Terrestrial wildlife risk assessment for TCDD in land‐applied pulp and paper mill sludge

Abstract

Abstract-A risk assessment was performed to evaluate the potential effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in land-applied pulp and paper mill sludge on terrestrial wildlife. Three representative bird and mammal species were assessed for potential individual risk of adverse effects. A dietary model was used to estimate TCDD exposures of adult birds and mammals, and a pharmacokinetic model was used to estimate exposure for avian embryos. Using the quotient method, modeled exposure levels were compared to published no-observed-adverse-effect levels (NOAELs) for birds and mammals to calculate risk. Monte Carlo analysis was used to consider the variability and uncertainty in the risk estimates. The results suggest that TCDD in landapplied pulp and paper sludge may pose significant individual risks to terrestrial wildlife under certain circumstances. Shrews were found to be most at risk due to their high consumption rate of food items that are expected to bioconcentrate the TCDD from soil at the application sites. Of all possible pathways, only dietary exposure was considered in this investigation. The analysis centered on parameter uncertainty and does not include an assessment of alternative models, although this could be a significant source of uncertainty.

TCDD in land‐applied pulp and paper mill sludge: A valid risk assessment?

“…A manuscript published in Environmental Toxicology and Chemistry (ET&C) by Meyn et al [1] might lead a reader to conclude, inappropriately, that the land application of any sludge derived from bleached chemical pulp mills is hazardous to wildlife. Several areas of concern need to be addressed to enable readers to reach a more informed conclusion.…”

“…. that may lead to lower TCDD [tetrachlorodibenzo-p-dioxide] concentrations,'' [1] they chose not to use newer data on sludge concentrations, which have been submitted to the EPA annually since 1991. These data are widely distributed within the EPA, particularly to the Dioxin Reassessment Group and others in the Office of Research and Development.…”

“…As stated in the introduction to our paper, our intent was to perform a generic analysis ''to establish and implement a methodology to evaluate risks to any given current or future land application site'' [1]. Thus, the results from the paper are not specific to any site.…”

Ecological risk assessment

“…There were several applications of the risk-assessment framework at terrestrial sites. One study by Meyn et al (1997) is a case study for the U.S. EPA framework that addressed terrestrial wildlife risk from 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in land applied pulp and paper mill sludge. This study used a Monte Carlo analysis to provide estimates of the probability of significant risks to each of the representative species.…”

Modeling Cadmium Dynamics in the Guts and Tissues of Small Mammals: Dose Implications for Predators

“…Exposure can occur through various routes, but consumption of contaminated prey items is thought to be the main route of exposure for terrestrial predators [1]. A number of algorithms exist to estimate daily oral intake of contaminants by birds of prey and mammalian predators [2][3][4][5][6][7]. These algorithms use a range of information on dietary preferences, ingestion rates, physiological parameters, allometric relationships, and toxicological data to estimate dose rates to predators.…”