GPI Toxics Campaign - Human Health Effects

D I O X I N A N D H E A L T H

Levels of Human Exposure

A picogram is a trillionth of a gram.
One picogram of the most potent dioxin, TCDD, contains 1.88 billion molecules of dioxin, each of which is theoretically capable of disrupting a cell.

In general, levels of PCDD/Fs in blood, adipose tissue and milk are higher in industrialised nations than in developing nations. It has been found dioxins can persist in human tissues for decades. For example, individuals exposed occupationally to high levels of dioxins had elevated levels of these compounds in their tissues up to 34 years after exposure.

Estimates are often based on intake of dioxins and do not include dioxin-like PCBs or other dioxin-like compounds. Inclusion of dioxin-like PCBs could raise these estimates by 35-50%.

Exposure levels to 2,3,7,8-TCDD in industrialized nations are estimated to be about 20 to 40 pg/day (.3-.6 pg TCDD/kg/day). Levels of dioxin-like compounds found in human tissue/blood appear similar in Europe and North America.

Highly Exposed Populations

Consumption of breast milk by nursing infants may lead to higher levels of exposure during the early postnatal period as compared to intake in the diet later in life. One study of 42 U.S. women found an average of 16 pg TEQ/g (16 ppt), 3.3 ppt of which was 2,3,7,8-TCDD, in the lipid portion of breast milk. A much larger study in Germany found an average of 29 pg TEQ/g (29 ppt) in the lipid portion of breast milk. These estimates do not include a contribution to total TEQ from dioxin- like PCBs.

Workers in industries where dioxins are a by-product as well as the communities around these industrial sources of dioxin will have higher exposure to dioxins, as will people such as the Inuit in colder regions of the earth like the Arctic, where dioxin like compounds from distant sources accumulate in the food chain.

No Safe Dose

"...adverse effects may be occurring at levels lower than originally thought to represent no observed adverse effect levels."

US EPA Draft Chapter on Dioxin Risk Characterization, Dated May 2, 1994

Several lines of scientific evidence indicates that global dioxin pollution has already reached a level that threatens human health:

First, there appears to be no safe dose of dioxin -- no threshold below which effects do not occur. Thus, even the low doses to which the general population is subject may cause subtle impacts on human health.

o Second, in their review of dioxin, the US Environmental Protection Agency noted that "the weight of evidence suggests concern for the impact of these chemicals on humans at or near current background levels." Another study noted that: '.. the available data indicate that high-level human exposure to dioxins produce adverse health effects and that humans are a sensitive species to the toxic effects of dioxins. Whether these low-dose effects are occurring in the general population or the more highly exposed subpopulations remains to be determined." (DeVito et.al. 1995)

Finally, there is no doubt that the quantity of dioxins now in the environment has caused severe health damage to wildlife -- particularly species high on the food chain,such as bald eagles, marine mammals, and other species in the Great Lakes, Baltic Sea, and elsewhere. If dioxin levels are high enough to cause these effects in wildlife, humans, who are high on the food chain but have slower generation times, are also at risk.

Thus, global dioxin contamination poses a long-term, large-scale hazard to the health of humans and other species. Indeed, the effects may be occurring already: there is evidence that sperm counts have declined substantially in many countries in the last 50 years and rates of most types of cancer and endometriosis have also increased steadily. Exposure to environmental pollutants, including dioxin, is a possible cause of this trend. Global dioxin pollution threatens the viability and quality of life of future generations. It is clearly time for action to stop all further releases of dioxin into the environment.