Green Chemistry

Chemicals of one sort or another feature in all physical products, be it cleaning sprays or smartphones. Generally there is no or little risk to consumers if products are used correctly. However, some chemical ingredients have become notorious for negative health effects only observed after many years of exposure, or the consequence of these chemicals in the environment. Examples include the following:

• Bisphenol A (BPA) is a component of food packaging and bottles. It is thought to mimic estrogen and interfere with hormone regulation in the body (albeit weakly). For this reason it has been removed from baby bottles.

• Radium is a radioactive element, discovered by Marie Curie and once used in radiotherapy. Radium was also a key component of the paint used to make glow-in-the-dark products, particularly clocks and watches. This created the phenomenon of 'Radium Girls', who would work with the radioactive substance in production lines. Although considered glamorous work at the time, it resulted in horrific illnesses due to radiation poisoning. A landmark court case consequently improved worker rights and health and safety rules.

• Tetraethyllead was a highly effective fuel additive. Unfortunately tetraethyllead is volatile and leads to lead poisoning (lead being a neurotoxin). Tetraethyllead has actually been associated with a spate of serial killers in 1970s California (although not conclusively). This prompted the introduction of 'unleaded petrol'.

• Chlorofluorocarbons (CFCs) are a class of chemical refrigerants and propellants synonymous with 1980s hair spray. They are incredibly effective but had the unintended consequence of damaging the ozone layer. In response, the Montreal Protocol banned ozone depleting substances and the ozone layer is recovering.

As an aside, Thomas Midgley Jr. was a key scientist in the invention of tetraethyllead and CFCs. He is now a much-maligned figure, the enormous environmental impact of these chemicals overshadowing what an amazing achievement these inventions were. What we must remember is that, at the time, environmental impact was not a criteria in the design of these products and nor was it understood until later.

The response to the above chemical hazards has been to substitute with an alternative substance that performs the same function. In some cases, what is known as 'regrettable substitution' has occurred. This is when the original substance is banned or suspected of having concerning properties and is replaced by a different but still hazardous substance only to avoid regulation or public scrutiny. Regrettable substitution can be avoided if more toxicological testing is performed, and the design criteria for products embraces Green Chemistry.