29 June 1998 00:00 [Source: ICB]The chemical industry is keeping its cards close to its chest regarding the endocrine disruption phenomenon and, as such, the public assume the industry is hiding something. Susannah Johnston looks for some answers.
In the public eye, the chemicals industry is guilty until proven innocent. Unfortunately, even volumes of 'sound' scientific evidence are often insufficient to back the industry's claims that a product is safe. So when the endocrine disruption issue came to the fore in the early 1990s, the industry knew it was in for a PR crisis.
Synthetic chemicals are held responsible for increased incidences of testicular and breast cancer, accelerated puberty in girls and other human fertility disorders. Despite industry, government and academic assurances that there is no proof of a causal link, the public remains sceptical.
But industry does not really help itself. Despite the fact that public fear about 'gender bending chemicals' has reached a critical point, the industry insists on using the word 'hypothesis' to describe the endocrine disruption phenomenon.
It is clearly no longer a hypothesis. There is enough evidence worldwide to conclude that certain chemicals have had hormone disrupting effects on wildlife. What is really in question is whether synthetic chemicals are to blame and whether human health is at risk.
Let us take two recent statements, the first by the US Chemical Manufacturers Association (CMA), the second by Greenpeace. The CMA maintains: 'Scientists have been aware of the hormone-like effects of chemicals and natural substances on birds and wildlife for a number of years. Only in recent years has the hypothesis been advanced that hormone-like compounds in the environment may affect human health.'
Greenpeace says: 'That exposure to synthetic endocrine disruptors can lead to adverse effects within wildlife populations is no longer in question. The potential for widespread impacts on human populations is also widely recognised. Some observed trends in human health could be mediated through effects on the endocrine systems.'
On the surface, the two positions appear similar. However, many sceptics are split over whether the 'suspicion' or 'potential' for human health effects warrants a precautionary approach.
At a recent conference in London entitled 'Hormone Disruptors in the Environment', delegates and speakers were united in their claim that there is insufficient evidence of endocrine disruption, both for humans and wildlife. Yet while this claim remains substantiated, we, the public, cannot be blamed for deducing that if polar bears - mammals like ourselves - can be affected by synthetic chemicals, then we can too.
According to Greenpeace: 'While further research is essential to our understanding, this alone is insufficient to ensure protection of human health. Precautionary action must be taken now to address those endocrine disruptors already identified.' Furthermore, it argues that evidence that a chemical binds to hormone receptors or influences hormone activity should be sufficient for that chemical to be targeted for substitution.
But since testing chemicals for hormone-mimicking potential is an expensive business, governments cannot do it without the help of industry and, despite considerable public pressure to do so, they are reluctant to legislate. In the meantime, the public remains ignorant and the information gap is filled by extremist views from environmental groups like Greenpeace or graphic media reports of emasculated alligators or hermaphrodite polar bears.
Another problem is that when industry presents its 'sound science' based on risk assessment, for example, the public is none the wiser. Risk assessments are incomprehensible to most people, and deeply confounding to risk assessors themselves. According to scientific consultants the Weinberg Group, what people understand are risks of one in a hundred or one in ten.
Inevitably, people focus on just the thing industry rejects - the intrinsic hazard of a chemical, eg carcinogenicity or reproductive toxicity, and ignore the exposure risk it poses.
Rightly or wrongly, the man in the street still believes he is not half the man he used to be. However, reproductive specialist Rob Weber of Erasmum University Hospital in the Netherlands told ECN that charting sperm count is a completely unreliable way of gauging male fertility. In fact, he said, sperm count is more likely to be affected by temperature, stress and other factors that by environmental oestrogens.
According to Katie Turner of the UK Centre for Reproductive Biology, who has been studying the impact of certain chemicals on male reproductive health, there is 'no direct evidence which implicates individual or groups of environmental oestrogens in the aetiology of any human disorder'.
Even the evidence on one of the most tested suspected human endocrine disruptors, bisphenol-A (BPA), commonly used in metal can linings, baby bottles and dental sealants, is inconclusive.
According to Wade Welshons of the Universtiy of Missouri-Columbia, despite its very low toxicity, BPA was 'unexpectedly high in the oestrogenic activity in animals' while 'foetal serum increases the oestrogenic effects a thousandfold'. However, he admitted it was still not clear how the animal evidence can be extrapolated to humans.
The unfortunate thing is oestrogenic effects are common for chemicals such as BPA which have phenolic hydroxyl molecules which happen to be 'the most useful group in chemistry'.
