Bitter truth behind a sweet-smelling candle? Toxic formaldehyde

WITH the winter wind howling at the door, the prospect of battening the hatches and lighting a scented candle for comfort may well sound appealing.

But research suggests the treat may come hand in hand with potentially dangerous levels of the toxic substance formaldehyde. A study by Prof Alastair Lewis of the National Centre for Atmospheric Science at the University of York found that an ingredient commonly used to give candles their scent mutates upon contact with the air.

The suspect ingredient is limonene, which gives off a citric aroma. In its unaltered state, it is safe to use in flavouring food, and gives cleaning products and air fresheners a lemony scent.

But limonene reacts with naturally occurring ozone when released into the air, causing one in every two limonene molecules to become formaldehyde.

While it is already well known that limonene, which occurs naturally in plants, can degrade into formaldehyde, almost every test into its harmful impacts was carried out decades ago.

Prof Lewis found concentrations of limonene in scented candles up to 100 times higher than previously thought.

He said: “The really surprising thing is just how high the concentrations of some fragrances are now in people’s homes. Fragrance chemicals now completely dominate the inside of most homes. The issue is: we don’t really know what the consequences of longterm exposure to formaldehyde are … It is a chemical that is known to harm you long term,” he added.

The Health Protection Agency lists formaldehyde as a possible human carcinogen, as well as being toxic and corrosive. It can also cause nosebleeds, sore throats, coughs and stinging eyes.

Prof Lewis described limonene as a bulk chemical that is commonly found in higher concentrations in cheaper products such as floor cleaners and air fresheners as well as candles.

He said it is most commonly found in offices where cleaning products tend to be “sloshed around”.

The best way to combat the risk is to open doors and windows after using a scented candle or spraying air freshener, he added.