Revisiting Bioaccumulation Criteria for POPs and PBT Assessments

Abstract

Scientists from academia, industry, and government reviewed current international regulations for the screening of commercial chemicals for bioaccumulation in the context of the current state of bioaccumulation science. On the basis of this review, several recommendations were proposed, including a scientific definition for "bioaccumulative substances," improved criteria for the characterization of bioaccumulative substances (including the trophic magnification factor and the biomagnification factor), novel methods for measuring and calculating bioaccumulation properties, and a framework for screening commercial chemicals for bioaccumulative substances. The proposed framework for bioaccumulation screening improves current practices by reducing miscategorization, making more effective use of available bioaccumulation data that currently cannot be considered, reducing the need for animal testing, providing simpler and cheaper test protocols for animal studies in case animal studies are necessary, making use of alternative testing strategies, including in vitro and in silico metabolic transformation assays, and providing a scientific foundation for bioaccumulation screening that can act to harmonize bioaccumulation screening among various jurisdictions.

Summary Review of the Aquatic Toxicology of Munitions Constituents

“…Bioaccumulative chemicals are typically retained in the organism for a long period after the external concentration has declined. A chemical is considered ''bioaccumulative'' in the regulatory context of the Stockholm Convention mostly based on its potential to bioconcentrate (i.e., when its bioaccumulation factor in aquatic species is greater than 5000 ml g -1 wet weight or --in the absence of such data --when the log K OW is greater than 5) (Gobas et al 2009). An overview of regulatory bioaccumulation assessment endpoints and criteria is provided in Gobas et al 2009.…”

“…A chemical is considered ''bioaccumulative'' in the regulatory context of the Stockholm Convention mostly based on its potential to bioconcentrate (i.e., when its bioaccumulation factor in aquatic species is greater than 5000 ml g -1 wet weight or --in the absence of such data --when the log K OW is greater than 5) (Gobas et al 2009). An overview of regulatory bioaccumulation assessment endpoints and criteria is provided in Gobas et al 2009. Explosive MC compounds are not considered bioaccumulative compounds as their BCF values are < 14 ml g -1 , therefore over two orders of magnitude lower than 5000 ml g -1 .…”

Ecological Risk Assessment for Chlorpyrifos in Terrestrial and Aquatic Systems in the United States

“…Integration of the processes of ADME in organisms at quasi-equilibrium is described by several factors, which are ratios between abiotic and biotic compartments. These include bioconcentration factors (BCF), bioaccumulation factors (BAFs), biota/sediment accumulation factors (BSAFs) and, in the case of movement in the food web, biomagnification (BMFs) or trophic magnification factors (TMFs) (Gobas et al 2009). …”

Mathematical relationships between metrics of chemical bioaccumulation in fish

“…Biomagnification factors are influenced by the approach to steady state, by growth dilution, and by biotransformation rates in both prey and predator, making simple interpretation difficult. The review by Gobas et al [9] favored the use of BMF for characterizing the bioaccumulative nature of substances because biomagnifying substances differ fundamentally from non-biomagnifying substances in that their fugacity and chemical potential increase from prey to predator in a functioning ecosystem. Non-biomagnifying chemicals cannot achieve such an increase.…”

“…As part of this initiative, various kinds of bioaccumulation data and metrics are used to determine whether and to what extent chemicals are bioaccumulative. Extensive literature exists on bioaccumulation from scientific and regulatory perspectives, examples being the reviews by Barber [3,4], Mackay and Fraser [5], Arnot and Gobas [6], Ehrlich et al [7], Burkhard et al [8], and Gobas et al [9], the latter summarizing the conclusions of a SETAC-sponsored workshop held in 2008. These and other reviews have pointed out the existence of several metrics of bioaccumulation that differ in definition, in regulatory application, and in adoption by the scientific community.…”