One of the purposes of educating our students is to help them to make sense of newspaper articles about ‘Chemistry’. Almost every day there is some scare that involves the use of ‘nasty chemicals’ – how seriously should we take these? There is no right answer to this question as each case must be judged on its own merits but hopefully we can provide our students with the tools to make their own sensible conclusions.

In today’s Daily Mail there is an article about how your clothes can poison you. This is not really new as a similar report appeared in the New York Times in December 2010. Basically the articles claim that manufacturers put formaldehyde into clothes to make them smell fresh and keep them wrinkle free. They then go on to state that “formaldehyde, a highly toxic, colourless gas, has been linked to skin irritation and allergic reactions. Even more worryingly, the chemical is classified as a human carcinogen by the International Agency for Research on Cancer.”

So how valid are these claims?  Formaldehyde is of course the old name for what we now call methanal. Our students are likely to come across methanal both in biology (formalin, used to preserve specimens, is methanal in water) and in Topics 10, 20 and Option G: Further organic chemistry. They may, or may not, actually handle it practically. Since it is a gas most teachers use propanal or butanal rather than methanal as an example of an aldehyde in practical work. Even so, students will be breathing in methanal in their daily lives as it is found both naturally and as an ingredient in certain wood products such as plywood and fibreboard, in foam insulation and paints, varnishes and glues. It is also present in automobile exhaust.

Methanal is certainly toxic to humans if ingested and breathing in concentrations above 0.1 ppm in air has been shown to irritate the eyes. In those people who suffer from certain allergies it may cause headaches and breathing difficulties even at this low level. The evidence that it is carcinogenic is less certain but is sufficient for methanal’s status to have been upgraded from ‘reasonably anticipated to be a human carcinogen’ to ‘known to be a human carcinogen’ by the US National Toxicology Programme’ as recently as June 2011.

It seems on balance that the newspaper articles are right to be concerned. Why expose yourself to unnecessary amounts of methanal? It makes sense to wash and air new clothes thoroughly before wearing them or hanging them in your wardrobe. Alternatively, in these times of economic hardship, perhaps it is even worth considering wearing ‘hand me downs’ or frequenting charity shops.