19
Aug
Dolphins Stranded Along Eastern Seaboard Are Diseased, Contaminated with Pesticides, Plastics, Disinfectants, and Heavy Metals
(Beyond Pesticides, August 19, 2020) Stranded dolphins and whales along the United States Eastern Seaboard contain herbicides, disinfectants, plastics, and heavy metals, research published in Frontiers of Marine Science finds. The witches brew of toxins is likely contributing to ill health among these ecologically important, intelligent, and charismatic species, and may be playing a role in the occurrence of strandings. “It’s really hard to judge, when an animal strands, if the toxins in the animal were related to why it stranded,” said James Sullivan, PhD, executive director of Harbor Branch Oceanographic Institute in Florida, which participated in the study, to UPI. “But these health problems do stack up. The animal is much more susceptible to succumbing to natural disease and environmental problems, just like humans are more likely to get ill from coronavirus if they have underlying conditions.”
Dr. Sullivan’s statement rings true across a range of impacts resulting from chemical exposure or other stressors – while an individual may not be killed outright, weakening that occurs after exposure can significantly affect long term fitness in the wild. Eventually, these effects can add up to significant population declines. Unfortunately, this phenomenon in the natural world is often presented as “mysterious” by the press. Concern over toxic exposures are often glossed over in the context of a regulatory system that focuses primarily on acute effects, permits certain levels of risk from exposure, and continues to neglect full accounting of the externalities caused by chemical use.
In order to understand the range of stressors dolphins had been exposed to, researchers collected tissue samples in coordination with existing marine mammal stranding networks along the East Coast. Over 60 blubber and liver samples from 83 different animals were tested in the lab for the herbicide atrazine, antimicrobial disinfectant triclosan, concentrations of PCB, bisphenol-A (BPA), diethyl phthalates, nonylphenol monoethoxylate [NPE], and a range of heavy metals, including arsenic, mercury, cadmium, and lead.
Bottlenose dolphins were found to have high levels of triclosan in their bodies, second only to BPA. Both dolphins and pygmy sperm whales tested had lower levels of atrazine, but detections were not insignificant. Triclosan, atrazine, and BPA have each been shown to disrupt the endocrine (hormonal) system in a range of animals, including mammals, at infinitesimally small levels of exposure. However, the U.S. Environmental Protection Agency has yet to regulate chemicals for this criteria, despite an over 20 year old mandate from Congress to do so.
Levels of other harmful compounds, such as heavy metals, were also of concern. These exposures appear to differ based on location. For example, dolphins found stranded along the Florida coast are more likely to contain high levels of lead and mercury when compared to dolphins found along North Carolina. The difference is likely attributed to habitat. Dolphins stranded in North Carolina likely spend most of their lives in the open ocean, while a number of Florida dolphin populations live and feed near the shore, where they are more exposed to human runoff and pollution.
“Some of the mercury levels we found were the highest found anywhere in the world,” said study coauthor Justin Perrault, PhD. “It is eye-opening. To see the levels of some of these contaminants is alarming.”
Researchers also looked at tissue samples for evidence of disease, documenting abnormal cell growth, hepatitis, fibrosis, and disfunction in the lymphatic system and thyroid glands. In sum, the data appear to indicate that many dolphins are likely dealing with a range of underlying health conditions prior to the stranding incident that killed them.
The present study is the first to observe and detect certain chemicals like atrazine in the bodies of dolphins and whales, but several prior studies have shown cause for concern. As far back as 2009, scientists had detected triclosan in bottlenose dolphins sampled in Florida and South Carolina. Two studies, one published in 2016 and another in 2019, found dolphins along the Eastern Seaboard carrying chemicals considered to be trade secrets by the pesticide industry.
“We must do our part to reduce the amount of toxicants that enter into our marine environment, which have important health and environmental implications not just for marine life but for humans,” said Page-Karjian, PhD, lead author and researcher from the Harbor Branch Oceanographic Institute at the Florida Atlantic University, in a press release. “These chemicals work their way up through the food chain and get more concentrated the higher up they go. When dolphins and whales eat fish with concentrations of the chemicals, the toxic elements enter their bodies. Dolphins eat a variety of fish and shrimp in these marine environments and so do humans.”
In many ways, animals are acting as sentient species for chemical contamination. Unless more is done to address this pollution, humans are likely to see similar declines in general health, fitness, and well-being. We cannot simply continue observe while ecosystems are poisoned – science points the way, but it is the job of informed residents of the United States to act in a way that protects public health and the wider environment. Learn more about the dangers pesticides pose to wildlife and what you can do through Beyond Pesticides’ wildlife program page.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Frontiers in Marine Science, UPI
