Key challenges and developments in wildlife ecological risk assessment: Problem formulation

Problem formulation (PF) is a critical initial step in planning risk assessments for chemical exposures to wildlife, used either explicitly or implicitly in various jurisdictions to include registration of new pesticides, evaluation of new and existing chemicals released to the environment, and characterization of impact when chemical releases have occurred. Despite improvements in our understanding of the environment, ecology, and biological sciences, few risk assessments have used this information to enhance their value and predictive capabilities. In addition to advances in organism-level mechanisms and methods, there have been substantive developments that focus on population- and systems-level processes. Although most of the advances have been recognized as being state-of-the-science for two decades or more, there is scant evidence that they have been incorporated into wildlife risk assessment or risk assessment in general. In this article, we identify opportunities to consider elevating the relevance of wildlife risk assessments by focusing on elements of the PF stage of risk assessment, especially in the construction of conceptual models and selection of assessment endpoints that target population- and system-level endpoints. Doing so will remain consistent with four established steps of existing guidance: (1) establish clear protection goals early in the process; (2) consider how data collection using new methods will affect decisions, given all possibilities, and develop a decision plan a priori; (3) engage all relevant stakeholders in creating a robust, holistic conceptual model that incorporates plausible stressors that could affect the targets defined in the protection goals; and (4) embrace the need for iteration throughout the PF steps (recognizing that multiple passes may be required before agreeing on a feasible plan for the rest of the risk assessment). Integr Environ Assess Manag 2024;20:658-673. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Recommendations for further revisions to improve the International Agency for Research on Cancer (IARC) Monograph program

In 2019, the International Agency for Research on Cancer (IARC) "Preamble to the IARC Monographs" expanded guidance regarding the scientific approaches that should be employed in its monographs. These amendments to the monograph development process are an improvement but still fall short in several areas. While the revised Preamble lays out broad methods and approaches to evaluate scientific evidence, there is a lack of specificity with regard to how IARC Working Groups will conduct consistent evaluations in a standardized, objective, and transparent manner; document systematic review and evidence integration actions, and substantiate how these actions and decisions inform the ultimate classifications. Furthermore, no guidance is provided to ensure Working Groups consistently incorporate mechanistic evidence in a robust manner using a defined approach in the context of 21st century knowledge of modes of action. Nor are the conclusions of the working groups subjected to outside, independent scientific peer review. Continued improvements and modernization of the procedures for evaluating, presenting, and communicating study quality, and in the methods used to conduct and peer-review evidence-based decision making will benefit the Working Group members, the IARC Monographs Programme overall, and the international regulatory community and public who rely upon the monographs.

Scientific integrity issues in Environmental Toxicology and Chemistry: Improving research reproducibility, credibility, and transparency

High-profile reports of detrimental scientific practices leading to retractions in the scientific literature contribute to lack of trust in scientific experts. Although the bulk of these have been in the literature of other disciplines, environmental toxicology and chemistry are not free from problems. While we believe that egregious misconduct such as fraud, fabrication of data, or plagiarism is rare, scientific integrity is much broader than the absence of misconduct. We are more concerned with more commonly encountered and nuanced issues such as poor reliability and bias. We review a range of topics including conflicts of interests, competing interests, some particularly challenging situations, reproducibility, bias, and other attributes of ecotoxicological studies that enhance or detract from scientific credibility. Our vision of scientific integrity encourages a self-correcting culture that promotes scientific rigor, relevant reproducible research, transparency in competing interests, methods and results, and education. Integr Environ Assess Manag 2019;00:000-000. © 2019 SETAC.

