“Any animals in the near-shore environment with similar prey are probably being exposed as well.”
(Beyond Pesticides) Bottlenose dolphins found along Florida’s west coast contain detectable levels of phthalates, chemicals used in plastics, cosmetics and as inert ingredients in pesticide products, research published in the journal GeoHealth last month indicates. The study, published by scientists from the College of Charleston, South Carolina, is the first to find detectable levels of these toxic industrial byproducts in dolphins. Given the transient nature of urinary detection, the findings indicate that dolphins and other marine mammals are at increased risk of health effects related to phthalate exposure.
Scientists sampled a total of 17 dolphins found in Sarasota Bay, FL over the course of two years. Of the 17, phthalates were detected in 12 individuals, or 71% of dolphins. The type of phthalates discovered was indicative of the source of the contaminant. With researchers detecting mono‐(2‐ethylhexyl) phthalate (MEHP) and monoethyl phthalate (MEP) most frequently. While MEHP is associated with plastic pollution, MEP is a breakdown product of diethyl phthalate (DEP), a compound that has been used in pesticide products as an inert ingredient.
“These chemicals can enter marine waters from urban runoff and agriculture or industrial emissions, but we also know that there is a lot of plastic pollution in the environment,” said Leslie Hart, PhD, lead author of the study to NOLA.com.
The detection results point to the need for increased concern considering the recent impacts on the dolphin population in the Gulf of Mexico. In 2010, the Deepwater Horizon oil spill killed between 30 and 70% of dolphins in the area, indicating it would take between 30 to 50 years for the population to recover. And as a result of the significant red tide events in Florida this summer, nearly 50 dolphins in southwest Florida died.
Studies of phthalate exposure in humans links the chemicals to endocrine disruption, reproductive effects, and liver and kidney toxicity. A study published in 2016 attributes phthalate exposure to 145,000 cases of endometriosis each year in the European Union, costing up to $1.4 million annually. A 2015 study also linked phthalate exposure to early menopause in U.S. women. While certain phthalates were removed from uses as an inert ingredient in pesticide formulations in 2016, there is no telling whether the inerts tested remain in agricultural chemicals used in the region. A similar biomonitoring study conducted in 2016 found the former undisclosed inert ingredients known as perfluroalkyl phosphinic acids (PFPIAs) in fish birds as well as dolphins tested in the exact same location.
Dr. Hart wrote in the study, “Although the sample sample size was small, this study provides some evidence that urinary levels of (phthalates) are relatively high in Sarasota Bay bottlenose dolphins based on comparisons to human urine … warranting more detailed study of exposure routes in the coastal marine environment.”
The researchers told NOLA.com that dolphins act as “great sentinels” for detecting broader issues with ocean habitats. “Any animals in the near-shore environment with similar prey are probably being exposed as well,” said Dr. Hart.
Ultimately, it is up to humans to reduce and eliminate the introduction of novel toxicants into marine waters. In addition to reducing plastic pollution, phthalates should be eliminated from pesticide formulations. Better yet are strategies, such as a shift to organic farming, which would eliminate the need for toxic pesticide use in the first place.
“We’ve introduced these chemicals – they are not natural toxins – and we have the ability to reverse it, to clean this up,” said Dr. Hart.
See past coverage for additional information inert ingredients in pesticide formulations. And visit Beyond Pesticides’ wildlife program page to learn more about the threats pesticides pose to ecosystems and what can be done to help.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.