Pervasive plastics

The true costs of plastics - including the energy required to manufacture them, the environmental contamination caused by their disposal, their health impacts, and the recycling and eventual disposal costs - are not reflected in product prices. The American Plastics Council now estimates that only about 5 per cent of all plastics manufactured are recycled; 43 billion kilos are discarded on average yearly. Adding to the environmental toll, most plastic is produced from natural gas and petroleum products, exacerbating global warming.

Plastics and human health

The controversy over BPA - the primary component of hard and clear plastics - and its potential role in human hormone disruption provides the most recent example of the need for a national plastics control law.

Normal growth and development among fetuses, infants, children, and adolescents is regulated in the body by a diverse set of hormones that promote or inhibit cell division. More than a thousand chemicals are now suspected of affecting normal human hormonal activity. These include many pharmaceuticals, pesticides, plasticisers, solvents, metals, and flame retardants.

Scientists’ growing interest in hormone disruption coincided with a consensus within the National Academy of Sciences that children are often at greater risk of health effects than adults because of their rapidly growing but immature organ systems, hormone pathways, and metabolic systems. And many forms of human illness associated with abnormal hormonal activity have become more commonplace during the past several decades, including infertility, breast and prostate cancer, and various neurological problems.

BPA illustrates well the endocrine disruption problem. Each year several billion kilos of BPA are produced in the United States. The Centers for Disease Control and Prevention has found, in results consistent with those found in other countries, that 95 per cent of human urine samples tested have measurable BPA levels. BPA has also been detected in human serum, breast milk, and maternal and fetal plasma. BPA travels easily across the placenta, and levels in many pregnant women and their fetuses were similar to those found in animal studies to be toxic to the reproductive organs of the animals’ male and female offspring.

Government scientists believe that the primary source of human BPA exposure is foods, especially those that are canned, as BPA-based epoxy resins can migrate from the resins into the foods. In 1997, the FDA found that BPA migrated from polycarbonate water containers - such as the five-gallon water jugs found in offices - into water at room temperature and that concentrations increased over time. Another study reported that boiling water in polycarbonate bottles increased the rate of migration by up to 55-fold, suggesting that it would be wise to avoid filling polycarbonate baby bottles with boiling water to make infant formula from powders.

Scientists have reported BPA detected in nonstick-coated cookware, PVC stretch film used for food packaging, recycled paperboard food boxes, and clothing treated with fire retardants.

Since 1995 numerous scientists have reported that BPA caused health effects in animals that were similar to diseases becoming more prevalent in humans, abnormal penile or urethra development in males, obesity and type 2 diabetes, and immune system disorders. BPA can bind with oestrogen receptors in cell membranes following part-per-trillion doses - exposures nearly 1,000 times lower than the EPA’s recommended acceptable limit.

In 2007, the National Institutes of Health convened a panel of 38 scientists to review the state of research on BPA-induced health effects. The panel, selected for its independence from the plastics industry, issued a strong warning about the chemical’s hazards:

There is chronic, low level exposure of virtually everyone in developed countries to BPA ... The wide range of adverse effects of low doses of BPA in laboratory animals exposed both during development and in adulthood is a great cause for concern with regard to the potential for similar adverse effects in humans.

The American Chemistry Council, which advocates for the plastics industry, has criticised most scientific research that has reported an association between BPA and adverse health effects. The council’s complaints have included claims that sample sizes are too small, that animals are poor models for understanding hazards to humans, that doses administered in animal studies are normally far higher than those experienced by humans, that the mechanism of chemical action is poorly understood, and that health effects among those exposed are not necessarily “adverse”.

Research on plastics, however, now comprises a large and robust literature reporting adverse health effects in laboratory animals and wildlife at even low doses. Claims of associations between BPA and hormonal activity in humans are strengthened by consensus that everyone is routinely exposed and by the rising incidence of many human diseases similar to those induced in animals dosed with the chemical. Two competing narratives - one forwarded by independent scientists and the other promoted by industry representatives - have delayed government action to protect the health of citizens through bans or restrictions.