Using emerging science to inform risk characterizations for wildlife within current regulatory frameworks.

Many jurisdictions have regulatory frameworks that seek to reduce the effects of environmental exposures of anthropogenic chemicals on terrestrial wildlife (i.e., mammals, birds, reptiles, and amphibians).

Advancing exposure assessment approaches to improve wildlife risk assessment.

The exposure assessment component of a Wildlife Ecological Risk Assessment aims to estimate the magnitude, frequency, and duration of exposure to a chemical or environmental contaminant, along with characteristics of the exposed population. This can be challenging in wildlife as there is often high uncertainty and error caused by broad-based, interspecific extrapolation and assumptions often because of a lack of data. Both the US Environmental Protection Agency (USEPA) and European Food Safety Authority (EFSA) have broadly directed exposure assessments to include estimates of the quantity (dose or concentration), frequency, and duration of exposure to a contaminant of interest while considering "all relevant factors.

Challenges with the current methodology for conducting Endangered Species Act risk assessments for pesticides in the United States.

The US Environmental Protection Agency (USEPA or the Agency) is responsible for administering the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The Agency is also required to assess the potential risks of pesticides undergoing registration or re-registration to threatened and endangered (i.e.

ESASeedPARAM: A seed treatment model for threatened and endangered bird species in the United States.

The USEPA, National Marine Fisheries Service, and Fish and Wildlife Service are required to assess the risks of pesticides undergoing registration or reregistration to threatened and endangered (i.e., listed) species.

Utility of the avian sub-acute dietary toxicity test in ecological risk assessment and a path forward to reduce animal use.

The United States Environmental Protection Agency (USEPA) has long required both avian sub-acute dietary and acute oral studies to inform risk assessments for pesticides. Recently, the USEPA collaborated with People for the Ethical Treatment of Animals to determine whether the results of the acute oral avian toxicity test or the sub-acute dietary toxicity test consistently generated the greatest risk predictions in USEPA tier 1 assessments for pesticides first registered between 1998 and 2017. Their study concluded that in 99% of the cases, risk conclusions were driven by the acute oral study (OPPTS 850.

A field spray drift study to determine the downwind effects of isoxaflutole herbicide to nontarget plants.

Spray drift buffers are often required on herbicide labels to prevent potential drift effects to nontarget plants. Buffers are typically derived by determining the distance at which predicted exposure from spray drift equals the ecotoxicology threshold for sensitive plant species determined in greenhouse tests. Field studies performed under realistic conditions have demonstrated, however, that this approach is far more conservative than necessary.

Integrating Exposure and Effect Distributions with the Ecotoxicity Risk Calculator: Case Studies with Crop Protection Products.

Risk curves describe the relationship between cumulative probability and magnitude of effect and thus express far more information than risk quotients. However, their adoption has remained limited in ecological risk assessment. Therefore, we developed the Ecotoxicity Risk Calculator (ERC) to simplify the derivation of risk curves, which can be used to inform risk management decisions.

Correcting for Phylogenetic Autocorrelation in Species Sensitivity Distributions.

A species sensitivity distribution (SSD) is a cumulative distribution function of toxicity endpoints for a receptor group. A key assumption when deriving an SSD is that the toxicity data points are independent and identically distributed (iid). This assumption is tenuous, however, because closely related species are more likely to have similar sensitivities than are distantly related species.

A probabilistic risk assessment for the Kirtland's warbler potentially exposed to chlorpyrifos and malathion during the breeding season and migration.

Two organophosphate pesticides, chlorpyrifos and malathion, are currently undergoing reregistration in the United States and were recently used by the US Environmental Protection Agency (USEPA) as case studies to develop a national procedure for evaluating risks to endangered species. One of the endangered bird species considered by the USEPA was the Kirtland's warbler (Setophaga kirtlandii). The Kirtland's warbler is an endangered migratory species that nests exclusively in young jack pine stands in Michigan and Wisconsin, and winters in the Bahamas.

A refined ecological risk assessment for California red-legged frog, Delta smelt, and California tiger salamander exposed to malathion.

The California red-legged frog (CRLF), Delta smelt (DS), and California tiger salamander (CTS) are 3 species listed under the United States Federal Endangered Species Act (ESA), all of which inhabit aquatic ecosystems in California. The US Environmental Protection Agency (USEPA) has conducted deterministic screening-level risk assessments for these species potentially exposed to malathion, an organophosphorus insecticide and acaricide. Results from our screening-level analyses identified potential risk of direct effects to DS as well as indirect effects to all 3 species via reduction in prey.

A weight-of-evidence approach for deriving a level of concern for atrazine that is protective of aquatic plant communities.

Atrazine is a selective triazine herbicide widely used in the United States primarily for control of broadleaf weeds in corn and sorghum. In 2003, the US Environmental Protection Agency (USEPA) concluded that atrazine poses potential risks to sensitive aquatic species. Consequently, a surface water monitoring program was developed to assess whether measured levels of atrazine could impact aquatic plants in vulnerable watersheds.

Ecological risk assessment for aquatic invertebrate communities exposed to imidacloprid as a result of labeled agricultural and nonagricultural uses in the United States.

A probabilistic ecological risk assessment (ERA) was conducted to determine the potential effects of acute and chronic exposure of aquatic invertebrate communities to imidacloprid arising from labeled agricultural and nonagricultural uses in the United States. Aquatic exposure estimates were derived using a higher-tier refined modeling approach that accounts for realistic variability in environmental and agronomic factors. Toxicity was assessed using refined acute and chronic community-level effect metrics for aquatic invertebrates (i.

