Hypothesis on endocrine disruption and other health issues

This has become known as the hormone - or endocrine - disruption theory. However, there is no study based on sound science that shows this actually occurs.

Extensive research is being carried out by the chemical industry and others in Europe, the United States and elsewhere, into endocrine disruption theory. Phthalates have been implicated as one of a number of possible hormone-mimicking chemicals but they are not the only substances under scrutiny. So far, over 80 man-made products have come under scrutiny along with many naturally occurring substances (phyto-oestrogens) found in plants and vegetables. Concerns have been raised about a possible endocrine effect of some phthalates, although the most recent studies, which include in-vitro and in-vivo tests on DEHP have shown that there is no reason that the suspected phthalates would produce oestrogenic effects in humans. It is, therefore, very unlikely that any significant risk to human reproductive health is associated with phthalate use. However, they continue to be rigorously researched and scientifically assessed to confirm they are safe to use and pose no threat to health or the environment. Such assessments have been undertaken on five phthalates (DBP, DEHP, DINP, DIDP and BBP) under the EU's Risk Assessment Procedure (Council Regulation [EEC] 793/93).

While the International Agency for Research on Cancer (IARC), part of WHO, used to classified DEHP as "an agent possibly carcinogenic to humans", this was based only on rodent studies and did not take into account more recent understanding of the underlying mechanisms. It has now changed its classification of DEHP to "not classifiable as a human carcinogen" based on existing scientific evidence that supports the safety of DEHP as a component of PVC medical products. In addition the Specialised Experts Working Group of the European Commission has concluded that there is no evidence to warrant the classification of DEHP as a carcinogen. (Opinion of the Scientific Committee on Medicinal Products and Medical Devices issued on 26 September 2002)

Recently three independent panels convened by Baxter Healthcare Corporation confirmed that DEHP does not pose a human cancer risk. With regard to cancer, it is important to note that since 1980 a large number of investigations have shown that feeding high levels of phthalates to rodents over their lifetime causes a large increase in microbodies in the liver called peroxisomes. This 'peroxisome proliferation' leads to the formation of liver tumours. However, when these chemicals are given to non-rodent species such as marmosets and monkeys (primates considered to be metabolically closer to humans), such liver peroxisome proliferation and liver damage is not seen. The changes seen in rats are therefore likely to be a species-specific effect. The European plasticiser industry (represented by the European Council for Plasticisers and Intermediates - ECPI) is conscious of the genuine public concern which now exists around the use of phthalates and takes this very seriously. The industry is in favour of a public debate, and considers that it has a duty to respond to public concern by ensuring that there is an open exchange of information about the performance of its products. Clearly, if there were evidence that any single product presented a serious health risk, the plasticiser industry would have no hesitation in withdrawing it. The industry is also committed to supporting and, where appropriate, commissioning further scientific research to make sure that the current use of phthalates poses no hazard to the health of people or the environment.