It seems that our love of cheap, light, and colourful plastics is doomed. Just when conscientious consumers switched to reusable water bottles and coffee mugs, even more damning evidence comes to light.

Polycarbonate plastic contains Bisphenol A (BPA), which is also used in the manufacture of epoxies. These substances are hard, durable, resistant to heat, and non-reactive, yielding a diversity of possible uses. Products include reusable water bottles, baby bottles, dental sealants, and the linings of both food cans and water pipes. In addition, CDs, DVDs, electrical and electronic components, paints, adhesives, and many other items use these BPA-enhanced plastics and epoxies. In fact, 2.8 million tons of BPA was produced in 2002, reflecting its ubiquitous use.


The problem lies in BPA’s activity as an endocrine disruptor. This substance mimics natural estrogens found in the body, thereby changing the normal function of the endocrine system. The results can include lowered sperm count in men and other male animals and is implicated in both testicular and breast cancers.

The newest study looked at the effect of liquid temperature on the release of BPA. Previous research has shown that BPA leaches out of plastic when it is weathered, through abrasion of the surface (like scrubbing and dishwasher wear), exposure to sunlight, and heating through boiling. In fact, when polycarbonate bottles are used to hold boiling water, BPA release increases by a factor of up to 55 times. With cold liquids, 0.2-0.8 nanograms of BPA were released per hour. But after exposure to boiling water, this increased to 8-32 nanograms per hour.

Researchers used new and used bottles to compare the normal effects of wear on BPA levels. They did not see any difference between brand-new and nine-year-old bottles. But both groups showed the same dramatic rise in BPA leaching with boiling water. The study is published in Toxicology Letters.

BPA has been tested for toxicological effects in the lab. Small amounts can cause early sexual maturity, decreased male fertility, immune system changes, brain changes, and behavioural effects - including hyperactivity, aggression, and impaired learning - in rats and mice. In aquatic environments, estrogen mimics are associated with reproductive changes, nutrient absorption, and other endocrine systems. However, there is no consensus in the scientific community about its effects on humans.

Other endocrine disruptors, particularly estrogen-mimics, include phytoestrogens - found in soy, garlic, rice, wheat, carrots, potatoes, cherries, apples, and other produce. Synthetic forms include the notorious DDT, atrazine, lindane, PCBs, and other organochlorine used in industry and as pesticides.

Occasional exposure to BPA is not considered problematic, as it is rapidly metabolized. But this does not address the widespread presence of low levels throughout the environment - from food and water to homes and businesses. This constant barrage of small amounts of BPA and other endocrine disruptors may be the issue. Despite their pretty colours and convenience, it may be time to turn away from our polycarbonate bottles and call for alternatives in our canned edibles.