An Old Chemical Raises New Concerns

Short-chain paraffins, an obscure family of chemicals – important to the metalworking industry but virtually unknown to the public – is suddenly the subject of scrutiny from the U.S. Environmental Protection Agency. They persist in the environment, accumulate in human breast milk, can kill small aquatic creatures and travel to remote regions of the globe.

“We find SCCPs worldwide,” said Tala Henry, acting deputy director of the EPA’s National Program Chemicals Division. “We’ve found them in animals in the Arctic and we have measured them in human tissues in several places around the globe.”

Since their introduction in the 1930s, chlorinated paraffins have received little attention from U.S. authorities. But now the EPA, in an unprecedented move, has placed the compounds, known as SCCPs, on a short list of worrisome chemicals that the agency may regulate because of the risks they pose to wildlife and the environment. Their use and marketing are restricted in Europe, and Canada deems them toxic. Despite evidence of widespread exposure, few scientists are actively studying the prevalence, toxicity and ecological impact of SCCPs. In contrast, other chemicals that persist in the environment – such as DDT and dioxins – have received far more attention from researchers.

“There is minimal awareness of these compounds,” said Gregg Tomy, an environmental chemist at the University of Manitoba in Canada. “It’s certainly not a chemical that’s on people’s radar screens.”

Chlorinated paraffins are a complex group of manmade compounds, primarily used as coolants and lubricants in metal forming and cutting. They also are used as plasticizers and flame retardants in rubber, paints, adhesives, sealants and plastics. About 150 million pounds are used annually in the U.S. The family of chemicals is organized into short, medium and long-chain paraffins, based on the length of their carbon backbones. About 150 million pounds of chlorinated paraffins are used annually in the United States, according to the EPA, and China’s production of the chemicals has increased 30-fold in fewer than 20 years. Ohio-based Dover Chemical Corp., the sole manufacturer of SCCPs in the United States, did not respond to requests for an interview.

“We are pretty worried at the moment,” said Jacob Boer, head of the department of chemistry and biology of the Institute for Environmental Studies at the Vrije Universiteit (VU University) in Amsterdam. “The increase of chlorinated paraffin production in China is exponential.”

In an unprecedented use of the 1976 Toxic Control Substances Act, the EPA in December placed short-chain chlorinated paraffins on a list of four chemicals that may pose unreasonable risks to health and the environment. In its action plan, the EPA announced its intentions to investigate and manage those risks, possibly restricting or banning future use of SCCPs in the United States. It is the first time that the EPA has investigated the compounds, which are already regulated in Europe and under review in Canada.

Where have scientists found the chemicals?

• In the air, on land, in wastewater and in river and ocean sediments in North America, Asia, Europe and the Arctic.
• In food, including cow's milk and butter from Europe; and in grains, sugar, sweets and snacks, vegetables, fruit, fish and shellfish, meats, milk and other dairy products, like butter and margarine in Japan.
• In plastic and rubber products, where the chemicals are used as flame retardants and plasticizers.
• In the fat tissues of freshwater fish such as trout and carp in North America and Europe, marine mammals including Beluga whales, ringed seals and walruses in the Canadian Arctic, land animals including rabbit, moose and reindeer in Sweden, and birds and seabird eggs in the United Kingdom. (Certain SCCPs may biomagnify – meaning their concentration increases as they move through food chains, according to a 2008 field study on Lake Ontario trout.)
• In human livers, kidneys, fat tissue and breast milk.

“You find them pretty much wherever you go to look for them,” said Tomy, who found significant concentrations in sediments around the Great Lakes region.

But are they toxic? Here's what scientists have found:

• Small aquatic invertebrates: highly toxic to Daphnia, tiny aquatic crustaceans known as water fleas that are important food sources in lakes, streams and other ecosystems
• Fish: Less toxic, but chronic exposure to high levels is damaging to rainbow trout fed SCCPs in the lab.
• Birds: SCCPs can cause slight egg shell thinning in mallard ducks
• Mammals: SCCPs can cause cancer in laboratory rats and mice, specifically damaging the liver, thyroid and kidney. Otters have also shown liver damage from exposure. The effects on humans and other mammals is uncertain.

Originally published by www.environmentalhealthnews.org, where you can find the unedited version.

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