An analysis of 83 dolphins and whales that were found stranded on beaches across the United States from 2012 to 2018 has shown that their blubber contained concerning levels of toxic pollutants. The findings, published in the journal Frontiers in Marine Science, revealed that pollutants from herbicides, food packaging, toothpaste, soap, detergents, and toys had made their way into the tissues of the dead cetaceans. It’s also the first study of its kind both in reporting on pollutant concentrations in blubber and including data on the white-beaked dolphin and Gervais’ beaked whale, two species for which the scientific record is still notably sparse.
Led by researchers from Florida Atlantic University's (FAU) Harbor Branch Oceanographic Institute, the study analyzed blubber samples to measure the concentration of five organic toxicants including atrazine, DEP, NPE, bisphenol-A, diethyl phthalates, and triclosan. This data was complemented with liver sample analyses measuring the presence of elements and a toxic industrial compound.
The analyses showed that several factors influenced the concentration of toxins and elements in the cetacean’s blubber, including species, sex, age, and location. For example, bottlenose dolphins had much higher concentrations of lead, manganese, mercury, selenium, thallium, and zinc in their livers while pygmy and sperm whales had higher levels of NPE, arsenic, cadmium, cobalt, and iron. In female bottlenose dolphins, arsenic was the most concerning element, as they contained significantly higher concentrations compared to adult males.
Furthermore, the blubber samples taken from dolphins that beached in Florida were found to contain much higher levels of lead, mercury, and selenium, but lower concentrations of iron when compared to those stranded in North Carolina. This disparity demonstrates the significance of geography in the dolphins' health and shows how changes in the marine environment can greatly impact an animal’s health.
The researchers state that these toxic pollutants made their way into the marine environment either in the form of polluted runoff and chemicals from fossil fuels and single-use plastics used by humans that made it into the waterways. The specific chemicals detected were linked to food packaging, detergents, and even children's toys, some of which contain dangerous phthalates.
"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 Dr Annie Page-Karjian, an assistant research professor and clinical veterinarian at FAU's Harbor Branch, in a statement. "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."
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