Environmental Toxins

Right Whale in Green Tide Photo
Southern right whale swimming in algal bloom "soup" off the Patagonia coast.
©Mariano Sironi

Wildlife—and humans—are exposed to toxins via air, water, land, and food. People are responsible for introducing many types of toxins into the environment through industrial emissions, pesticides, medications, fertilizers, oil spills, sewage, garbage, and even lead bullets. The effects of toxins on wildlife can be difficult to ascertain and, usually, harder to remedy. Once toxins enter the environment, they accumulate in the food chain, affecting all levels of the ecosystem. Understanding the intricacies of these systems and the effects of these contaminants often requires extensive scientific research, and many years and conservation dollars to reverse.


  • Identify the origins and effects of toxins in the environment
  • Mitigate the influence of toxins on wildlife and humans

What WCS is Doing

Mercury: Coal-burning power plants emit mercury particles, which can fall into bodies of water and become methylmercury, a harmful neurotoxin. Microorganisms consume the particles, which then travel up the food chain and accumulate in the bodies of fish in progressively higher concentrations at each step. Animals that consume large amounts of fish—such as common loons and humans—often have high levels of mercury in their system.

WCS health experts annually monitor loons in Adirondack Park, New York. They have found that loons with high levels of mercury fledge about 40 percent fewer chicks than loons with low mercury levels.

Lead: Lead gunshot can harm animals even when hunters miss their target. This is particularly important in the case of waterfowl, which accidentally ingest spent lead pellets, which they confuse with seeds or grit. Over time, the pellets dissolve in their stomachs, and lead accumulates in the animals’ bones. This slow and progressive lead intoxication may be less obvious than immediate fatal lead poisonings, but it has a significant impact on the animals’ health, affecting their fitness and reproductive success. The effects of lead are also seen up the food chain, particularly in scavengers that feed on carcasses laced with this toxin.

WCS-Global Health scientists are examining ducks in Argentina’s Santa Fe Province to assess the extent of wild waterbird exposure to lead via spent ammunition in the environment. They hope to mitigate lead’s impact on waterfowl and the ecosystem by creating policies for the replacement of lead ammunition.

Diclofenac: During the 1990s in South Asia, diclofenac, an anti-inflammatory drug normally used to treat humans, was introduced for veterinary use in the treatment of livestock. Religious and cultural taboos across much of the Indian subcontinent prohibit the consumption of dead livestock. The carcasses are left to scavengers such as vultures. Unfortunately, vultures are unusually sensitive to the toxic effects of diclofenac. Birds that consume quantities of treated livestock suffer kidney failure and die within days. As a result, populations of at least five vulture species have crashed during the past decade; four are considered Critically Endangered. Despite the availability of alternative drugs, the use of diclofenac continues in parts of South Asia, Africa, and Afghanistan.

WCS field vets are working to monitor the availability of diclofenac in Afghanistan and to encourage farmers to switch to alternatives (such as meloxicam) that are safe for vultures.

Harmful Algal Blooms (HABs): When certain types of marine algae bloom in high densities, they produce toxins that can affect marine animals and humans. Thousands of fish and seabirds may die, and sea turtles and mammals may become sick or stranded, or die. Such algal blooms can force authorities to close poisoned local fisheries that people depend on. While HABs occur naturally, pollution of the marine environment by fertilizer run-off and sewage as well as severe weather events and climate change might be causing HABs to occur more frequently and with increased severity.

WCS field vets are monitoring populations of seabirds and marine mammals around the southern tip of South America to ascertain their exposure to HAB toxins. The WCS-Global Health program is also spreading awareness of how HABs may occur more often, and in more places, as a result of climate change.

From the Newsroom

Mercury Sickens Adirondack LoonsJune 28, 2012

Loons nesting and raising their young in the New York Adirondacks are increasingly threatened by mercury contamination, which impacts reproduction and behavior. A new scientific report on Adirondack loons emphasizes the importance of reducing mercury in the atmosphere.

Getting the Lead Out August 31, 2011

Sante Fe is the first province in Argentina to take steps toward cutting allowable amounts of lead ammunition used for hunting. WCS commends the effort and hopes others will follow their lead against lead pollution.

Rare Vulture Returns to Cambodian SkiesMarch 18, 2009

After nearly dying from eating a poisoned animal carcass, a critically endangered white-rumped vulture was nursed back to health by wildlife veterinarians and conservationists from WCS and Angkor Centre for Conservation of Biodiversity.

Adirondack Alarm CallMarch 7, 2008

A long-term study by the Wildlife Conservation Society, the BioDiversity Research Institute, and other organizations has found and confirmed that environmental mercury—much of which comes from human-generated emissions—is impacting the health and reproductive success of common loons in the northeastern U.S.

On the iPod of an Ibis: Mood Music

To help save a species in the wild, zookeepers make a romantic mix tape for the Bronx Zoo’s endangered Waldrapp ibises.

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