Benchmark dose analysis framework for developing wildlife toxicity reference values

The effects characterization phase of ecological risk assessments (ERAs) often includes the selection or development of toxicity reference values (TRVs) for chemicals under investigation. In wildlife risk assessments, TRVs are thresholds represented by a dose or concentration associated with a specified adverse response. Traditionally, a TRV may be derived from an estimate of the no-observed-adverse effect level or lowest-observed-adverse-effect level, identified from a controlled toxicity study. Because of the limitations of this approach, risk assessors are increasingly developing TRVs using alternative methods. Benchmark dose (BMD) analysis is widely recognized as one approach for developing TRVs. A BMD is derived using the full dose-response relationship from all experimental doses and may represent a user-specified response level (e.g., 5, 10, 20, or 50%). Although many regulatory programs consider the use of BMD-derived wildlife TRVs, there is limited guidance available for implementing the BMD approach, particularly for ERA. The present study provides a framework for ecological risk assessors to identify appropriate data, examine dose-response relationships, estimate BMDs, and document the results for use in risk analysis. This framework demonstrates the process of developing a TRV using BMD analysis and identifies applications for which this approach may enhance ERAs (e.g., site assessment, chemical or pesticide registration programs). Environ Toxicol Chem 2018;37:1496-1508. © 2018 SETAC.

Human health risk assessment of triclosan in land-applied biosolids

Triclosan (5-chloro-2-[2,4-dichlorophenoxy]-phenol) is an antimicrobial agent found in a variety of pharmaceutical and personal care products. Numerous studies have examined the occurrence and environmental fate of triclosan in wastewater, biosolids, biosolids-amended soils, and plants and organisms exposed to biosolid-amended soils. Triclosan has a propensity to adhere to organic carbon in biosolids and biosolid-amended soils. Land application of biosolids containing triclosan has the potential to contribute to multiple direct and indirect human health exposure pathways. To estimate exposures and human health risks from biosolid-borne triclosan, a risk assessment was conducted in general accordance with the methodology incorporated into the US Environmental Protection Agency's Part 503 biosolids rule. Human health exposures to biosolid-borne triclosan were estimated on the basis of published empirical data or modeled using upper-end environmental partitioning estimates. Similarly, a range of published triclosan human health toxicity values was evaluated. Margins of safety were estimated for 10 direct and indirect exposure pathways, both individually and combined. The present risk assessment found large margins of safety (>1000 to >100 000) for potential exposures to all pathways, even under the most conservative exposure and toxicity assumptions considered. The human health exposures and risks from biosolid-borne triclosan are concluded to be de minimis. Environ Toxicol Chem 2016;35:2358-2367. © 2016 SETAC.

Examination of rare earth element concentration patterns in freshwater fish tissues

Rare earth elements (REEs or lanthanides) were measured in ten freshwater fish species from a reservoir in Washington State (United States). The REE distribution patterns were examined within fillet and whole body tissues for three size classes. Total concentrations (ΣREE) ranged from 0.014 to 3.0 mg kg(-1) (dry weight) and averaged 0.243 mg kg(-1) (dry weight). Tissue concentration patterns indicated that REEs accumulated to a greater extent in organs, viscera, and bone compared to muscle (fillet) tissues. Benthic feeding species (exposed to sediments) exhibited greater concentrations of REEs than pelagic omnivorous or piscivorous fish species. Decreasing REE concentrations were found with increasing age, total length or weight for largescale and longnose suckers, smallmouth bass, and walleye. Concentration patterns in this system were consistent with natural conditions without anthropogenic sources of REEs. These data provide additional reference information with regard to the fate and transport of REEs in freshwater fish tissues in a large aquatic system.

Furthering the derivation of predictive wildlife toxicity reference values for use in soil cleanup decisions

The development of media-specific ecological values for risk assessment includes the derivation of acceptable levels of exposure for terrestrial wildlife (e.g., birds, mammals, reptiles, and amphibians). Although the derivation and subsequent application of these values can be used for screening purposes, there is a need to identify toxicological effects thresholds specifically for making remedial decisions at individual contaminated sites. A workshop was held in the fall of 2012 to evaluate existing methods and recent scientific developments for refining ecological soil screening levels (Eco-SSLs) and improving the derivation of site-specific ecological soil clean-up values for metals (Eco-SCVs). This included a focused session on the development and derivation of toxicity reference values (TRVs) for terrestrial wildlife. Topics that were examined included: methods for toxicological endpoint selection, techniques for dose-response assessment, approaches for cross-species extrapolation, and tools to incorporate environmental factors (e.g., metal bioavailability and chemistry) into a reference value. The workgroup also made recommendations to risk assessors and regulators on how to incorporate site-specific wildlife life history and toxicity information into the derivation of TRVs to be used in the further development of soil cleanup levels.

