and many other parameters. Translocation of the absorbed material into various plant parts will determine the degree of man s exposure—i.e., whether the material moves to an edible portion of the plant. Past experience with nonpolar chlorinated pesticides suggested optimal uptake conditions are achieved when the chemical is placed in a soil with low adsorptive capacity e.g., a sand), evenly distributed throughout the soil profile, and with oil producing plants. Plant experiments were conducted with one set of parameters that would be optimal for uptake and translocation. The uptake of two dioxins and one phenol (2,4-dichlorophenol (DCP)) from one soil was measured in soybean and oats (7). The application rates were DCP = 0.07 ppm, DCDD 0.10 ppm, and TCDD = 0.06 ppm. The specific activity of the com-... 

Both inner and outer whole-body dosimeters are common tools to measure successfully dermal exposure to pesticide workers and are employed in a variety of ways in mixer-loader/applicator or re-entry studies. 

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