Perfluorochemicals in polar bears, arctic foxes, ringed seals, mink, birds, and fish collected in the Arctic

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http://pubs.acs.org//journals/esthag-w/2003/nov/science/rr_piece.html

 

 

Science News - November 26, 2003

 

Another piece in the perfluorinated puzzle

 

Canadian scientists have found an important group of long-chain

perfluorochemicals in polar bears, arctic foxes, ringed seals, mink, birds, and

fish collected in the Arctic. Their research, which was posted to ES & T’s

Research ASAP website this week (10.1021/es034727+), marks the first effort to

track the environmental occurrence of long-chain perfluoroalkyl carboxylates

(PFCAs) and indicates that they are likely to be widespread at low

concentrations throughout the environment, according to the authors.

 

The presence of PFCAs in the Arctic offers an important clue to why

perfluorinated chemicals have become ubiquitous in the environment, says

coauthor Scott Mabury, a University of Toronto chemist. Persistent

perfluorinated compounds have presented a puzzle to scientists, environmental

groups, and regulators since the recent unexpected discovery of perfluorooctane

sulfonate (PFOS) in animals and humans worldwide. The highest concentrations

measured in animals were only about a tenth lower than toxicity test

concentrations that caused adverse effects in lab animals. These findings led

manufacturer 3M to voluntarily announce in 2000 a manufacturing phaseout of

perfluorinated chemicals, despite the lack of a satisfactory explanation for how

these compounds are spreading.

 

The new ES & T paper will also help determine the overall hazard posed by body

burdens of perfluorinated compounds, because some PFCAs—particularly

perfluorooctanoic and perfluorodecanoic acids—are thought to have a similar

mechanism of toxic action to PFOS, which adds to the potential overall toxic

effect of perfluorinated chemicals, say the authors.

 

PFCAs are fully fluorinated carbon molecules with a carboxylate group on the

end. The best known member of this class is perfluorooctanoate (PFOA), a

perfluorinated surfactant that has widespread applications in chemical

manufacturing, aircraft production processes, and some electronic products. The

U.S. EPA is now investigating PFOA because of concerns over the compound’s long

residence time in humans and the possibility that at its current concentration

in mothers’ blood it may pose developmental risks to children (Eniviron. Sci.

Technol. 2003, 37, 201A).

 

Although there are no PFCA sources in the Arctic and the carboxylates are too

nonvolatile to undergo long-range transport, Mabury, Jonathan Martin (also of

the University of Toronto), and colleagues looked for long-chain PFCAs because

they hypothesized that such compounds are the likely breakdown products of more

volatile precursors (telomer alcohols). EPA has been conducting public meetings

since April to negotiate binding consent agreements with manufacturers of

telomer alcohols, which are precursors for chemicals used as surfactants and

stain protectors, in an effort to obtain monitoring data that could lead to

sources.

 

“We’ve found telomer alcohols in the atmosphere, and we’ve shown that the

alcohols persist long enough to make it to the Arctic,” says Mabury, referring

to research published in September (Environ. Sci. Technol. 2003, 37, 312A).

“We’ve hypothesized that PFCAs are among the breakdown products, and we’ve found

them—although we haven’t yet proved the link,” he says.

 

The Canadian scientists found low (nanogram-per-gram) levels of PFCAs with

molecules containing 9–15 carbon atoms in samples of many different Arctic

animals that were collected by subsistence hunters and trappers. Total PFCA

concentrations were about 3–20-fold lower than total PFOS concentrations for all

animals except mink. Mammals feeding at higher trophic levels had greater

concentrations of PFCAs than did those at lower positions.

 

“The information about carboxylic acids provides a new avenue to explore the

sources of these compounds to the Arctic,” says toxicologist Kannan

Kurunthachalam at the University of New York, Albany. —REBECCA RENNER

 

 

 

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