Pesticides applicators, dermal exposure

Dermal exposure to methyl parathion is not likely to be a health concern to the general population, with the possible exception of individuals in the immediate vicinity of a field during application of the pesticide. Dermal exposure, however, is a major source of exposure for workers directly involved in the manufacture, application, and cleanup of the chemical, and for field workers. Laundry workers cleaning the clothing of such workers may also be exposed. 

The most important routes of exposure to endosulfan for the general population are ingestion of food and the use of tobacco products with endosulfan residues remaining after treatment. Farmers, pesticide applicators, and individuals living in the vicinity of hazardous waste disposal sites contaminated with endosulfan may receive additional exposure through dermal contact and inhalation. 

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. 

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. 

D.R. Hackathorn and D.C. Eberhart, Database proposal for use in predicting mixer-loader/applicator exposure, in Dermal Exposure Related to Pesticide Use Discussion of Risk Assessment, ed. R.C. Honeycutt, G. Zweig, and N.N. Ragsdale, ACS Symposium Series 273, American Chemical Society, Washington, DC, pp. 341-355 (1985). 

Chester, G., Loftus, N.J., Woollen, B.H., and Anema, B.P. (1990b) The effectiveness of protective clothing in reducing dermal exposure to, and absorption of, the herbicide fluazifop-P-butyl by mixer-loader-applicators using tractor sprayers, in Book of Abstracts, Seventh International Congress of Pesticide Chemistry, Vol. Ill, Freshe, H. and Kesseler-Smith, E., Eds., Conway, Hamburg. 

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

The first pesticide exposure study was reported by Griffiths et al. (1951). Parathion was trapped on respirator filter discs during application to citrus trees. Batchelor and Walker (1954) expanded exposure monitoring to include the estimation of potential dermal exposure using pads attached to workers clothing. Durham and Wolfe (1962), in their classic review of worker exposure methodologies, also provided some experimental validation for the best available methods. 

There are few studies that specifically describe the effects of heptachlor or heptachlor epoxide in humans following exposure via the oral, inhalation, or dermal routes. There are data on the health effects of chlordane from occupational studies of pesticide applicators and manufacturers, and from studies of people who consumed food contaminated with chlordane and heptachlor. Chlordane is a pesticide that is structurally similar to heptachlor, and technical-grade preparations may contain... 

Most of the data located concerning the health effects of heptachlor and heptachlor epoxide in humans come from case reports and occupational epidemiology studies of workers engaged either in the manufacture or application of pesticides. There is some information on people who have consumed heptachlor-contaminated food or dairy products, but no adverse health effects have been related to these exposures. The occupational studies involve exposures that are predominantly inhalation with contributions from dermal exposure, whereas all the animal studies were conducted using oral or intraperitoneal exposures. The occupational and case reports provide no quantitation of dose or duration of exposure, which makes it impossible to determine with any precision the effect levels for humans. There are no data that indicate that heptachlor or heptachlor epoxide are carcinogenic to humans. However, human studies are limited by the long latency period of carcinogenesis and by ascertainment and follow-up biases. 

There are no data on intermediate-duration inhalation or dermal exposures in either humans or animals. Data on intermediate inhalation and dermal exposures would be useful since the inhalation of vapors or direct contact with residual heptachlor from residential pesticide application or at NPL sites may be potential routes of exposure for the general population. 

Pesticide mixers and applicators at Farms A and B, and also at an active farm not having a CCC, were monitored for topical (dermal) exposure throughout the 1980 season. No Increased exposure was measured as a result of using the Chemical Control Centers. A paper addressing potential applicator exposure In this and similar situations Is In preparatlon( ). 

Dermal Exposure Levels. Setting acceptable maximum dermal exposure levels to specific pesticides has been difficult. This is primarily due to a lack of specific data on dermal transport rates for specific pesticides as related to adverse effect levels and presumed no-effect levels. We are now requiring such data from the registrants, and our Department has a suggested protocol (1) that is offered to registrants that will provide such information from animal exposure studies. This dermal transport rate information is important in setting minimum field reentry intervals for field workers as well as in evaluating exposure levels of mixers, loaders, and applicators. 

The use of closed systems has been required in California for transfer of toxicity category one liquid pesticides from the manufacturer s container into the mix tank and then into the application vehicle tank. It appears that this process has considerably reduced both dermal and inhalation exposure. The use of probes that are inserted and then removed from containers reduces dermal exposure up to ten-fold it also appears that the use of built-in probes further reduces exposure to the mixer-loader by up to another ten-fold factor in some cases. 

The routes of exposure to POPs for human beings include inhalation, dermal exposure, and ingestion of water or food contaminated by POPs. Cases of occupational or accidental exposure to POPs have been recorded, particularly during the application of pesticides (Vallack et al., 1998). However, food consumption is one of the most important pathways of exposure for the general population (Dougherty et al., 2000 Stefanelli et al., 2004). 

Occupational pesticide exposure holds a peculiar status within the field of occupational health and safety, both from a scientific and regulatory perspective. Methods for personal monitoring of dermal exposure first arose in the context of pesticide applications in agriculture, pioneered by scientists in the USA Public Health Service (Batchelor and Walker, 1954 Durham and Wolfe, 1962). These methods gained worldwide recognition in the early 1960s, and remain a component of exposure assessment practice today. This work pre-dated most personal monitoring methods that were developed for industrial workplaces. 

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. 

Methner, M.M. and R.A. Fenske (1994a). Pesticide Exposure During Greenhouse Applications, Part I. Dermal Exposure Reduction Due to Directional Ventilation and Worker Training, Appl Occup. Environ. Hyg., 9, 560-566. 

The many uses of an indoor pesticide require fhaf exposure estimates should be based on fhe mosf likely application dial will lead fo fhe highesf probabilify of dermal and inhalation confacf. For insfance, a broadcasf carpel Ireatmenl is generally presumed fo resull in more pesticide surface residue being accessible to individuals fhan fhe amounf or accessibility of residue when the pesticide is placed inside an insect bait station. 

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