The study that has just been accepted by the Environmental Science and Technology journal, raises new questions about the use of triclosan which the scientists say has potential toxic effects in the environment when exposed to sunlight.
The antibacterial agent found in many hand soaps, deodorants and other consumer products was patented in 1964 and introduced into the market in the early 1970s. Since then, lobby groups have claimed that scientific studies link the chemical to endocrine system disruption, cancer and increased dermal sensitisation.
Professor Arnold’s group and researchers at Pace Analytical Services in Minneapolis studied the sediment of eight lakes throughout Minnesota with varying amounts of treated wastewater input, gathering sediment cores one meter from each of the lakes by using high tech methods to analyze the chemicals contained in the sediments over time.
As a result, the team found that sediment collected from large lakes with many wastewater sources had increased concentrations of triclosan, chlorinated triclosan derivatives, and triclosan-derived dioxins since the patent of triclosan in 1964.
"Some sediment segments dated back more than 100 years."
In small-scale lakes with a single wastewater source, the trends were directly attributed to increased triclosan use, local improvements in treatment, and changes in wastewater disinfection since the 1960s.
“When UV disinfection technology replaced chlorine in one of the wastewater treatment plants, the presence of chlorinated triclosan derivatives in the sediments decreased.”
In the lake with no wastewater input, no triclosan or chlorinated triclosan derivatives were detected. Overall, concentrations of triclosan, chlorinated triclosan derivatives, and their dioxins were higher in small lakes, reflecting a greater degree of wastewater impact.
"The results were similar to other recent studies worldwide, but this was the first broad study that looked at several different lakes with various wastewater treatment inputs," Arnold explains.
"While wastewater treatment removes the vast majority of triclosan, these systems were not designed with this in mind. We need to continue to explore all aspects of this issue," he adds.
FDA stance on triclosan
Beyond its use in toothpaste to prevent gingivitis, the U.S. Food and Drug Administration has found no evidence that triclosan in antibacterial soaps and body washes provide any benefit over washing with regular soap and water and the Administration and the Environmental Protection Agency continue to study the effects of triclosan on animal and environmental health.