Barnett A. Rattner

History of wildlife toxicology.

The field of wildlife toxicology can be traced to the late nineteenth and early twentieth centuries. Initial reports included unintentional poisoning of birds from ingestion of spent lead shot and predator control agents, alkali poisoning of waterbirds, and die-offs from maritime oil spills. With the advent of synthetic pesticides in the 1930s and 1940s, effects of DDT and other pesticides were investigated in free-ranging and captive wildlife. In response to research findings in the US and UK, and the publication of Silent Spring in 1962, public debate on the hazards of pollutants arose and national contaminant monitoring programs were initiated. Shortly thereafter, population-level effects of DDT on raptorial and fish-eating birds were documented, and effects on other species (e.g., bats) were suspected. Realization of the global nature of organochlorine pesticide contamination, and the discovery of PCBs in environmental samples, launched long-range studies in birds and mammals. With the birth of ecotoxicology in 1969 and the establishment of the Society of Environmental Toxicology and Chemistry in 1979, an international infrastructure began to emerge. In the 1980s, heavy metal pollution related to mining and smelting, agrichemical practices and non-target effects, selenium toxicosis, and disasters such as Chernobyl and the Exxon Valdez dominated the field. Biomarker development, endocrine disruption, population modeling, and studies with amphibians and reptiles were major issues of the 1990s. With the turn of the century, there was interest in new and emerging compounds (pharmaceuticals, flame retardants, surfactants), and potential population-level effects of some compounds. Based upon its history, wildlife toxicology is driven by chemical use and misuse, ecological disasters, and pollution-related events affecting humans. Current challenges include the need to more thoroughly estimate and predict exposure and effects of chemical-related anthropogenic activities on wildlife and their supporting habitat.

Assessment of toxicity and potential risk of the anticoagulant rodenticide diphacinone using Eastern screech-owls (Megascops asio)

In the United States, new regulatory restrictions have been placed on the use of some second-generation anticoagulant rodenticides. This action may be offset by expanded use of first-generation compounds (e.g., diphacinone; DPN). Single-day acute oral exposure of adult Eastern screech-owls (Megascops asio) to DPN evoked overt signs of intoxication, coagulopathy, histopathological lesions (e.g., hemorrhage, hepatocellular vacuolation), and/or lethality at doses as low as 130xa0mg/kg body weight, although there was no dose–response relation. However, this single-day exposure protocol does not mimic the multiple-day field exposures required to cause mortality in rodent pest species and non-target birds and mammals. In 7-day feeding trials, similar toxic effects were observed in owls fed diets containing 2.15, 9.55 or 22.6xa0ppm DPN, but at a small fraction (<5%) of the acute oral dose. In the dietary trial, the average lowest-observed-adverse-effect-level for prolonged clotting time was 1.68xa0mg DPN/kg owl/week (0.24xa0mg/kg owl/day; 0.049xa0mg/owl/day) and the lowest lethal dose was 5.75xa0mg DPN/kg owl/week (0.82xa0mg/kg owl/day). In this feeding trial, DPN concentration in liver ranged from 0.473 to 2.21xa0μg/g wet weight, and was directly related to the daily and cumulative dose consumed by each owl. A probabilistic risk assessment indicated that daily exposure to as little as 3–5xa0g of liver from DPN-poisoned rodents for 7xa0days could result in prolonged clotting time in the endangered Hawaiian short-eared owl (Asio flammeus sandwichensis) and Hawaiian hawk (Buteo solitarius), and daily exposure to greater quantities (9–13xa0g of liver) could result in low-level mortality. These findings can assist natural resource managers in weighing the costs and benefits of anticoagulant rodenticide use in pest control and eradication programs.

