The role of toxicology in wildlife conservation

Introduction
Plastic pollution
Industrial chemicals
Pesticide toxicity
References
Further reading

Wildlife toxicology involves the study of how various environmental pollutants can alter the physiology and anatomy of wildlife. Such effects can determine the overall fitness and survival of these animals by affecting their reproductive success, health and general well-being in the wild.

Animals in the wild can be exposed to various harmful pollutants through the food and water they consume, the air they breathe, and the environment in which they live. Scientists around the world have made significant progress in understanding how the presence of various environmental pollutants can create challenges in wildlife conservation efforts. This research has supported efforts to ultimately establish measures to prevent the negative effects of this pollution in nature.

Plastic pollution

Recent estimates suggest that at least 14 million tons of plastic are dumped into the ocean each year. With around 80% of water waste consisting of plastic pollutants, marine wildlife is inevitably affected, threatening the health and safety of many of the world’s food resources.

In the past, researchers have primarily been interested in documenting plastic ingestion by animals, rather than focusing on the effects that plastic ingestion has on marine wildlife. By shifting their focus, researchers can expand their understanding of the physical and toxicological symptoms that plastic ingestion can have on individual organisms, as well as its population effects on marine wildlife.

By understanding the impact of plastic ingestion at the marine population level, researchers can begin to elucidate the degree to which animals are exposed to certain pollutants. Furthermore, this information will provide new insights into the reproductive toxicity profile of these pollutants on different organisms.

In addition to determining the impact of plastic ingestion at both the population and organismal levels, toxicologists are also interested in determining how various biological factors may affect the susceptibility of certain wildlife to the effects of plastic ingestion. As a result, researchers were able to identify animal populations that should be targeted for both research and conservation efforts.

Industrial chemicals

Despite the implementation of both national and international bans as well as regulations on the release of various industrial chemicals into the environment, the levels of these pollutants in various parts of the world, especially the Arctic, remain constantly high. In addition to previously detected chemicals, new and surrogate chemicals have also been detected in the Arctic and have been described as Chemicals of Emerging Arctic Concern (CEACs). Although some of the CEACs identified to date are considered to be less persistent than previous persistent organic pollutants (POPs), the distinct physicochemical properties of these chemicals have raised concerns regarding their potentially harmful biological effects.

Perfluorooctanesulfonic acid (PFOS) and hexabromocyclododecane (HBCDD) are two types of CEACs that have high toxic potentials and have been identified throughout the Arctic. The accumulation of these chemicals, in addition to older POPs that have also been detected in high concentrations in Arctic top predators, has increased the complexity of understanding their combined effects on wildlife.

Indeed, the presence of both POPs and CEACs in arctic wildlife increases the likelihood of their cumulative and/or synergistic effects on exposed wildlife. This can lead to a wide range of immune, reproductive and neuroendocrine effects on these organisms.

Taken together, toxicological research into these compounds in Arctic wildlife, especially top predators, is needed to understand the transport of these chemicals into Arctic food webs and whether their levels are increasing, decreasing, or remaining the same. This information will subsequently provide insight into how the accumulation of these chemicals can threaten Arctic biodiversity.

Pesticide toxicity

The widespread use of pesticides throughout the world has inevitably increased wildlife exposure to these chemicals. Although there are various media that can be used to monitor pesticide contamination, the airborne dispersion of these chemicals remains a challenge for toxicological assessments.

Pesticides often contaminate the air either through volatilization of pesticide droplets before they reach their target, drift of vapors after pesticide application from the target area, or due to wind carrying contaminated soil particles to off-target locations.

In addition to their risk of breathing air that has been contaminated with pesticides, wildlife can also be exposed to these chemicals through the ingestion of leaves that have been contaminated as a result of pesticide operations. Although wildlife is unlikely to suffer acute toxicity from this route of exposure, chronic toxicity can cause a wide range of sublethal effects on wildlife that can affect various organ systems as well as their offspring.

References

• Barton, CC, & Ainerua, MO (2020). Chapter 30 – Environmental toxicology: wildlife. Information Resources in Toxicology (Fifth Edition); 337-344. doi:10.1016/B978-0-12-813724-6.00030-X.
• Avery-Gomm, S., Borrelle, SB, & Provencher, JF (2018). Linking plastic ingestion research with marine wildlife conservation. Science of the Total Environment 637-638; 1492-1495. doi:10.1016/j.scitotenv.2018.04.409.
• Sonne, C., Dietz, R., Jenssen, BM, et al. (2021). New pollutants and biological effects in Arctic wildlife. Trends in Ecology and Evolution 36(5); 421-429. doi:10.1016/j.tree.2021.01.007.
• Zaller, JG, Kruse-Pla, M., Schlectgurt, U., et al. (2022). Pesticides in the ambient air, influenced by surrounding land use and weather, pose a potential threat to biodiversity and people. Science of the total environment 838(2). doi:10.1016/j.scietotenv.2022.156012.

Further reading