Worker pesticide exposure studies

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. 

Worker pesticide exposure which is primarily dermal can be acquired either as a result of accidental spillage or as a result of saturation of the clothing and penetration of the chemical through the fabric. Both laboratory and field data from these studies suggested that significant worker protection against... 

Study of field worker pesticide exposure data has shown that several factors influence exposure. These factors are mostly physical in nature. Most of the time the chemical properties of the pesticide do not come into play as determinants that may have an impact on exposure levels. The physical factors are ... 

The test substance may be acquired in a number of ways. One common method is to purchase the product from a chemical dealer. This method of acquiring the test substance for a worker exposure or re-entry study allows one to proceed rapidly with the execution of the field portion of the study without the serious delays encountered while waiting for a test substance to be manufactured, assayed, and shipped to the site. Although having a test substance formulation which has been assayed under GLP standards and for which a certificate of analysis has been shipped to the test site is desirable, there are several instances when this is not practical. For example, one may encounter a worker exposure study where the pesticide to be evaluated is sold only in mini-bulk or even large bulk quantities holding as much as 2000 gal. In this case, duplicate 5-10-g or 5-10-mL retainer samples should be taken from the bulk or mini-bulk tanks for assay after the worker exposure study is in progress. 

The test substance should be stored in a locked facility at or near the test site. Most pesticide products are manufactured to withstand extreme temperatures, therefore most test substances used for re-entry and worker exposure studies may be stored under ambient conditions. One should read the label of the product carefully to discern if there are any extraordinary storage conditions required for the pesticide product. Temperatures at the test substance storage location should be monitored daily using a max/min thermometer or similar device that can record daily fluctuations of temperatures. 

The measurement of foot exposure to pesticides is not commonly performed in worker exposure studies. However, the measurement of foot exposure can be accomplished by either using socks as a foot dosimeter or by washing the foot using similar procedures to those used for the face wipe. 

Due to the low volatility of cyromazine and the use of water-soluble bags for packaging the Trigard formulation, the main routes of exposure were expected to be from direct contact with the product or spray mixture on contaminated surfaces. Previous experience with pesticides worker exposure studies indicated that exposure from vapors or spray mist would be a minor factor. This can easily be confirmed by the PHED or similar published sources however, the extent of exposure from inhaling the product as dust is less well known. This route of exposure was also assumed to be minor, particularly with the use of water-soluble bag packaging. Given the low mammalian toxicity of cyromazine, the operators did not wear respiratory protection. 

From the late 1960s until the early 1980s, a large number of worker exposure studies were reported which used the methods of passive dosimetry — that is, methods that measured potential contact with pesticides but did not measure the actual amount of pesticide absorbed by the workers bodies. These studies were extensively reviewed by Wolfe (1976) and later by Davis (1980). 

Cohort studies of agricultural chemical production workers found decreased mortality from all cancers among workers who had probable exposure to atrazine. Findings of an increased risk of non-Hodgkin lymphoma among farmers could not be attributed to atrazine exposure when adjustment was made for other pesticide exposure. ... 

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. 

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). 

ELISA could potentially be used advantageously in many types of exposure and monitoring situations, for paraquat and other pesticides amenable to ELISA analysis. An obvious use of ELISA is the detection of pesticide residue levels in plant and animal tissues, or food extracts. Biological specimens such as plasma and urine currently analyzed by RIA seem particularly amenable to analysis by ELISA. Portable field kits could be developed to determine safe worker re-entry times into treated fields. Environmental samples such as soil, water, and air, can be analyzed by the ELISA. Pesticide conjugates have been proposed for skin testing of individuals suspected of sensitivity to pesticides (fi.) the ELISA could be used to detect specific antibodies in these individuals and aid in exposure studies. 

INTRODUCTION 14 PESTICIDE CATEGORIES 15 PESTICIDE HANDLERS 15 Agricultural Pesticide Handlers 15 Tasks Performed by an Individual 16 Factors Affecting Exposure 16 Residential and Institutional Pesticide Handlers 18 Families of Pesticide Handlers 19 STUDY DESIGN CONSIDERATIONS 20 Worker Stratification 21 Routes of Exposure 21 Respiratory Exposure 21 Dermal Exposure 21 Sampling Strategy Selection 21 Statistical Analysis 22 PROTECTION OF HUMAN SUBJECTS 22 PESTICIDE EXPOSURE MONITORING METHODS 23 Passive Dosimetry 23... 

In the past decade, however, the occupational health and safety community has directed greater attention to pesticide exposures among workers and then-families. Initiatives, focused on minority workers, women and the children of workers, have also made pesticide exposure assessment a timely topic for scientific invesfigation and medical management. Finally, major new epidemiologic initiatives in both the United States and Canada have given new stimuli to the study of occupational pesticide exposme in farming (Alavanja et al, 1996 Arbuckle et al., 1999). 

Kross, B.C., H.F. Nicholson and L.K. Ogilvie (1996). Methods Development Study for Measuring Pesticide Exposure to Golf Course Workers using Video Imaging Techniques, Appl. Occup. Environ. Hyg., 11, 1346-1350. 

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