Pollution And Animals

Animals are essential to our lives as humans, they help us with our work, they provide us with company, also have important roles in the environment and feeding. 

With the general increase of environmental contamination, including emerging pollutants and air pollution; the pollutants have been found even in the most remote parts of the earth, such as plastic and nuclear waste found deep in the Mariana Trench. 

The damages caused by pollutants are reported in all ecosystems, land, sea, desert, mountains, rivers, forests, cities, and many more; putting all the living species that inhabit these ecosystems at risk that implies a constant interaction between animals and pollutants, this generates various effects on animals such as changes in behavior, intake of pollutants and damage to their health. Seabirds (Image 1) are one of the most affected species by plastic pollution on beaches and the sea; according to National Geographic, plastic waste is found in the dietary intake of 90 percent of seabirds.

Image 1: Seabirds perch near water; ingest pollutants, so do their chicks.

Let's start with the most dangerous pollutants for oxygen-breathing organisms, the air pollutants. Some organic compounds, also others such as mercury and other heavy metal compounds are present in a large number of places due to human processes, both in the vocational and industrial environment; these compounds can be inhaled by animals and accumulate in their bodies, some of that animals are consumed by people (fish), that's another way these compounds interact with our bodies.

Air pollution is fatal to animals due to its carcinogens and neurotoxic ingredients, domestic and wild animals are at increased risk of developing acute cardiovascular events and the development of coronary artery disease, air pollution is related to DNA mutations, permanent damage, and premature death in animals. The mixture of environmental pollutants is highly harmful, they will harm all air-breathing animals like birds, dogs, tigers, dolphins, ants, beetles, etc. One of the most affected animals by air pollution are the bees, millions of bees are dying and their population has radically decreased worldwide; air pollutants are heavily involved in this situation. 

Some researchers chose several sites in Bangalore that represent high, moderate, low, and rural levels of particulate air pollution and found a lower survival rate of bees at the high and moderate air pollution sites. It's simple... no bees, no food; beetles and other pollinating insects are also negatively affected by air pollution. In Image 2 we see toxic air pollutant particles that cover the leg of a giant bee and are observed through an electron microscope (20 microns). Air pollution is one of the main stressors for bees and harms the behavior, survival, and health of pollinators.

Image 2: A microscopic image of a bee's leg that is covered in pollution.

Another issue is the contribution of pollutant emissions from animals and feeding operations in companies where animals are raised. These operations are related to the deterioration of air quality, in addition to a negative influence on human and environmental health due to emissions of gases such as ammonia (NH3) and hydrogen sulfide (HS), particulate matter (PM), and dangerous volatile organic compounds (VOCs). 

The main pollution from agriculture is ammonia from livestock (poultry, pigs, cattle, and more), as well as fertilization activities and animal feed. Agriculture has become one of the largest contributors to PM2.5 damage in the US, the wrong management of animal waste can damage the water quality on the surface and underground, as well as emit volatile compounds that become part of the pollutant mixture in the air. Pollution is everywhere and in everything, whether in the air or in the form of emerging pollutants. 

Plastic disintegrates over time into small pieces, smaller with time, they can become microscopic particles, making their way to our water sources, the food chain, and even the air we breathe; air pollutants can fall to the ground and invade agricultural fields, surface and groundwater sources in the same way. Millions of marine organisms have been observed to be damaged by emerging pollutants such as entanglement or intake of plastics, from zooplankton, corals, and fish to sea turtles, marine mammals such as whales, and seabirds. 

Consuming plastic can lead to death once an animal's stomach fills with plastic and deteriorate their quality of life, among many other negative effects on animal health. Our oceans are drowning with plastics, the animals that are most affected by this type of pollution are whales, sea turtles, seabirds, fish, humans, all the life involved with oceans and rivers bodies. In Image 3 we see a table that shows the effects caused by pollution in the reproductive system; the table describes the negative effect, the type of pollutant, its source, and the animal where the study was developed. The discussion of this table will be done later below. The discussion of this table will be done later below. 

In addition to individual toxic effects such as cardiovascular and neurotoxic, pollutants also affect biodiversity in a long term; since pollutants have the ability to interact with the sexual apparatus, they cause harm to the offspring of animals and people. As we can see in Image 3, the reported effects on animal reproduction include male feminization, female masculinization, disruption of developmental gonads, biased sexual ratios, altered reproductive timing, reduced sperm motility, decreased fertilization success of inhibited ovules, pheromone productions, masked mating signals, disrupted mate choice and reduced parental care. Although the effects have been found in several different species, not all species are investigated; it must be taken into account that it is because there is a limitation of scientific evidence, no more information has been obtained in other species, also, toxicological studies in humans cannot be performed due to regulations.

Environmental pollution is something that must be solved immediately since every day it is closer to interacting in greater amounts with our body. All sources of pollutants must be attacked at the same time, even progressively to proceed and carry out an equitable elimination of these pollutants and not favor the increase of other contaminants by focusing on a single pollutant. 

Image 3: Reproductive effects of environmental pollutants in animals.

References 

• Aulsebrook, L. C., Bertram, M. G., Martin, J. M., Aulsebrook, A. E., Brodin, T., Evans, J. P., Hall, M. D., O’Bryan, M. K., Pask, A. J., Tyler, C. R., & Wong, B. B. M. (2020). Reproduction in a polluted world: implications for wildlife, Reproduction, 160(2), R13-R23. Retrieved Jun 3, 2021.

• Lavaine, E., Majerus, P. & Treich, N. Health, air pollution, and animal agriculture. Rev Agric Food Environ Stud 101, 517–528 (2020). https://doi.org/10.1007/s41130-020-00124-w

• Claudia Copeland. Air Quality Issues and Animal Agriculture: A Primer. Specialist in Resources and Environmental Policy. December 22, 2014. Congressional Research Service. 7-5700. RL32948

• Rocha, José & Almeida, Josimar & Lins, Gustavo & Durval, Alberto. (2011). INSECTS AS INDICATORS OF ENVIRONMENTAL CHANGING AND POLLUTION: A REVIEW OF APPROPRIATE SPECIES AND THEIR MONITORING. Holos Environment. 10. 10.14295/holos.v10i2.2996. 

• Thimmegowda GG, Mullen S, Sottilare K, Sharma A, Mohanta SS, Brockmann A, Dhandapany PS, Olsson SB. A field-based quantitative analysis of sublethal effects of air pollution on pollinators. Proc Natl Acad Sci U S A. 2020 Aug 25;117(34):20653-20661. doi: 10.1073/pnas.2009074117. Epub 2020 Aug 10. PMID: 32778582; PMCID: PMC7456092.