Potential Hazards of Environmental Contaminants to Avifauna Residing in the Chesapeake Bay Estuary

Abstract A search of the Contaminant Exposure and Effects-Terrestrial Vertebrates (CEE-TV) database revealed that 70% of the 839 Chesapeake Bay records deal with avian species. Studies conducted on waterbirds in the past 15 years indicate that organochlorine contaminants have declined in eggs and tissues, although p,p’-DDE, total polychlorinated biphenyls (PCBs) and coplanar PCB congeners may still exert sublethal and reproductive effects in some locations. There have been numerous reports of avian die-off events related to organophosphorus and carbamate pesticides. More contemporary contaminants (e.g., alkylphenols, ethoxylates, perfluorinated compounds, polybrominated diphenyl ethers) are detectable in bird eggs in the most industrialized portions of the Bay, but interpretation of these data is difficult because adverse effect levels are incompletely known for birds. Two moderate-sized oil spills resulted in the death of several hundred birds, and about 500 smaller spill events occur annually in the watershed. With the exception of lead, concentrations of cadmium, mercury, and selenium in eggs and tissues appear to be below toxic thresholds for waterbirds. Fishing tackle and discarded plastics, that can entangle and kill young and adults, are prevalent in nests in some Bay tributaries. It is apparent that exposure and potential effects of several classes of contaminants (e.g., dioxins, dibenzofurans, rodenticides, pharmaceuticals, personal care products, lead shot, and some metals) have not been systematically examined in the past 15 years, highlighting the need for toxicological evaluation of birds found dead, and perhaps an avian ecotoxicological monitoring program. Although oil spills, spent lead shot, some pesticides, and industrial pollutants occasionally harm Chesapeake avifauna, contaminants no longer evoke the population level effects that were observed in Ospreys (Pandion haliaetus) and Bald Eagles (Haliaeetus leucocephalus) through the 1970s.

Management Concerns about Known and Potential Impacts of Lead Use in Shooting and in Fishing Activities

Abstract We present a summary of the technical review, jointly requested by the American Fisheries Society and The Wildlife Society, addressing the hazards to wildlife resulting from lead objects or fragments introduced into aquatic and terrestrial environments from the use of ammunition and fishing tackle. Impacts from lead are well documented in humans, as well as in terrestrial and aquatic organisms. Concern about impacts from lead ammunition and fishing tackle has resulted in the development of non-lead alternatives, educational campaigns, and regulations to restrict their use. This article discusses the general biological impacts of lead exposure from fishing and shooting activities to fish, wildlife, and humans; summarizes existing and proposed regulations to reduce lead exposure to biota; reviews alternatives to lead materials that are currently available for fishing; and outlines options for further actions to reduce wildlife and human exposure to lead from fishing activities.

Element Patterns in Feathers of Nestling Black-Crowned Night-Herons, Nycticorax nycticorax L., from Four Colonies in Delaware, Maryland, and Minnesota

The pattern of elements in nestling black-crowned night-heron feathers from a rural Minnesota colony differed from colonies in industrialized regions of Maryland and Delaware. Except for chromium, however, the differences did not reflect the elements associated with waters and sediments of the Maryland and Delaware colonies. Therefore, elements in water and sediment do not necessarily bioaccumulate in night-heron feathers in relation to potential exposure. Although trace element patterns in feathers indicated differences among geographical locations, they did not separate all locations well and their usefulness as an indicator of natal colony location may be limited.

Predictive framework for estimating exposure of birds to pharmaceuticals

We present and evaluate a framework for estimating concentrations of pharmaceuticals over time in wildlife feeding at wastewater treatment plants (WWTPs). The framework is composed of a series of predictive steps involving the estimation of pharmaceutical concentration in wastewater, accumulation into wildlife food items, and uptake by wildlife with subsequent distribution into, and elimination from, tissues. Because many pharmacokinetic parameters for wildlife are unavailable for the majority of drugs in use, a read-across approach was employed using either rodent or human data on absorption, distribution, metabolism, and excretion. Comparison of the different steps in the framework against experimental data for the scenario where birds are feeding on a WWTP contaminated with fluoxetine showed that estimated concentrations in wastewater treatment works were lower than measured concentrations; concentrations in food could be reasonably estimated if experimental bioaccumulation data are available; and read-across from rodent data worked better than human to bird read-across. The framework provides adequate predictions of plasma concentrations and of elimination behavior in birds but yields poor predictions of distribution in tissues. The approach holds promise, but it is important that we improve our understanding of the physiological similarities and differences between wild birds and domesticated laboratory mammals used in pharmaceutical efficacy/safety trials, so that the wealth of data available can be applied more effectively in ecological risk assessments. Environ Toxicol Chem 2017;36:2335-2344.