Efforts to standardize wildlife toxicity values remain unrealized

Wildlife toxicity reference values (TRVs) are routinely used during screening level and baseline ecological risk assessments (ERAs). Risk assessment professionals often adopt TRVs from published sources to expedite risk analyses. The US Environmental Protection Agency (USEPA) developed ecological soil screening levels (Eco-SSLs) to provide a source of TRVs that would improve consistency among risk assessments. We conducted a survey and evaluated more than 50 publicly available, large-scale ERAs published in the last decade to evaluate if USEPA's goal of uniformity in the use of wildlife TRVs has been met. In addition, these ERAs were reviewed to understand current practices for wildlife TRV use and development within the risk assessment community. The use of no observed and lowest observed adverse effect levels culled from published compendia was common practice among the majority of ERAs reviewed. We found increasing use over time of TRVs established in the Eco-SSL documents; however, Eco-SSL TRV values were not used in the majority of recent ERAs and there continues to be wide variation in TRVs for commonly studied contaminants (e.g., metals, pesticides, PAHs, and PCBs). Variability in the toxicity values was driven by differences in the key studies selected, dose estimation methods, and use of uncertainty factors. These differences result in TRVs that span multiple orders of magnitude for many of the chemicals examined. This lack of consistency in TRV development leads to highly variable results in ecological risk assessments conducted throughout the United States.

Survey of fish consumption patterns of King County (Washington) recreational anglers

Three fish consumption surveys were conducted in King County, WA during 1997-2003. These surveys were conducted to support environmental analyses of proposed capital improvement projects planned by the King County Department of Natural Resources and Parks. Personal interviews were conducted at marine, estuarine, and freshwater locations throughout King County. Over 1300 anglers participated in the survey and provided consumption information. A majority of the respondents from the surveys (30-71%) were Caucasian, while the remaining respondents comprised various ethnic groups. The mean consumption rates for consumers of marine fish, shellfish, and freshwater fish were 53, 25, and 10 g/day, respectively. Results indicate that the consumption patterns of marine anglers from King County have remained consistent since the mid-1980s. The consumption distribution for marine anglers suggests that some respondents may consume fish as a large portion of their diet. The consumption habits of freshwater anglers are comparable to those of other recreational anglers throughout the United States. The survey results provide distributions of marine and freshwater fish consumption suitable for risk assessments conducted for anglers residing in King County, WA.

Prenatal methylmercury exposure affects spatial vision in adult monkeys

Decades of research have demonstrated that exposure to methylmercury (MeHg), a ubiquitous environmental pollutant, can have both early and long-term neurobehavioral consequences in exposed offspring. The present study assessed visual functioning in adult macaque monkeys (Macaca fascicularis) exposed in utero to 0, 50, 70, or 90 microg/kg/day of MeHg hydroxide. Twenty-one full-term, normal birth weight offspring (9 controls, 12 exposed) were tested at approximately 11-14.5 years of age on a visual contrast sensitivity task. A forced-choice tracking procedure was utilized with spatial frequencies of 1, 4, 10, and 20 cycles per degree of visual angle. On each test session, a single spatial frequency was presented across five levels of contrast, each differing by 3 dB. Methylmercury-exposed monkeys exhibited reduced contrast sensitivity thresholds, particularly at the higher spatial frequencies. The degree of visual impairment was not related to MeHg body burden or clearance and almost half of the exposed animals were unimpaired. The results from this study demonstrate that chronic in utero MeHg exposure, at subclinical levels, is associated with permanent adverse effects on spatial vision in adult monkeys.