Industry is also, not surprisingly, keen to point out that the phytoeostrogens present in the average bowl of pea soup are fairly potent. About 300 plants are known to contain phytoestrogens, including whole cereal grains, seeds, soy, cabbage, beet, broccoli and peas.
According to CMA, a recent analysis of the normal diet concluded that the level of industrial oestrogenic compounds is 2.5 millionths of 1% of the daily intake of natural oestrogenic compounds (phytoestrogens) in foods. Consequently, it does not seem plausible that the small exposure to industrial compounds with hormonal activity could have any impact on public health, although research is continuing into this.
There is a danger, of course, that the public interest in endocrine disruption could mean the issue becomes too politicised. Legislators may feel that action should be seen to be taken and certain chemicals may be chosen as sacrificial lambs for phase-out or substitution, which is not an unlikely scenario. Indeed the UK Chemical Industries Association (CIA) feels that the lack of any causal links so far does not warrant preventative action.
###6672###A good example of this is the phthalate plasticiser debate raging in the European Union at the moment. European consumer affairs commissioner Emma Bonino advocates an emergency ban on the use of some phthalate-containing toys designed to be put in the mouth. Many industry sources find it hard to believe that scientific objectivity is not lost when an issue moves into the realms of consumer protection politics.
According to Reinhard Laenge of the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) task force on environmental oestrogens, conclusions from recent workshops and conferences 'have clearly stated the need for the development of a testing strategy to analyse the potential of chemicals to affect reproduction and development of wildlife species due to endocrine disruption'.
The public imagination was captured more recently in the UK when the Environment Agency for England and Wales (EA) published the alarming findings of research it had commissioned into oestrogenic effects on fish in UK rivers. It showed there was significant oestrogenic contamination detected in most estuaries surveyed in 1997. Intersex flounder were found in the Mersey and Tyne estuaries in northern England, some of which had fully developed eggs in their testes.
The findings were published along with an EA consultation document Endocrine-disrupting substances in the environment: What should be done? According to the EA's Geoff Brighty, 'There is no question that the agency is concerned.' What he was not sure about was what powers it had to protect the environment. He admitted that the agency was not looking for a problem, and that one of the major drivers in its actions so far had been public perception.
How does the agency make risk assessments when the weaknesses in its data sets are so apparent. For example, there are not enough in vivo test results and insufficient evidence of how different substances interact.
However, the UK Chemical Industries Association (CIA) said it could not support the regulatory action proposed by the agency. It stated: 'There must be more than a simple suspicion of an effect to argue for a ban or substitution of a chemical.'
It also uses its favourite argument against substitution - the danger that one chemical, for which data and risk assessment are available, might be 'replaced by a chemical on which data is poor, and which might turn out to be less benign'.
According to environmental group Friends of the Earth, the CIA makes the mistake of suggesting that, while opposing actions by regulators to control products, it nevertheless believes that 'a customer-led precautionary approach helps significantly towards ensuring that any suspected problems are controlled through market mechanisms along the supply chain'.
To this end, the public could be forgiven for thinking it may have to arm itself with enough epidemiological and toxicological knowledge to make its own informed decisions on whether to buy or boycott a product.
Friends of the Earth also criticised the agency for focusing too much on the potential effects of man-made chemicals on the health of fish in UK rivers. 'The available research evidence suggests that these effects are more likely to be due to the discharge of naturally-occuring oestrogens in domestic sewage than to industrial pollution.'
The endocrine disruption phenomenon is a 'Catch-22 situation' for industry. More in vivo evidence is required on a priority list of substances before fully defensible regulations can be introduced. This is going to be an expensive and time-consuming business, so the US, Japan and the EU are cooperating on the issue to prevent duplication of research.
Cefic's in-house research team on the issue, the Endocrine Modulators Steering Group (EMSG), was set up in 1996 so that 'the European chemicals industry can take an active and responsible role in understanding the issue. Its recently launched $7m research campaign covers environmental/wildlife, human health and finding a testing strategy and risk assessement model.
And if $7m appears to be a drop in the ocean compared with the size of the potential problem, Rob Taalman, chairman of the EMSG, told ECN that work on individual sectors of the industry on the effects of individual chemicals, such as alkylphenol/ethoxylates, phthalates and Bisphenol-A, will continue.
The EMSG is collaborating with the World Health Organisation (WHO), the Organisation for Economic Cooperation and Development (OECD), scientific bodies, universities and interest groups. Results of the research will be published in peer-reviewed journals and will, no doubt, be eagerly awaited.
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