US EPA

1032211 

Journal Article 

Review 

Source and occurrence of environmental contaminants 

Somers, E; Smith, DM 

1971 

1 

Food and Cosmetics Toxicology
ISSN: 0015-6264
EISSN: 1878-6049 

9 

2 

185-193 

English 

4934608 

10.1016/0015-6264(71)90304-x 

WOS:A1971J632500003 

The sources and occurrences of pesticides, polychlorinated biphenyls (PCBs) and chlorodioxins as environmental contaminants are discussed. Particular attention is given to the occurrence of residues in Food in Canada. Of the 400 pesticides registered by the Canadian Department of Agriculture, 97 are permitted as residues in food crops. During 1969, the Food and Drug Directorate examined about 3600 foods for pesticide residues. About 70% of the samples analyzed contained detectable pesticide residues, most of which were DDT and its analogs. Of the products from domestic trade, 5% contained residues about the permitted levels. D. C. Smith (1971) found that the average daily intake of organochlorine pesticides/person in 1969 was 24 mcg. Surveys of the Canadian population (Read and McKinley, 1961; Brown, 1969) revealed 4 to 5 ppm of DDT compounds in human adipose tissue. In a survey of autopsy tissue from 221 accident victims, 4 to 5 ppm of DDT compounds and traces of heptachlor epoxide were found (Ritcey et al., 1971 in press). These investigators found an average of 0.14 ppm DDT compounds (70% as p,p'-DDE) and traces of dieldrin and heptachlor epoxide in 132 human milk samples. PCBs have been found in a range of organisms, in foods and in human fat and milk in many industrialized countries. The PCB residue pattern that is now emerging is similar to that for the organochlorine insecticides. The chlorophenols, widely used as wood preservatives, fungicides, disinfectants and contact herbicides, form chlorinated derivatives of dibenzo-p-dioxin by being heated. Dioxins can occur as impurities in pesticides. Higginbotham et al. (1968) suggested that commercial chlorophenols could be precursors of the chick edema factor. Much more information is needed about the chemical stability and metabolism of the dioxins. Inadequate methodology prevents the analysis of foods for these compounds at the present time. The presence of trace metals (lead, cadmium, mercury and arsenic) in food is also discussed. It is suggested that an audit of environmental contaminants is urgently needed before meaningful controls can be devised. 1971