Softener hits humans harder


The widely held view that plastic softeners (plasticizers) do not pose a threat to human health is in for a rethink, warn German researchers.

BioMedNet News, 15. August 2003


BMN150803 - Plasticizers are ubiquitous because they make plastics flexible. Until now, experts thought they knew the extent to which these toxic chemicals are taken up in the human population, but now there are major concerns that uptake of one plasticizer, di(2-ethylhexyl)phthalate (DEHP), has been underestimated.

The European Chemicals Bureau (ECB) in Ispra, Italy, assesses the risk of chemicals to human health. It has just completed its final draft of the Risk Asssessment Report of Existing Chemicals. But now the German Bundesinstitut für Risikobewertung (BfR, Federal Institute for Risk Assessment) has made a request concerning the risk of one of the most used plasticizers worldwide: DEHP. There is an important observation to address, the BfR claim: humans seem to take in more DEHP than was previously estimated. The little request could have a massive impact on the chemical industry, should the fear be justified.

DEHP, the major representative of a chemical group called phthalates, is present in a wide range of plastic products, from wall coverings and waterproof clothing, to toys, cosmetics, car upholstery, food packaging, and medical devices. Until recently, it appeared that DEHP presented no risk to humans because absorption rates - through skin contact or inhalation - were deemed too low to effect health. More recently, however, animal studies have linked the toxin to carcinogenic, hormonal and, primarily, reproductive effects (especially in the testes). In some countries, including West Germany, phthalates like DEHP are forbidden in products that are used by very young children.

Critics say that this is not enough. For the ECB reassessment of the potential risk of DEHP, new risk-minimizing sanctions were only expected for children's products, but not for the general population. The BfR thinks that this should be reconsidered. This decision was taken following a study at the University of Erlangen, published earlier this year in the journals Environmental Research and Umweltmedizin in Forschung und Praxis. The study concluded that the general population is taking up much more DEHP than previously thought.

"Our study shows that the extent of DEHP exposure exceeds previously published estimations more than tenfold," said Jürgen Angerer, Chemist and one of the authors of the study that could rock chemical companies like the German firm BASF, one of the major producers of phthalates. Angerer and his colleagues Holger Koch, Bernd Rossbach and Hans Drexler applied a new method of measuring humans intake of DEHP.

"The problem until now was that correct assessments of intake were not possible because one wasneþt able to exclude contamination. DEHP is everywhere, in the lab itself," Angerer explained. And Holger Koch adds: "Its primary metabolite MEHP (the substance that is measured normally) is generated only in very low amounts of 5%, thus extrapolations derived from this low amounts multiplies the errors." The German team focused not on the monoester MEHP in probands urine, like researchers had in previous studies, but on secondary metabolites of DEHP, which were only generated by human metabolism.

The resulting values derived from the 85 peopleeþs urine in part considerably transgress the tolerable daily intake (TDI) determined by the EU Scientific Comittee for Toxicity, Ecotoxicity and Environment by 12%. The US Environmental Protection Agency´s (EPA) reference dose (RfD) is exceeded by 31%. "Health risks have to be taken into account," the authors conclude. The main source of DEHP in the human population seems to be food, they believe, because the intake through other means are known not to supply not such high concentrations.

"Although this is just a small study, we think this results should be taken into account in the EPCeþs risk assessment," said a spokesperson for BfR. Since previous studies of DEHP burden in food had found only low concentrations in adults, the EPC has not considered this aspect in its report. The German study now shows that it should.

"The BfR follows the precautionary principle." And, the spokesperson adds: "Iteþs good that the EPC just have the draft of its report, thus the results can be taken into account." Because 85 probands are too few for political decisions, the BfR recommend the setting up of larger studies to get a better pool. After that, researchers will need to evaluate the source of this DEHP.

Waiting for new results confirming the German study will take too long, say others, including Patricia Cameron of the conservation group BUND (Bund für Umwelt und Naturschutz), the German branch of Friends of the Earth. "Weeþre not in the situation for new studies. Iteþs time to act, to minimize the risk now," said the group's chemical expert. It is already known that DEHP is accumulating in breast milk, and some foods, including shrimps.

The fears are overblown, the chemical company BASF told BioMedNet News. "Probably no class of compound's influence on the physiological effects on humans and animals has been so well studied as the phthalates," according to company representative Jörg Hartmann. After twenty years of emotional debates and overwhelming amount of data "BASF is convinced that phthalates are no danger for humans and the environment."

But now evidence is emerging that humans take in much more DEHP than previously thought. "Meanwhile a US study conducted by the Center for Disease Control and Prevention (CDC) affirm our results," said German chemist Angerer.

And there is another point to consider. "Our study shows the intake of the general population," write the authors of the German study. "It has to be expected that the DEHP intake for certain subsets of the population, like premature infants, babies and adolescents, occupationally exposed workers and patients undergoing medical treatment like dialysis, transfusion or plasma donation, is considerably higher."

BioMedNet News, 15. August 2003

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