Anne V. Weisbrod

Workgroup report: review of fish bioaccumulation databases used to identify persistent, bioaccumulative, toxic substances.

Chemical management programs strive to protect human health and the environment by accurately identifying persistent, bioaccumulative, toxic substances and restricting their use in commerce. The advance of these programs is challenged by the reality that few empirical data are available for the tens of thousands of commercial substances that require evaluation. Therefore, most preliminary assessments rely on model predictions and data extrapolation. In November 2005, a workshop was held for experts from governments, industry, and academia to examine the availability and quality of in vivo fish bioconcentration and bioaccumulation data, and to propose steps to improve its prediction. The workshop focused on fish data because regulatory assessments predominantly focus on the bioconcentration of substances from water into fish, as measured using in vivo tests or predicted using computer models. In this article we review of the quantity, features, and public availability of bioconcentration, bioaccumulation, and biota–sediment accumulation data. The workshop revealed that there is significant overlap in the data contained within the various fish bioaccumulation data sources reviewed, and further, that no database contained all of the available fish bioaccumulation data. We believe that a majority of the available bioaccumulation data have been used in the development and testing of quantitative structure–activity relationships and computer models currently in use. Workshop recommendations included the publication of guidance on bioconcentration study quality, the combination of data from various sources to permit better access for modelers and assessors, and the review of chemical domains of existing models to identify areas for expansion.

The state of in vitro science for use in bioaccumulation assessments for fish

Through the concerted evaluations of thousands of commercial substances for the qualities of persistence, bioaccumulation, and toxicity as a result of the United Nations Environment Programs Stockholm Convention, it has become apparent that fewer empirical data are available on bioaccumulation than other endpoints and that bioaccumulation models were not designed to accommodate all chemical classes. Due to the number of chemicals that may require further assessment, in vivo testing is cost prohibitive and discouraged due to the large number of animals needed. Although in vitro systems are less developed and characterized for fish, multiple high-throughput in vitro assays have been used to explore the dietary uptake and elimination of pharmaceuticals and other xenobiotics by mammals. While similar processes determine bioaccumulation in mammalian species, a review of methods to measure chemical bioavailability in fish screening systems, such as chemical biotransformation or metabolism in tissue slices, perfused tissues, fish embryos, primary and immortalized cell lines, and subcellular fractions, suggest quantitative and qualitative differences between fish and mammals exist. Using in vitro data in assessments for whole organisms or populations requires certain considerations and assumptions to scale data from a test tube to a fish, and across fish species. Also, different models may incorporate the predominant site of metabolism, such as the liver, and significant presystemic metabolism by the gill or gastrointestinal system to help accurately convert in vitro data into representative whole-animal metabolism and subsequent bioaccumulation potential. The development of animal alternative tests for fish bioaccumulation assessment is framed in the context of in vitro data requirements for regulatory assessments in Europe and Canada.

Guidance for Evaluating In Vivo Fish Bioaccumulation Data

ABSTRACT Currently, the laboratory-derived fish bioconcentration factor (BCF) serves as one of the primary data sources used to assess the potential for a chemical to bioaccumulate. Consequently, fish BCF values serve a central role in decision making and provide the basis for development of quantitative structure–property relationships (QSPRs) used to predict the bioaccumulation potential of untested compounds. However, practical guidance for critically reviewing experimental BCF studies is limited. This lack of transparent guidance hinders improvement in predictive models and can lead to uninformed chemical management decisions. To address this concern, a multiple-stakeholder workshop of experts from government, industry, and academia was convened by the International Life Sciences Institute Health and Environmental Sciences Institute to examine the data availability and quality issues associated with in vivo fish bioconcentration and bioaccumulation data. This paper provides guidance for evaluating key aspects of study design and conduct that must be considered when judging the reliability and adequacy of reported laboratory bioaccumulation data. Key criteria identified for judging study reliability include 1) clear specification of test substance and fish species investigated, 2) analysis of test substance in both fish tissue and exposure medium, 3) no significant adverse effects on exposed test fish, and 4) a reported test BCF that reflects steady-state conditions with unambiguous units. This guidance is then applied to 2 data-rich chemicals (anthracene and 2,3,7,8-tetrachlorodibenzo-p-dioxin) to illustrate the critical need for applying a systematic data quality assessment process. Use of these guidelines will foster development of more accurate QSPR models, improve the performance and reporting of future laboratory studies, and strengthen the technical basis for bioaccumulation assessment in chemicals management.

Use of In Vitro Absorption, Distribution, Metabolism, and Excretion (ADME) Data in Bioaccumulation Assessments for Fish

ABSTRACT A scientific workshop was held in 2006 to discuss the use of in vitro Absorption, Distribution, Metabolism, and Excretion (ADME) data in chemical bioaccumulation assessments for fish. Computer-based (in silico) modeling tools are widely used to estimate chemical bioaccumulation. These in silico methods have inherent limitations that result in inaccurate estimates for many compounds. Based on a review of the science, workshop participants concluded that two factors, absorption and metabolism, represent the greatest sources of uncertainty in current bioaccumulation models. Both factors can be investigated experimentally using in vitro test systems. A variety of abiotic and biotic systems have been used to predict chemical accumulation by invertebrates, and dietary absorption of drugs and xenobiotics by mammals. Research is needed to determine whether these or similar methods can be used to better predict chemical absorption across the gills and gut of fish. Scientists studying mammals have developed a stepwise approach to extrapolate in vitro hepatic metabolism data to the whole animal. A series of demonstration projects was proposed to investigate the utility of these in vitro–in vivo extrapolation procedures in bioaccumulation assessments for fish and delineate the applicability domain of different in vitro test systems. Anticipating research progress on these topics, participants developed a “decision tree” to show how in vitro information for individual compounds could be used in a tiered approach to improve bioaccumulation assessments for fish and inform the possible need for whole-animal testing.

