10 Agricultural Applicators Exposure to 2,4-Dichlorophenoxyacetic Acid R. G. NASH and P. C. KEARNEY—USDA, Pesticide Degradation Laboratory, Beltsville, MD 20705
Downloaded by UNIV LAVAL on July 11, 2016 | http://pubs.acs.org Publication Date: February 26, 1982 | doi: 10.1021/bk-1982-0182.ch010
J. C. MAITLEN and C. R. SELL—USDA, Yakima Agricultural Research Laboratory, Yakima, WA 98902 S. N. FERTIG—USDA, Pesticide Impact Assessment Staff, Agricultural Research Service, Beltsville, MD 20705
Abstract Exposure of workers (applicators and mixer-loaders) to 2,4-D [(2,4-dichlorophenoxy)acetic acid], when applied to wheat under normal use, was determined by measuring urinary excretion of 2,4-D. The participants included 26 ground applicators in North Dakota after a single exposure and 17 aerial applicators in Washington during intermittent exposure. The objective was to ascertain worker exposure base-levels of 2,4-D under normal use conditions. Mean daily urinary excretion of 2,4-D by workers involved in aerial applications was 0.006 mg/kg body weight for pilots and 0.02 mg/kg for mixer/loaders from intermittent exposure. Workers involved in ground applications had maximum mean one-day 2,4-D urinary excretion of 0.002, 0.003, and 0.004 mg/kg, respectively, for applicators, mixer/loaders, and mixer/loader/applicators from a one-time exposure. The E (half-elimination time for total 2,4-D amount excreted) values ranged from 35 to 48 h for the one-time exposed workers making ground applications. A correlation existed between 2,4-D excreted in the urine vs. worker duty for personnel involved in both the aerial and ground applications and 2,4-D excreted in urine from workers of ground application only vs. hours of exposure and vs. amount of 2,4-D applied. There was no apparent correlation between age (except where worker duty and age were correlted) weight, clothing, or 2,4-D formulation. 1/2
Exposure data are important i n any assessment of p e s t i c i d e s a f e t y . 2,4-D i s a widely used h e r b i c i d e so that o p p o r t u n i t i e s e x i s t f o r obtaining r e l i a b l e q u a n t i t a t i v e data on exposure l e v e l s i n s e v e r a l occupational s i t u a t i o n s . One method of measuring human exposure i s by measurement o f 2,4-D l e v e l s i n u r i n e , because most 2,4-D absorbed i s excreted i n the u r i n e and because dermal exposure i s considered the most l i k e l y exposure route (J_,2^3). Exc r e t i o n studies on phenoxy h e r b i c i d e s i n man (3-6) show that 90% of the 2,4,5-T and 75% t o 95% of the 2,4-D was excreted unchanged This chapter not subject to U.S. copyright. Published 1982 American Chemical Society
Plimmer; Pesticide Residues and Exposure ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
PESTICIDE RESIDUES AND
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or as a conjugate within 96 to 144 hours, when each was admini stered o r a l l y at 5 mg per kg body weight. In r a t s and dogs, 2,4,5-T administered by i n t u b a t i o n r e s u l t e d i n r a p i d unchanged 2,4,5-T u r i n a r y e x c r e t i o n by r a t s , but much slower e x c r e t i o n i n dogs with some metabolism occurring. E x c r e t i o n occurred by f i r s t order processes with h a l f e l i m i n a t i o n values (E^/2) f ° > rats, and dogs of 23, 14, and 87 h, r e s p e c t i v e l y . In man, Sauerhoff et a l . (2) found Ε / values of 18 h for 2,4-D. K o h l i et al.(5,6) and Sauerhoff _et aJL. (2) found "&\/2 plasma values of 33, 19 and 12 h f o r 2,4-D, 2,4,5-T, 2,4-D r e s p e c t i v e l y . Sauerhoff et a l . (7) observed that u r i n a r y e x c r e t i o n was even more r a p i d (Εχ/2 ~" H h) when 2,4,5-T was administered intravenously to r a t s . D i s t r i b u t i o n and e l i m i n a t i o n of 2,4,5-T was markedly a l t e r e d when larger doses were administered. Exposure studies by Lavy j2t a l . (_1) on f o r e s t a p p l i c a t o r s showed a 6-day mean e x c r e t i o n of 0.033 mg/kg body weight from s i n g l e day exposures. A considerable range of 2,4,5-T was measur ed i n the urine f o r d i f f e r e n t crew members, with a mixer excreting the highest l e v e l (0.096 mg/kg) and a flagman the lowest l e v e l (0.001 mg/kg) per exposure. In a subsequent 2,4-D study on f o r e s t r y workers, T. L. Lavy, J . D. Walstad, R. R. Flynn, and J . D. Mattice (1980, unpub), found mean values of l e s s than
