Evaluation of potential transmission of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin‐contaminated incinerator emissions to humans via foods

Abstract

Interest in the potential sources of human exposure to TCDD (dioxins, TCDD and equivalents, or 2,3,7,8-tetrachlorodibenzo-p-dioxin) via foods has recently shifted from phenoxy herbicides to products of combustion and waste disposal. Proposals to locate municipal waste combustors in rural areas have raised concerns that emissions, which could contain TCDD, could contaminate animal feeds and such human foods as milk, meat, and vegetables. Important factors that can affect the results of an assessment of incinerator emissions include (1) the emission and deposition rates of TCDD from the source, (2) the fractional retention and half-life of fly ash on plants, (3) the environmental half-life of TCDD, (4) the animal feeding and management systems, (5) the bioavailability of TCDD and related compounds, (6) the metabolism and pharmacokinetics of TCDD in farm animals, (7) food consumption levels, (8) the half-life of TCDD in humans, and (9) the model selected to estimate cancer risk. For persons living in the area of highest deposition near an incinerator, a possible uptake of TCDD from foods of animal origin was estimated to be about 10-40 fg/kg.d, which was much greater than the 1-5 fg/kg.d uptake estimated for foods of plant origin. The total uptake of TCDD from foods by the maximally exposed population will usually be about 500- to 1000-fold greater than that due to inhalation. Although milk was assumed to be the most important food pathway in several previous assessments that evaluated the hazards of airborne emissions, we determined that the deposition-forage-cattle-beef pathway was the more important route of exposure. The previous assessments appear to have used inappropriate pharmacokinetic models for TCDD and to have overestimated pasture use for dairy cows. The amount of TCDD accumulated in soil from airborne emissions was found to be less important than the amount deposited in forage, a finding that is the opposite of the usual conclusions drawn for other routes of TCDD introduction into agricultural environments. Based on the assumption and parameters used in this assessment, the potential human health risks due to TCDD emissions from incinerators are insignificant compared to other background sources of TCDD. It would be desirable to measure TCDD in soil and crops around existing facilities to better evaluate this assessment, but it is likely that concentrations would be too low to reliably quantitate.

Le transfert des micropolluants organiques dans la chaîne alimentaire Etat et perspectives de recherche

“…Les PCDD/F sont issus de combustions incomplètes de matière organique à haute température en présence de chlore [1,20,21], comme l'incinération d'ordures ménagères ou de déchets variés (hospitalier, chimique ou boues d'épuration), dans la métallurgie (cuivre et acier), par les automobiles, dans l'industrie du papier, mais aussi lors de la combustion du charbon ou du bois. Une voie importante est la combustion des PCB qui sont des précurseurs de dioxines.…”

“…Les épandages de boues ne sont pas la source majeure de micropolluants organiques dans les sols, puisque les sols subissent des dépôts atmosphériques. En effet, les composés organiques (dioxines, PCB, HAP) peuvent migrer par voie aérienne lors de procédés d'incinération et faire leur entrée dans les agrosystèmes par dépôt sec et humide [14][15][16][17][18][19][20][21][22][23][24]. Le sol est considéré comme le réservoir majeur en milieu terrestre tout comme les sédiments en milieu aquatique [25].…”

“…Pour l'homme, il est admis que l'exposition moyenne aux dioxines des populations se fait à 90 % par la voie alimentaire [1,[20][21][22][23][24][25][26][27][28][29][30][31][32][33], en particulier par ingestion de graisses animales (lait, produits laitiers, viande, poisson, etc.). Des teneurs moyennes de 30 pg TEQ/g MG ont été observées chez des femmes allaitantes aux Pays-Bas.…”

The Evaluation of Stack Metal Emissions from Hazardous Waste Incinerators: Assessing Human Exposure through Noninhalation Pathways

“…In addition to exposure to airborne toxicants, a multimedia assessment of risk can include an evaluation of human exposure to toxicants that could migrate into surface and groundwater, shallow soils, crops, livestock, and aquatic species. Numerous methods are employed to estimate human exposure to toxicants in different media (5)(6)(7)(8)(9). These methods rely on models that predict the movement of toxicants in the environment.…”

Influence of Short-Term Dietary Measures on Dioxin Concentrations in Human Milk

“…Accumulation in animals takes place readily, whereas uptake in plants is low (4). For humans the main source of dioxins is animal fat, especially meat, dairy products, and fish (5)(6)(7)(8)(9).…”