LCA-measured environmental improvements in Pampers® diapers

PurposeThe aim of this study was to investigate the factors that influence the sustainability of disposable baby diapers (nappies) using life cycle assessments (LCAs). Size 4 Pampers® Cruisers (North American name) and ActiveFit (European name) from 2007 are compared to new versions made in 2010 to determine if the design and materials changes intended to improve performance also lead to reductions in the most relevant environmental indicators.Materials and methodsCradle-to-grave LCAs, consistent with ISO 14040/14044 Standards, are conducted. The functional unit is “the number of diapers needed to collect excreta over a child’s diapering lifetime.” Input data come from P&G, suppliers, trade association reports, Franklin and ecoinvent databases, and Google. SimaPro 7 is used to model the LCA. Several life cycle impact assessments (LCIA) methods, sensitivity analyses, normalization to annual consumption, and Monte Carlo analysis are used to produce and check results.Results and discussionThe consumption normalization identified that the diaper’s “environmental footprint” should include the IMPACT2002+ indicators: nonrenewable energy, global warming potential (GWP), respiratory effects from inorganics, total solid waste, and cumulative energy demand (CED). Other indicators are insignificant. Contribution analysis shows that the sourcing and production of diaper materials contribute most to the environmental indicators evaluated, accounting for ∼84% of all non-renewable energy uses and ∼64% of global warming potential. Diaper disposal is a small contributor (1–12%) to potential environmental impacts. Reductions observed for the 2010 US product are: CED—8%, solid waste—12%, non-renewable energy—1%, GWP500—4%, and respiratory inorganics—6%. For the European product, reductions are: CED—11%, solid waste—8%, non-renewable energy—3%, GWP500—5%, and respiratory inorganics—14%.ConclusionsThe new Pampers® diapers sold in the USA and Europe have a reduced environmental footprint versus the previous versions (2007). Significant reductions are achieved in non-renewable energy use and global warming potential, as well as other environmental indicators by optimizing the diaper design and the materials. Although some of the results are single digit reductions, Monte Carlo analysis indicates that there is a high probability that the differences are real. The use of multiple LCIA methods to compare products is helpful to confirm consistency of results. Normalizing the LCIA scores to annual consumption also helps prioritize which environmental indicators can be impactful and affected by changing a product.

Sources of microbial pathogens in municipal solid waste landfills in the United States of America

Municipal solid waste (MSW) categories, as specified by United States Environmental Protection Agency (US EPA), were evaluated for their relative contribution of pathogenic viruses, bacteria, and protozoan parasites into MSW landfills from 1960 to 2007. The purpose of this study was to identify trends and quantify the potential contribution of pathogens in MSW as an aid to the assessment of potential public health risks. A review of the literature was conducted to estimate values for the concentrations of faecal indicator bacteria and pathogens in the major categories of MSW. The major sources of MSW contributing enteric pathogens were food waste, pet faeces, absorbent products, and biosolids. During the last 47 years, recycling of glass, metals, plastic, paper and some organic wastes in MSW has increased, resulting in a decreased proportion of these materials in the total landfilled MSW. The relative proportion of remaining waste materials has increased; several of these waste categories contain pathogens. For all potential sources, food waste contributes the greatest number of faecal coliforms (80.62%). The largest contribution of salmonellae (97.27%), human enteroviruses (94.88%) and protozoan parasites (97%) are expected to come from pet faeces. Biosolids from wastewater treatment sludge contribute the greatest number of human noroviruses (99.94%). By comparison, absorbent hygiene products do not appear to contribute significantly to overall pathogen loading for any group of pathogens. This is largely due to the relatively low volume of these pathogen sources in MSW, compared, for example, with food waste at almost 40% of total MSW.

Organochlorine bioaccumulation and risk for whales in a northwest Atlantic food web

Abstract The poor recovery of multiple whale populations raises concern for the integrity of the US marine environment. Fifty organochlorines were measured in samples of pilot whales, white-sided dolphins, endangered right whales and their prey. As expected from their high trophic position and proximity to land-based sources, the bioaccumulation of 4,4′-DDE, several chlordanes and polychlorinated biphenyl (PCB) congeners was substantial (ppm) in squid and the stranded odontocetes. Concentrations in fish and right whale biopsies were one to two orders of magnitude less than in odontocetes. Although the prevalent pesticides were different between odontocetes and balaenopterids, the magnitude of pesticide concentrations was similar across species. PCB concentrations were higher in the Gulf of Maine dolphins than pilot and right whales. Gender and tissue type were the important characteristics contributing to the bioaccumulation patterns observed in dolphins. Season of sample collection and exposure to different prey seemed critical for the bioaccumulation observed in right and pilot whales. Dolphin and pilot whale organs contained ample concentrations of specific compounds, notably 4,4′-DDE, that have been shown to alter endocrine function.