OPINION: Where are the independent voices that can bring reason
to the debate about Bisphenol A? Richard Moore details the canmaking industry’s position
In the current heated public debate on Bisphenol A (BPA), it is striking that nearly every press and television item has aligned with the conventional wisdom that the BPA in can coatings is a harmful chemical, responsible for obesity, breast cancer, hyper activity in children, reduced sperm count, and a dozen other ‘modern’ illnesses.
In reality the media are relying entirely on the views of a small but vocal group of activists using controversial research methods. Properly conducted science-based studies showing no adverse effect have been consistently ignored. In the absence of any kind of balanced view, let me use this venerable column to give the other side of the story:
● The coatings used to prevent corrosion on the inside of cans are very thin, equivalent to that of printing inks on paper (about three microns).
● Approximately 80 percent of all can coatings today are based on epoxy resins, which contain a very small proportion of BPA (less than 0.1 percent).
● External studies show that migration from the coating into the product varies, but is usually around 25 parts per billion, and rarely exceeds 200 parts per billion. 25 parts per billion may sound a lot, but it is the equivalent of a teaspoon in an average swimming pool (5 millilitres in 200,000 litres).
● The current tolerable daily intake in Europe of 0.05 mg/kg of body weight, as defined by the European Food Standards Authority (EFSA) in 2009, would justify a migration limit of 3,000 parts per billion, after allowance for a safety factor of 100.
● There are many other common sources of BPA in everyday life, including newspaper print and cash till receipts. Although easily transferred to fingers and therefore ingested, they do not receive the same journalistic concern (‘Reading Newspapers Can Reduce your Sperm Count’ is a headline we are not likely to see).
● Many of the adverse health effects cited by the anti-BPA lobby are based on injecting BPA into the blood stream of rats and mice. However, humans are exposed to BPA through ingestion. The chemical is rapidly broken down first in the gut and then in the liver by enzymes, transforming it into a water soluble BPA-glucuronide. Being water soluble, this is easily excreted in urine. This happens very quickly. The half life of BPA-glucuronide is six hours. In adult human volunteer studies, no BPA is found in blood.
● Tests have shown that young children – and even premature babies – are able to transform and excrete BPA in much the same way as adults.
● Since the 1930s scientists have known that BPA has hormone-like properties. But its impact is very limited: compared to the most common oestrogen (the one used in the contraceptive pill) it is 10,000 times less potent. Furthermore, once BPA is broken down and becomes BPA-glucuronide, it loses its hormonal properties.
● Nearly all of the studies on BPA have relied on laboratory tests on rats. Although we share much of their DNA (and possibly some of their character traits), rats are not humans. Other studies show that rodents are more sensitive to oestrogens than humans, and that humans metabolize and excrete BPA from their system far more quickly than rats and mice.
So we have a very small amount of a very small quantity of a substance which has a weak hormonal impact (which in any case disappears after digestion), tested in conditions which do not accurately replicate their impact on humans, and no evidence of actuarial or measurable risks – the odds, in other words, of someone, somewhere getting sick – but hypothetical risks, scaled up from laboratory studies. On this slim platform the anti-BPA lobby rests its case.
But the scientific evidence does not support the hypothesis. The ‘200 clinical studies’ often cited by anti-BPA activists have been selected amongst many others that show no adverse effect. Importantly they are often based on small samples with questionable protocols, and on injection of BPA into the blood rather than feeding. The normal test of a scientific hypothesis is that it be reproducible. But none of the small-scale tests have been corroborated by larger sample studies carried out under Good Laboratory Practice (GLP).
For instance, a recent review by the German Institute of Risk Assessment (BfR) of a 2010 study conducted under GLP, found that there was no evidence of adverse hormonal effects in rats from consuming various levels of BPA in their diet, and no evidence of any ‘low-dose’ effect. In common with numerous previous GLP studies showing no effect, this report went unnoticed by the media.
No doubt for this reason, and despite strong political and media pressure, none of the world’s leading health authorities (FDA in the US, EFSA in Europe, AIST in Japan) have banned the use of BPA in baby bottles or can linings, since to do so would be to fly in the face of the scientific evidence. The most they can do is to acknowledge ‘public concern’ and advise a switch to alternatives, as the FDA felt obliged to do in its latest pronouncement (January 2010).
Contrary to what some journalists believe, BPA does not threaten the existence of [the canmaking] industry. We can and in many cases have already developed potential alternatives, and if our customers conclude that the media pressure is too great, we will change. But it will need time (in some cases years, not months), to be completely sure that the alternatives are as safe and as robust as the proven epoxy-based lacquers we use today. The immediate replacement of BPA that activists and some journalists are screaming for would lead to a totally unacceptable risk to public health, and a real transgression of the principle of precaution. And replacement will also come at a cost. Leaving aside the $50 million already spent on studies, and the cost of shelf-life and food safety testing, the increased material cost will be more than $100 million per annum for the industry, just in North America and Europe.
Have we really become so risk-averse that we would knowingly spend this much to remove a risk that is so uncertain, and so unquantifiable? How much should society spend to remove an irrational fear created by unquestioning journalists and bad science? I can think of several better uses for the money, many of which have a more certain return. A donation of the same amount to the Save the Children fund, for instance, would finance 2,400 fresh water wells for villages in Africa, or provide 1.4 million nutrition packs for malnourished children.
Are there really no independent voices speaking out against this madness? Well, actually, there is one. It’s not a journalist, but a non-profit university website called STATS (http://www.stats.org), devoted to accurate reporting of statistics by the media. Of the reporting on BPA, Trevor Butterworth wrote:
“Scientists, regulators, and politicians in Europe, Australia, and Japan have all rejected the evidence that the chemical is harmful as methodologically flawed, badly conducted or irrelevant – with some warning that banning it could actually endanger the public. Now that the National Institutes of Health has acknowledged it funded a lot of poorly-designed research on BPA – the very research that activists touted as evidence that the chemical is deadly – it’s time to ask whether America has been spun by clever marketing rather than clever science.” *
If the media are not fulfilling their role as watchdogs, we will need to look for new watchdogs, perhaps in science-based, non-profit organizations like STATS, with no stories to sell and no axe to grind.
* From ‘Science Suppressed: How America beca
me obsessed with BPA’ http://stats.org/stories/2009/science_suppressed_BPA_intro_jun12_09.html