ANALYSIS OF PCDD AND PCDF PATTERNS IN SOIL SAMPLES - USE IN THE ESTIMATION OF THE RISK OF EXPOSURE

Public concern about PCDD and PCDF in incinerator emissions has focused attention on the potential for these compounds to enter the food chain. The Ontario Ministry of the Environment has extensively investigated PCDD/PCDF levels in incinerator emissions (4,18,24), urban soils near incinerators (14) and major food products available for consumption in Ontario (3). No clearcut connection between emission sources and levels of PCDD/PCDF in soil or food has been found. However the number of samples analysed in these studies has been limited. Since soil may be a pathway of human exposure through dermal contact or ingestion, a wider data set of PCDD/PCDF analyses of U. S. and Canadian soils from rural, urban and industrial sources was examined. Levels, patterns and quantities of 2,3,7,8-TCDD toxicity equivalents (TEQ) of PCDD/PCDF in soils from various sources were analysed. Using a worst case scenario, an infant consuming urban soil containing the mean plus three standard deviations (77 ppt TEQ) would ingest less than one-tenth the tolerable daily intake. © 1990.