Application exposure herbicides

Libich 5, To JC, Frank R, 5irons GJ. Occupational exposure of herbicide applicators to herbicides used along electric powertrans-mission line right-of-way. Am Ind Hyg Assoc J 1984 45 56-62. 

The First Study. Forest-applicator exposure to MSMA and cacofirst studied by Tarrant and Allard (9). They collected individual urine samples on Monday mornings ari7 Friday afternoons for 9 consecutive weeks from five applicators (each using a different combination of application method and chemical) and one control. Workers were supplied with clean clothes daily, including two pair of cotton gloves (to be changed at noon, or earlier if one pair became substantially contaminated with herbicide). Complete data were obtained for weeks 2, 3, 4, 7, and 8 (except for the injection hatchet-cacodylic acid combination, which was not included in the analysis). 

It Is realized that the pharmacokinetics governing absorption and excretion rates for many pesticides have not been fully evaluated. This fact should not automatically release the researcher conducting applicator exposure measurements from any obligations to attempt to gather Information regarding the absorbed dose. Since analysis of urine sometimes reveals the presence of a degradation product or the parent pesticide itself, as In the case of the phenoxy herbicides, a researcher is remiss If he does not at least attempt to locate a definable urinary component. 

Lavy, T.L. Mattice, J.D. Project Completion Report to United States Department of Agriculture on Exposure of Forestry Applicators Using Herbicide Formulations Containing 2,4-D,... 

PCP is commonly used as a wood preservative having both antifungal and insecticide properties. It has also been used in a range of areas for antifungal, antibacterial, general herbicide, and slime prevention in both industrial and consumer applications. Chronic exposure to PCP has effects on the liver, kidneys, and immune system. PCP also has the potential to cause reproductive problems and has been listed as a probable carcinogen. 

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. 

Cowell J.E., Danhaus, R.G., Kunstman, J.L., Hackett, A.G., Oppenhuizen, M.E., and Steimetz, J.R. (1987) Operator exposure from closed system loading and application of alachlor herbicide, Arch. Environ. Contam. Toxicol., 16 327-332. 

Dubelman, S., Lauer, R., Arras, D.D., and Adams, S.A. (1982) Operator exposure measurements during application of the herbicide diallate, /. Agric. Food. Chem., 30 528-532. 

When these three cancers (soft-tissue sarcoma, non-Hodgkin s leukemia, and Hodgkin s disease) are considered as a whole, it is noteworthy that the strongest evidence for an association with exposure to phenoxy herbicides is the series of case-control studies conducted by Hardell [Lennart Harden, a Swedish physician] and colleagues and the cohort studies of herbicide applicators and agricultural workers.25 26... 

It should be noted that hazard or risk is a function of exposure as well as of toxicity. Thus, an important aspect of this continued debate on 2,1+,5-T is the need for representative data on real exposure in humans, not only for applicators of the herbicide but for the populace at large. EPA s RPAR Position Document 1 (l) included estimates of exposure to 2,1i,5-T based on direct measurements of external contamination by other pesticides applied with equipment similar to that used for 2,li,5-T. However, in most cases, application conditions were quite different from those used for 2,1+,5-T. 

EPA Study. The first published report of studies on 2,it,5-T applicators was by Shafik et al. of EPA in 1971 (] ) They analyzed urine samples collected from people occupationally exposed to 2,lt-D and 2,it,5-T, and reported higher exposure in spray operators than in those who had less direct contact with the herbicides. 

T excreted by the 21 forest workers in two exposures under typical field conditions. The highest dose was received by mixers who handled the herbicide concentrate, followed by applicators using backpack sprayers, spray tractor drivers, helicopter... 

Data from analyses of air samples in Lavy s 2,h,5-T study (15, 19) and 2,L-D study (20) indicate that exposure via inhalation was insignificant during application of low volatile ester formulations of these herbicides. 

Sporadic exposure resulting in doses of less than 0.1 mg/kg of body weight per day spent spraying 2,4,5-T would not appear to pose a significant risk to applicators of the herbicide, even if the 2,4,5-T contains trace amounts of the impurity 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Perspective on the potential risk can be gained by comparison of this estimated maximum dose (0.1 mg/kg) with doses which caused no effect in animals treated daily for extended periods. 

The extent to which exposure to pesticides may be hazardous to applicators depends upon exposure levels and the toxicity of the compounds. The phenoxy herbicides have been used for nearly 40 years, and no injury to workers properly using these herbicides has been clearly established. 

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