Bisphenol A: Sense and Sensationalism

Related tags Bisphenol a

Bisphenol A is in fact one of the world’s most researched chemicals and has a history of risk assessment in Europe going back a quarter of a century. So why is it still generating such heated responses? asks Sebastian Day

It has been said that it is possible to generate a ‘scare’ story about anything – even water. But somehow it is far easier for the press to grab the reader’s attention (as yet another hack is attempting to do here) when the substance in question is an endocrine disruptor.

Science tells us that bisphenol A (BPA) is just that. In other words, like some other chemicals, it mimics the hormone oestrogen. It is used as a starter chemical in the production of polycarbonate and synthetic resins, such as the epoxy resins used in can and metal closure coatings. It has been detected in a wide range of domestic consumer goods and – most notoriously – baby feeding bottles.

But science also tells us that safe levels, or tolerable daily intakes (TDIs), can be set. These are the result of decades of research into the chemical. Not all of that research has confirmed those safe levels, but then part of the risk assessment challenge has been gauging the relative value of the various published studies.

Diane Benford, head of chemical risk assessment at the Food Standards Agency (FSA), explains:
“There’s a lot of information around that supports the TDI set by the EU back in 1986. Other studies have raised concerns, some of them relating to low doses of BPA. But subsequent attempts to reproduce those low-dose pieces of research have failed.”

In fact, verifiable research carried out up to 2006 seemed to point in the opposite direction. “The TDI was lowered in 2002 due to the uncertainty about effects at lower doses, but then increased back to the 1986 level in 2006, since new studies appeared to reduce the concerns regarding BPA,” says Benford.

Arguments abound

Critics might say that, if it is relatively easy to generate a ‘scare’, it is equally easy to discredit inconvenient studies. In fact – predictably - both ‘sides’ are quick to point out flaws where it suits them. But there do appear to be valid concerns regarding some of the studies to have highlighted risks associated with BPA.

“For example, if you conduct studies where BPA is injected directly, that is very different from the way it would normally be ingested,” says Benford. “Quite a lot of studies have taken this approach. It’s valid if you can compare the results directly with ingested BPA. But the danger is that you’re not comparing like with like.” As she explains, when ingested, BPA rapidly assumes a non-oestrogenic, non-active form.

Increased heat has been generated around BPA over recent months, prompting a major EU reappraisal by the European Food Safety Authority (EFSA). This intensification is largely the result of new regulatory moves in Canada, Denmark and France. Many would say that, in the meantime, research has raised little or nothing in the way of new concerns about BPA.

So why the new restrictions?

In Canada, this has taken the form of a ban on polycarbonate baby bottles. In Denmark, a temporary ban (which in the longer term will be subject to European Commission approval) affects BPA-containing bottles and coated metal packaging destined for children of three years and below.

Many would say that these measures have come about despite the science rather than because of it. Jasmin Bird, communications manager at industry association PlasticsEurope, cites one example: “There was a risk assessment by the Health Canada authority, which concluded that typical exposure was extremely low and posed no risk to the population. Despite that, the minister responsible decided to impose restrictions.”

David Smith, technical manager at the Metal Packaging Manufacturers’ Association (MPMA), makes a similar point about the recently-completed ‘Stump’ study on developmental and neurotoxological effects. “It indicates to most reviewers no negative effects at relevant dosage levels,” he says. “Nonetheless, it has been cited in Denmark’s justification of its precautionary ban.”

At the British Plastics Federation (BPF), public and industrial affairs director Philip Law sums up these recent moves: “The current debate about BPA has become politicised and detached from scientific reality.”

Precautionary principle

Part of this detachment has come thanks to the so-called ‘precautionary principle’. But as the MPMA’s Smith says: “This is a misuse of the term, if industry then has to turn to potentially less safe, less well-evaluated alternative materials. This is an aspect normally ignored by pressure groups.”

