A number of scientific papers have given rise to concern about a possible general reduction in male sperm counts and other reproductive disorders. These have resulted in a hypothesis that certain products in the environment which mimic the natural female hormone oestrogen may be the cause.
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. Phthalates are a large and diverse family of chemical substances with different hazard classifications regarding human health.
Further information and references may be found at http://www.plasticisers.org/science/health/endocrine-disruption
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)
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 Commission’s Scientific Committee on the Emerging and Newly Identified Health Risks (SCENIHR) stated in 2008 that, while “there is reason for some concern for prematurely born male neonates for which the DEHP exposure may be transiently above the dose inducing reproductive toxicity in animal studies, there is no conclusive scientific evidence that DEHP exposure via medical treatments has harmful effects in humans”.
The European plasticiser industry is 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.