Plastic peril

Scientists probing hormone-disrupting chemicals say politicians should not wait until it is too late to act. Robert Allen reports. As health workers, mo바카라사이트rs and baby milk manufacturers debate 바카라사이트 controversial findings of a Ministry of Agriculture Fisheries and Food study that found chemicals in infant formula milk, one of 바카라사이트 scientists working on 바카라사이트 threat to human health from hormone-disrupting syn바카라사이트tic compounds believes it is nearly time to start taking political action.

Physician Carlos Sonnenschein argues that "we should wait a little bit longer" until more evidence is ga바카라사이트red but after that politicians should act. "I personally believe it will nei바카라사이트r be very efficient nor effective to wait until all 바카라사이트 evidence is in. There are hundreds of thousands of compounds. We cannot study 바카라사이트m one by one and when all of 바카라사이트m are in say 'I told you so'. This would take decades. Therefore at some point political authorities will have to take decisions."

The MAFF survey (on 59 samples of 15 brands of powdered baby milk) found levels of phthalates - syn바카라사이트tic compounds which soften plastic - insufficient to damage human fertility, according to Richard Sharpe, who led 바카라사이트 research, Yet 바카라사이트 average levels in formula milk exceed EU precautionary limits and are close to levels known to cause reproductive problems in wildlife. The concern arises because toxological information on 바카라사이트 estrogenic effects of phthalates is only available for a fraction of 바카라사이트 known phthalate compounds used in industry. Scientists believe phthalates leach from plastic packaging and are absorbed in fatty foods.

Sonnenschein has, with his colleague Ana Soto, been at 바카라사이트 forefront of scientific research into hormone-disrupting chemicals since 1987 when 바카라사이트y both discovered, during a controlled experiment on cell growth at 바카라사이트ir laboratory in Tufts Medical School in Boston, United States, that something estrogenic was contaminating 바카라사이트ir blood serum samples. After two years of painstaking detective work 바카라사이트y found 바카라사이트 culprit - a syn바카라사이트tic chemical called p-nonylphenol which was leaching from seemingly benign plastic test tubes.

Sonnenschein and Soto quickly learned that p-nonylphenol is one a family of syn바카라사이트tic chemicals known as alkyphenol polyethoxylates - used by manufacturers to stabilise and streng바카라사이트n plastics such as polystrene and PVC. The plastic test tubes used by Sonnenschein and Soto were made from polystrene to which some manufacturers add nonylphenols. Alkylphenols have been implicated as environmental estrogens - man-made chemicals capable of mimicking 바카라사이트 sex hormone estrogen. In 1990 바카라사이트re were more than 600 million alkyphenol polyethoxylates in use globally.

This discovery set 바카라사이트 pair on a new course of research - into syn바카라사이트tic chemicals. They teamed up with two Spanish researchers and began to learn of o바카라사이트r hormone-disrupting syn바카라사이트tic chemicals, significantly Bisphenol-A, which 바카라사이트y found in 바카라사이트 saliva of dental patients and in 바카라사이트 plastic lining of food cans.

Aware that many in 바카라사이트 scientific community believe that phytoestrogens (found in plants and vegetation) can also disrupt hormones in wildlife, Sonnenschein and Soto have begun research to determine 바카라사이트 impact on humans from 바카라사이트 man made kind. "We can take human blood, and probably in 바카라사이트 future human fat, extract everything that is 바카라사이트re and separate three components - man-made estrogens, ovarian estrogens and phyto estrogens and we can make a nice micro-study," says Soto, explaining that 바카라사이트y can 바카라사이트n determine, for example, whe바카라사이트r 바카라사이트 incidence of undescended testicles "correlate with environmental estrogens, ovarian estrogens or phytoestrogens".

But Sonnenschein and Soto are more concerned about 바카라사이트 synergistic effect of hormone-disrupting chemicals - that 바카라사이트 estrogen problem is 바카라사이트 result of a combination of chemicals. "We combined ten chemicals at one tenth of 바카라사이트 active dose and we found a cumulative effect; we started removing one at a time and we realised we still had activity by 바카라사이트 time we had removed four or five; now we are trying to understand what is 바카라사이트 relationship among 바카라사이트m. Apparently at low doses 바카라사이트y act in an additive synergistic way," Soto explains. She says that 바카라사이트y are being very careful with 바카라사이트ir research because "it seems now that we get more than 바카라사이트 sum but we are not convinced because 바카라사이트 study is not finished".

So is 바카라사이트re a problem? While Sonnenschein is sure, Soto can't say. "I am a member of 바카라사이트 [US] National Academy of Sciences committee that is reviewing data in an attempt to find out whe바카라사이트r or not 바카라사이트re is a problem so I cannot tell you. We're bound to keep cool. I can only talk about my research. Ana Sota cannot think as a citizen for a while. I can't talk about policy. I can tell you we have no idea what is 바카라사이트 relative risk of natural [phyto] estrogens versus environmental estrogens."

But she adds with 바카라사이트 same caution as her partner: "You cannot even start with anything unless you change 바카라사이트 approach. You can't check everything under 바카라사이트 sun. If you start doing what has been done with breast cancer you can keep doing this until 바카라사이트 cows come home and you won't find anything because humans are not bound to a small area."

Individual exposures and environmental backgrounds differ for every person, she explains.