consumption from these areas (Powell 1984). In Massachusetts, 6 ponds were 

 surveyed for 2,3,7,8-TCDD in 1983 after prior treatment with phenoxy 

 herbicides between 1958 and 1978 (Anon. 1984). Only one fish, a brown 

 bullhead ( Ictalurus nebulosus ), age 3+ years, contained measurable (25 ppt) 

 dioxin levels. Residues were not detectable in other species of fish sampled, 

 including several species of ictalurid catfish, yellow perch ( Perca 

 flavescens ), and chain pickerel ( Esox niger ). Negative results (less than 10 

 ppt 2,3,7,8-TCDD) were also documented in freshwater fish from Arkansas and 

 Texas following spraying of the herbicide 2,4,5-T (Shadoff et al. 1977). 



In birds, the levels of 2,3,7,8-TCDD have been decreasing, according to 

 analysis of herring gull eggs from Lake Ontario. During the decade 1970-1980, 

 there was a reduction of about 50% in 2,3,7,8-TCDD levels every two years 

 (Ogilvie 1981; NRCC 1981; Nriagu and Simmons 1984). The reasons for the 

 decline are unknown, and the relevance to higher-chlorinated PCDDs has not yet 

 been determined. Until these questions are resolved and more substantative 

 data are acquired on dioxin residues in birds, the current predictive trends 

 on decline rates should be interpreted with caution. 



Much of the information on 2,3,7,8-TCDD levels in wildlife and domestic 

 livestock are from the vicinity of Seveso, Italy (Table 3). There, on July 

 10, 1976, a chemical cloud containing 2,3,7,8-TCDD was released as a result of 

 an industrial accident. It contaminated the food (hay, grass, cut-up corn) of 

 dairy cows (Fanelli et al . 1980a). Grossly elevated levels (7,900 ppt) were 

 measured in milk from these herds at concentrations considered hazardous to 

 human health, i.e., more than 7,000 ppt (Fanelli et al. 1980a). Wildlife from 

 the most heavily-contaminated area appeared to accumulate 2,3,7,8-TCOD. Field 

 mice ( Microtus arvalis ), for example, contained very high whole body 

 concentrations of 2,3,7,8-TCDD (up to 49,000 ppt) almost 2 years after the 

 critical contamination. The mechanisms for this phenomenon included ingestion 

 of contaminated soil and licking of their dioxin-contaminated pelt (Fanelli et 

 al. 1980c). In another study, no 2,3,7,8-TCDD was detected in livers of 

 mountain beavers ( Aplodontia rufa ) that fed for 45 to 60 days in Oregon 

 forests that had been sprayed with 2.2 kg of 2,4,5-T/ha (Newton and Snyder 

 1978). Although it was presumed that the herbicide was heavily contaminated 

 with dioxins, no chemical analysis of the 2,4,5-T was performed. 



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