After its own assessment, the Swiss health authority highlighted this problem, warning that “a well-characterised risk would be replaced with a conspicuously unpredictable risk”.

Nick Kernoghan, director of testing at Pira International, takes this logic a step further. “The real danger to public health would be from poor quality metal closures which didn’t preserve the food inside them, exposing people to potential food poisoning. That could happen if you didn’t have the right coating.”

In fact, in a blog, FSA chief scientist Andrew Wadge has compared the “disproportionate alarm over potential hazards” in the case of BPA with the “real risks” of harmful bacteria such as campylobacter.

Returning to the topic of alternative can and closure coatings, Smith at the MPMA says: “It takes a good five years from start to finish to develop, pack test and upscale production of a new lacquer system. The Danish action gave industry just three months to change – a ludicrously short time.” Fortunately, he adds, the industry had already been evaluating alternatives, though only for around two years.

There are other questionable aspects to the overused, and sometimes abused, ‘precautionary principle’. As Bird at PlasticsEurope puts it: “It’s a catchy phrase and an important concept, which everybody will support. In fact it’s already built into the standard safety assessment procedures when setting, for instance, TDIs in Europe.”

As the FSA points out, when setting the TDI, it is assumed that the average human could be 10 times more sensitive to the effects of BPA than the animals used in research. It is further assumed that the most sensitive humans are 10 times more susceptible than this average, resulting in a safety factor of 100.

Bird continues: “Invoking the ‘precautionary principle’ implies that there are gaps in the data. But given the extensive database on BPA, this is certainly not the case.”

The BPF’s Law comes at the subject from another angle. “The problem with invoking the ‘precautionary principle’ is that all branches of human activity carry risk and every material in use carries the potential to be criticised,” he argues. “Where do you draw the line before the ‘precautionary principle’ becomes a recipe for anarchy in our regulatory systems?”

Zero-risk trend

Given the number of people who die falling down stairs, Pira’s Kernoghan suggests not-too-seriously, the same principle could be used to justify a ban on staircases and enforced bungalow-living for all.

Picking up on this idea, Bird points out: “Overall, there’s a trend towards ‘zero risk’, the sense that as technology advances it must be possible to have a clearer idea: is there a risk or not? In this challenging situation, who do you trust? Do you trust the assessment of someone who is an expert authority – or someone who isn’t?”

Moving away from wider philosophical questions about the elimination of risk, there is an important issue here about the types of studies that are carried out, who carries them out, and who funds them.

Campaign groups like to contrast the large numbers of studies which have raised concerns about BPA with the smaller numbers – many funded by industry – which have not. This overlooks the fact that many of those studies sponsored by industry and governments have been much larger in terms of scope and sample size.

As Kernoghan at Pira says: “Toxicology in animals is an incredibly expensive business. Studies not conducted by industry or governments have to be made cheaper, and one way is to use fewer animals. Here, you can get into an interesting debate about statistics.” That debate might include the idea that larger samples are understood often to yield more representative results.

There are other issues undermining the argument that industry should not be involved in research for reasons of ethics or objectivity. Says Bird at PlasticsEurope: “Everyone from business to non-governmental organisations and individual scientists have their particular interests in research. Industry’s interest has to be in the safety of a product, otherwise it won’t be there tomorrow.”

The FSA’s Benford makes a similar point about government agencies: “The FSA was set up with the specific aim of protecting people’s health. It simply wouldn’t be in our interest to ignore evidence that our scientists believed showed that the health of babies – or any other part of the population – was being put at risk.”

Regarding industry, Bird adds: “The REACH regulations in Europe require industry to provide the data that enables authorities to assess a substance. So the reproach, so often heard, that industry is funding all the larger-scale research is groundless. It’s what the regulatory system requires.”

The waves created by the BPA debate travel a long way. They take in definitions about how existing rules should be implemented, but also safeguards for the independence and influence of evidence-based science, and the responsibilities of public health authorities – and, not least, the media – in the face of that science.

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