In The Graduate (1967) Mr McGuire approaches Dustin Hoffman's character Benjamin, fresh from university. "I just want to say one word to you. Just one word . . . plastics." McGuire was right. In 1967 the global production of plastic was less than 50 million metric tons; in 2013 it was 299 million metric tons, with a turnover of €320 billion.
However, a 2015 report predicted that 99 per cent of all seabird species would be chomping on it by 2050. It also noted that plastic pollutes oceans at concentrations of up to 580,000 chunks per square kilometre. Unsurprisingly, we humans host a diversity of plastic-related compounds, the health effects of which are keenly debated, none more so than bisphenol A (BPA).
BPA is used in resins lining food and drink cans and a constituent of cooking oil bottles and clear food packaging. Although typically consumed by ingestion, BPA can be absorbed through the skin or by inhaling dust.
BPA is an endocrine disruptor, mimicking the hormone oestrogen. According to the International Journal of Childbirth Education: "BPA has been linked to cancer, neuron damage, behavioural problems, and stunted health development in children."
A Taiwanese study in the journal Atherosclerosis last year investigated the relationship between blood serum concentrations of BPA in 886 people aged 12 to 30 years and the thickness of the innermost two layers of the carotid artery, the so-called carotid intima-media thickness (CMIT). It found that higher "serum concentrations of BPA were associated with increased CIMT".
However, the researchers stated that this “was a cross-sectional study; therefore we cannot infer causation”.
French ban
In January last year France became the first European country to ban BPA in all food and drink packaging.
Dr Wayne Anderson, director of food science at the Food Safety Authority of Ireland, says it is understandable that people may have concerns over the use of BPA in food contact plastics given the different scientific views expressed in the media and on the internet.
"But it's important that a view of risk is taken on the balance of scientific evidence rather than the findings of individual studies. The European Food Safety Authority [EFSA] has . . . concluded that BPA poses no health risk to consumers of any age group (including unborn children, infants and adolescents) at current exposure levels.
“The Food Safety Authority of Ireland concurs with this conclusion from EFSA and supports EFSA’s approach to keep the safety of BPA under close review.”
But in its “scientific opinion on the risks to public health related to the presence of bisphenol A [BPA] in foodstuffs”, the EFSA didn’t say that BPA posed “no health risk”. It said “there is no health concern for any age group from dietary exposure and low health concern from aggregated exposure”. The EFSA opinion made no fewer than nine recommendations for further research, acknowledging “the uncertainties surrounding this risk assessment of BPA”.
Toxico-pathologist C Vyvyan Howard, emeritus professor at the University of Ulster, said: "Animal studies where pregnant rats were exposed to 1/4 millionth of what is currently considered to be the 'no effect level' showed changes in the breast structure of the offspring. This has subsequently been shown to be pre-malignant.
“Other similar low-dose developmental studies have shown adverse effects on daily sperm production, obesity and behaviour.”
However, now adding to the debate is a growing number of studies suggesting that manufacturers are swapping BPA for chemical cousins that have the same troubling activities in humans and animals.
In a new study in Endocrinology, researchers found that a common BPA stand-in, bisphenol S (BPS), has nearly identical hormone-mimicking effects as BPA in zebrafish, a model organism used to study genetics and development.
In the study, researchers found that BPS, like BPA, altered nerve cell development, changed the activity level of genes involved in developing the reproductive system, and caused early hatching (the fish equivalent of premature birth).
Reduction in production
Howard encourages a reduction in the bulk production of all endocrine disrupting chemicals (EDCs). “The question is how much is dangerous,” he asks. “That is subject to continuing research but we can be confident that low doses are significant. There is an overwhelming case for removing any food contact uses of products containing EDCs.
“We are increasingly helping manufacturers with product reviews as they start to realise the potential for legal liability.”
In his book Don't Get Fooled Again, Richard Wilson considers the phrase "no measurable risk to health" in the context of asbestos safety. This phrase could mean "that there is (or may be) a risk, but that no precise measurement of that risk is possible", or that the "product poses no significant risk, and is essentially safe".
Wilson, perhaps, contributes much to the debate by pointing out the subtle difference “between an unknown danger and an insignificant one”.
In time we’ll know whether BPA constitutes and stand-ins are an unknown danger or an insignificant one.
