Chemicals keep falling on our head
PFOS is better known for being used to make non-stick pans, grease proof pizza boxes and (ironically) rain-proof coats.
11.05.2005 |Sascha Gabizon
Scientists have discovered that rainwater falling on the city of Winnipeg in Central Canada is contaminated by the "non-stick" chemical PFOS (perfluorooctane sulphonate) as well as other chemicals (called PFCAs, or perfluorocarboxylic acids) belonging to the group of "perfluorinated" chemicals.
According to research from the local Department of Fisheries, perfluorooactane sulfonate (PFOS) was found in rainwater at concentrations of 0.59ng to the litre.
PFOS and PFCAs have a myriad of uses in consumer and industrial products, where they are used as refrigerants, agrochemicals, chemical catalysts and surfactants. PFOS is better known for being used to make non-stick pans, grease proof pizza boxes and (ironically) rain-proof coats. They are stable and do not break down easily in the > environment.
Unfortunately, it is the same qualities that make then attractive for consumer use, that make them potentially harmful for people and wildlife. Their chemical stability means that they are gradually building up in the atmosphere and in the environment.
As Dr Gregg Tomy, from the Freshwater Institute and the University of Manitoba, who carried out the research, explained, "PFOS is pretty resistant to degradation and may persist even after treatment at our local water treatment plants". Obviously, this could mean that the city's drinking water is also polluted with PFOS.
So just how harmful is PFOS? According to the OECD's assessment of its hazards, it is 'persistent, bioaccumulative and toxic to mammals. It has a half-life of 100 days in rats, 200 days in monkeys, and years in humans'. In monkeys it has been found to cause liver damage, pancreatic damage, lung damage, decreased thyroid hormone levels and,in some cases, death.
Rainwater polluted in Europe
Unfortunately, this is not the only evidence of harmful chemicals finding their way in rainwater. In Europe, TNO, the Dutch research establishment analysed samples of rainwater taken from 50 different sites in Belgium, Germany and the Netherlands.
The highest concentrations of chemicals TNO found in the rainwater were phthalate plasticisers - at one location there were concentrations of up to 100,000 nanogrammes per litre (ng/l). Another chemical, bisphenol-A was found in rainwater collected at one site in concentrations of up to 352 ng/l. Both these chemicals are endocrine disruptors * known to be able to interfere with the body's reproductive functions.
The chemical alkylphenol was found in rainwater from almost all locations. At one collection point it was concentrated as high as 924 ng/l, which is almost three times the safety level in freshwater set by an EU risk assessment for one type of alkylphenol called nonylphenol (330ng/l).
Contamination * will go far
Neither the research in Winnipeg, nor at the sites in Europe found any obvious source of the chemicals. The presence of chemicals was so widespread in the European study that the contamination levels seem to reflect background levels in the atmosphere.
Worldwide, recent measurements in the troposphere (the atmosphere just above the earth's surface where most of the 'weather' originates) demonstrate that chemicals are escaping from the products in which they were incorporated, travelling huge distances, and are then precipitated from the atmosphere by oxidation and falling as rain.
This point was also made by Mark Loewen, from the Freshwater Institute and University of Manitoba, who worked on the Winnipeg study. "It wasn't possible to pinpoint any specific source of pollution - both local and remote sources could very well be contributing to the presence of these compounds in the atmosphere, " he said.
As Joan Baez and Marianne Faithfull once sang "What have they done to the rain?"
For more information:
Julian Scola, Communications Manager
WWF DetoX Campaign
Tel: +32 2 743 8806
E-Mail: jscola@wwfepo.org
