A chemical formerly used in pesticides and most recently in carpet-cleaning products has been ingested by wildlife throughout North America, according to a study appearing today in the journal Environmental Science & Technology.
The blood of dolphins, fish and birds all tested positive for perfluoroalkyl phosphonic acids, one class of a common industrial chemical group used for a variety of purposes, including stain-resistant carpet sprays and nonstick cooking surfaces since the 1950s.
Perfluoroalkyl phosphonic acids in particular were used in several pesticide formulations in North America and some countries in Europe since the 1970s, according to Zhanyun Wang, a scientist at the Institute for Chemical and Bioengineering in Zurich. Wang has done extensive research on these chemicals but was not involved in the current study.
“There is no new information to show if they are increasingly or decreasingly used,” Wang said, adding that any information about current use of these chemicals is sketchy at best. “More information from the manufacturers is needed.”
Reports from the Environmental Protection Agency suggest that highest production of perfluoroalkyl phosphonic acids in the United States — somewhere within the range of 4.5 and 227 tons — occurred between 1998 and 2002.
Beginning in 2006, the EPA restricted the use of these chemicals in pesticides, and currently, there are no perfluoroalkyl substances approved for use as inert ingredients in pesticide formulations. In a published report, the agency noted that it had “identified human health and environmental risks of concern.”
Yet environmental scientists believe perfluoroalkyl phosphonic acids continue to be used today in commercial products, including rug-cleaning formulas.
Recently, Amila O. De Silva, a scientist who works for the Canadian government, conducted a small-scale experiment. She and her colleagues tested 102 residential dust samples in Vancouver between 2007 and 2008. They detected perfluoroalkyl phosphonic acids in 83% of the household dust samples.
De Silva then decided to take a look at the wider environment.
“We wanted to do a survey of these relatively under-studied compounds in aquatic organisms,” De Silva said of her new study, which was funded by the Canadian government. She and her colleagues analyzed blood samples from one type of fish, one type of bird and one type of mammal across North America: northern pike found near the Island of Montreal; cormorants from the Great Lakes; and bottlenose dolphins from both Sarasota Bay, Florida, and Charleston, South Carolina.
“We aimed for diversity: air-breathing versus water-breathing, differences in habitat, different taxonomic groups,” De Silva said.
Testing the blood of these different species occupying separate environmental niches, De Silva discovered that concentrations of perfluoroalkyl phosphonic acids were low.
However, she and her team detected these chemicals in all of the samples from fish, birds and mammals — 100%.
Perfluoroalkyl phosphonic acids are known to linger in the environment because sunlight, water and microbes are unable to break down these complex chemicals into smaller harmless chemical components.
All the mechanisms the environment has to clean itself up “don’t seem to apply” to them, explained De Silva. This long life means both people and animals are more likely to inhale or ingest them.
“Previous work by other scientists in three separate publications have shown perfluoroalkyl phosphonic acids are found in human blood samples from North America and Germany,” De Silva said. In Germany, for example, scientists found the chemical in human blood from as far back as 1983 and annually up until the most recent tested sample in 2009, she said.
Yet no published studies on the toxicity/effects in humans or any other organisms exist, as far as De Silva knows. “The EPA is leading some laboratory studies on perfluoroalkyl phosphonic acids in mice, and our colleagues at the University of Toronto are working with perfluoroalkyl phosphonic acids in rats,” De Silva said.
Surprisingly, even though the United States restricts use of these compounds, Canada permits them, said De Silva. “That has implications when we look at the Great Lakes, which are binational.”