Polychlorinated Dibenzodioxins - Sources of Human Intake

Sources of Human Intake

Tolerable daily, monthly or annual intakes have been set by the World Health Organization and a number of governments. Dioxins enter the general population almost exclusively from ingestion of food, specifically through the consumption of fish, meat, and dairy products since dioxins are fat-soluble and readily climb the food chain.

Most controversial is the United States Environmental Protection Agency (US EPA) assessment's (draft) finding that any reference dose that were to be set would be far below current average intakes. This is based on linear extrapolation model of cancer risk, which is not generally accepted for chemicals promoting cancer caused by other factors rather than initiating the cancer by itself.

Children are passed substantial body burdens by their mothers, and breastfeeding increases the child's body burden. Children's daily intakes during breast feeding are often many times above the intakes of adults based on body weight. This is why the WHO consultation group assessed the tolerable intake so as to prevent a woman from accumulating harmful body burdens before her first pregnancy. Breast fed children usually still have higher dioxin body burdens than non breast fed children. The WHO still recommends breast feeding for its other benefits. In many countries dioxins in breast milk have decreased by even 90% during the two last decades.

Dioxins are also in typical cigarette smoke. Dioxin in cigarette smoke was noted as "understudied" by the US EPA in its "Re-Evaluating Dioxin" (1995). In that same document, the US EPA acknowledged that dioxin in cigarettes is "anthropogenic" (man-made, "not likely in nature").