Antibacterial found in dolphins.

Jun 18, 2009

Fair, PA, H-B Lee, JAdams, C Darling, G Pacepavicius, M Alaee, GD Bossart, N Henry and D Muir. 2009. Occurrence of triclosan in plasma of wild Atlantic bottlenose dolphins (Tursiops truncatus) and in their environment. Environmental Pollution doi:10.1016/j.envpol.2009.04.002.

Synopsis by Karen Kidd

For the first time, the popular antibacterial agent triclosan is found in the blood of a marine mammal.

A bacteria-killing chemical widely used in an array of consumer products has made its way down kitchen and bathroom sinks and into dolphins living in US coastal waters.

Researchers report for the first time that a marine mammal – the bottlenose dolphin – is accumulating triclosan from water bodies where treated sewage is released. The study examined animals from rivers, an estuary, a harbor and a lagoon in South Carolina and Florida.

Triclosan is a common additive in soaps, deodorants, toothpastes and other personal care products that is included to help control bacteria and their related illnesses.  It is also put into consumer products like socks, cutting boards and garbage bags to curb the growth of bacteria.

The antibacterial enters wastewater mainly from home sinks. Even though most (up to 95 perent) of it is removed when these waters are treated, it is one of the most commonly found contaminants in rivers and estuaries downstream of treated water outfalls. 

Triclosan can persist in waterways, affect natural communities of bacteria and algae, and also concentrate in fish and other aquatic organisms. It has also been found in the urine, breast milk and blood of humans.

Bottlenose dolphins live in temperate and tropical waters. They are the most abundant dolphin species along the eastern coast of the United States. They are often seen in harbors and estuaries, including in heavily populated areas.

In this study, wild bottlenose dolphins were live captured from several sites within an estuary in Charleston, South Carolina and in the Indian River Lagoon, Florida in 2005. Blood samples were taken from 13 animals from each area and analyzed for triclosan.

The antibacterial agent was detected in 31 and 23 percent of the animals from the two sites, respectively, at levels ranging from 0.025 to 0.27 parts per billion. These levels are similar to what has been measured in the blood of humans.

It is well known that marine mammals are contaminated with conventional persistent organic pollutants like PCBs. This new study shows bottlenose dolphins living in densely populated areas are becoming contaminated with a chemical found in personal care products.

What is not known is how widespread the contamination is and how it may affect the animals' health. The researchers suggest further studies are needed to understand interactions and effects "related to triclosan in the environment, its potential transformation into other toxic compounds and possible interference with hormone systems that can alter biological systems even at extremely low levels."