Bisphenol A (also known as BPA) has been used for decades to make a variety of plastic products such as toys, bottles, food containers, and the protective coating inside many food and beverage cans.
It is a controversial chemical. There are growing concerns – and scientific evidence – that it can threaten human health. But representatives of the chemical industry says that products containing bisphenol A are safe for their intended uses and pose no known risks to human health.
Bisphenol A was first suspected to be harmful in the 1930s but it is only in recent years that governments have begun to control it.
Experiments with animals have linked bisphenol A to obesity, cancer and infertility, and have suggested that the chemical may be an endocrine disruptor.
In recent years a number of studies have linked bisphenol A to a wide range of health effects in people too.
A 2008 study of 1,455 adults in the United States found that 90 percent had bisphenol A in their urine. The more bisphenol A they had, the greater their risk of cardiovascular disease and type II diabetes, though this does not prove a cause.
Other studies in both rodents and people suggest that bisphenol A may interfere with the female sex hormone oestrogen. It has been linked with interference of normal foetal development.
Bisphenol A can leach out of plastics when they are heated – as in a microwave or dishwasher – and this increases the risk the chemical poses.
The US National Toxicology Program has concluded that the main source of exposure is when consuming food and drink.
As babies and small children are at greatest risk from toxic chemicals than adults, there is special concern about the use of plastic bottles for feeding them, especially if these are heated in a microwave or cleaned in a dishwasher.
Despite these concerns, many government regulators have concluded that most people will never experience a dangerous level of exposure. The World Health Organization, however, is organizing an expert consultation in 2010 to assess the safety of bisphenol A.
Some companies have stopped selling products containing bisphenol A and in 2008 Canada became the first country to ban the import and sale of baby bottles containing the substance.
Consumers can reduce their exposure by using glass, steel or porcelain containers for food and liquids, and by avoiding putting products containing bisphenol A in a microwave or dishwasher.
Some scientists and pressure groups are calling for products to be clearly labelled if the contain the chemical but so far this has not been adopted except in Canada.
Plastics with the recycling labels #1, #2 and #4 on the bottom are safer choices as they never contain bisphenol A, which is most likely to be found in plastics with the recycling label #7.
Journalists reporting on bisphenol A should be familiar with any national regulations that control its use.
When investigating possible health threats to consumers reporters can start by checking with manufacturers to find out the bisphenol A content of their products.
As with all chemicals, journalists should take care when relating the results of animal experiments to conclusions about health threats to people.
In some experiments, researchers expose animals such as rats to doses of chemicals that are often much higher than those that people would ordinarily experience.
It is important to check with researchers what the equivalent dose in humans would be, and how likely it would be for people to get such an exposure.
Journalists should also take care when assessing the sources of research and news about bisphenol A. The Bisphenol-A and Facts about BPA websites, which say the chemical is safe, have been set up by the American Chemistry Council, which represents North American chemical manufacturers.
Equally, some organizations that call for strict controls of bisphenol A may be exaggerating the scale of the threat.
In 2009, journalists at the Milwaukee Journal Sentinel in the United States won several national prizes for their series “Chemical Fallout” which highlighted the risks from bisphenol A in commonly used products.
Reporters Meg Kissinger and Susanne Rust highlighted weaknesses in government regulation and showed that the chemical leaked even from products labelled as microwave-safe.
The articles prompted some retailers to stop using bisphenol A in plastic bottles. Meanwhile new legislation aimed at banning the chemical in food and drink containers was submitted to both houses of the US Congress.
In these and later articles (here and here) the journalists showed that existing government regulations had been heavily influenced by lobbyists for the producers of bisphenol A, whose sales are worth billions of dollars each year.
They predict that the industry will launch an aggressive public relations campaign to persuade the public that bisphenol A is safe to consumers and to dissuade legislation and regulation that would affect its business.
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