Ecological risk assessment for Pacific salmon exposed to dimethoate in California.

A probabilistic risk assessment of the potential direct and indirect effects of acute dimethoate exposure to salmon populations of concern was conducted for 3 evolutionarily significant units (ESUs) of Pacific salmon in California. These ESUs were the Sacramento River winter-run chinook, the California Central Valley spring-run chinook, and the California Central Valley steelhead. Refined acute exposures were estimated using the Soil and Water Assessment Tool, a river basin-scale model developed to quantify the impact of land-management practices in large, complex watersheds.

Ecological risk assessment for mink and short-tailed shrew exposed to PCBs, dioxins, and furans in the Housatonic River area.

A probabilistic risk assessment was conducted to characterize risks to a representative piscivorous mammal (mink, Mustela vison) and a representative carnivorous mammal (short-tailed shrew, Blarina brevicauda) exposed to PCBs, dioxins, and furans in the Housatonic River area downstream of the General Electric (GE) facility in Pittsfield, Massachusetts. Contaminant exposure was estimated using a probabilistic total daily intake model and parameterized using life history information of each species and concentrations of PCBs, dioxins, and furans in prey collected in the Housatonic River study area. The effects assessment preferentially relied on dose-response curves but defaulted to benchmarks or other estimates of effect when there were insufficient toxicity data.

Risk assessment considerations with regard to the potential impacts of pesticides on endangered species.

Simple, deterministic screening-level assessments that are highly conservative by design facilitate a rapid initial screening to determine whether a pesticide active ingredient has the potential to adversely affect threatened or endangered species. If a worst-case estimate of pesticide exposure is below a very conservative effects metric (e.g.

Refined avian risk assessment for chlorpyrifos in the United States.

Refined risk assessments for birds exposed to flowable and granular formulations ofCPY were conducted for a range of current use patterns in the United States. Overall,the collective evidence from the modeling and field study lines of evidence indicate that flowable and granular CPY do not pose significant risks to the bird communities foraging in agro-ecosystems in the United States. The available information indicates that avian incidents resulting from the legal, registered uses of CPY have been very infrequent since 2002 (see SI Appendix 3).

Risks of carbamate and organophosphate pesticide mixtures to salmon in the Pacific Northwest.

Salmon populations in the Pacific Northwest are being affected by a variety of environmental stressors including intense fishing pressure, parasites and disease, climatic variability and change, land development, hatchery production, hydropower operations, stormwater runoff, and exposure to toxic contaminants. In recent years, there has been much concern that mixtures of pesticides are causing toxic effects to Pacific salmon. In this study, we compared measured stream water concentrations from 2 monitoring studies conducted in the Pacific Northwest with concentration-response curves derived for inhibition of brain acetylcholinesterase activity in juvenile coho salmon (Oncorhynchus kisutch) for mixtures of organophosphate (OPs) and carbamate (CBs) pesticides.

Baseline ecological risk assessment of the Calcasieu Estuary, Louisiana: Part 1. Overview and problem formulation.

A remedial investigation/feasibility study (RI/FS) of the Calcasieu Estuary cooperative site was initiated in 1998. This site, which is located in the southwestern portion of Louisiana in the vicinity of Lake Charles, includes the portion of the estuary from the saltwater barrier on the Calcasieu River to Moss Lake. As part of the RI/FS, a baseline ecological risk assessment (BERA) was conducted to assess the risks to aquatic organisms and aquatic-dependent wildlife exposed to environmental contaminants.

Probabilistic risk-assessment model for birds exposed to granular pesticides.

For granular formulations of pesticides, direct consumption by birds is generally the most important route of exposure. A probabilistic exposure model was developed that estimates how many pesticide granules a bird ingests and, from that, the quantity of pesticide ingested. This model, referred to as the "granular pesticide avian risk assessment model" (GranPARAM), has input variables not included in current screening-level assessments for granular pesticides, such as proportion of time for which birds forage in the field, grit ingestion rates, attractiveness of pesticide granules compared with natural grit, and proportions of soil particles and pesticide granules in the size range consumed by birds.

Refined aquatic risk assessment for aldicarb in the United States.

Aldicarb is a systemic insecticide applied directly to soil and to control mites, nematodes, and aphids on a variety of crops (e.g., cotton, potatoes, peanuts).

Refined avian risk assessment for aldicarb in the United States.

Aldicarb was recently reviewed by the US Environmental Protection Agency (USEPA) for re-registration eligibility. In this paper, we describe a refined avian risk assessment for aldicarb that was conducted to build upon the screening-level methods used by USEPA. The goal of the refined ERA was to characterize and understand better the risks posed by aldicarb to birds in areas where the pesticide is applied.

Evaluation of sources of uncertainty in risk assessments conducted for the US Army using a case study approach.

We identify, categorize, and score sources of uncertainty in human health and ecological risk assessments conducted for several US Army sites to identify better analytical practices and opportunities for targeted research to improve risk estimates. The reviewed assessments are from reports completed within the past 8 y and were obtained from the US Army Environmental Technical Information Center (ETIC) at Aberdeen Proving Ground, Maryland, USA. Most of the risk assessments incorporated only qualitative uncertainty analysis to demonstrate the conservatism of selected data and predictive models.