With growing awareness of the importance of personal hygiene in Hong Kong, many people, especially parents, don't leave the house without disinfectant wipes and hand sanitisers.

What they may not know is that many popular brands of disinfectant wipes contain some pretty harsh chemicals that can cause skin irritation and there may be health concerns associated with the overuse of wipes.

Dr Kelvin Leung, Associate Professor of The Department of Chemistry points out that there are basically two types of disinfectant personal hygiene products: alcohol and alcohol-free. Most of the alcohol-free products contain chemicals such as quarternary ammonium, chlorhexidine and triclosan which have the ability to halt the growth of harmful microorganisms but may not be able to kill them. "For example if there are 100 units of bacteria on your hands, 30 units still remain after using disinfectant wipes. The remaining bacteria will 'fall asleep' and the growth rate will decrease but the chemicals do not actually kill them. After a while the bacteria will 'wake up' and become active again."

Some animal model studies conducted in America have shown that exposure to triclosan is associated with unusual endocrine and hormone activity as well as tumour growth. Last year, the US Food and Drug Administration (FDA) finalised a rule that bans the use of triclosan in over-the-counter healthcare antiseptic products; however, there is no similar regulation in Hong Kong. Dr Leung adds, "Chemicals used as disinfectants kill all types of bacteria and it may spawn antibiotic-resistant strains of bacteria. In addition, products with added fragrance and preservatives may trigger allergies, so disinfectant products could actually be quite 'toxic'".

In order to kill harmful germs with no harmful effects, Dr Leung suggests using running water or rubbing alcohol for cleaning. "Rubbing alcohol can denature proteins within bacterium or virus. The most effective way to kill bacteria is to use 60%-80% alcohol, and due to its fast rate of evaporation, harmful chemicals will not be left on the skin. The best way to wash hands is age-old soap and water as all the dirt and harmful germs can be washed away. Disinfectant wipes and hand sanitisers are only suggested when there is no water supply. If running water is available, you are advised to wash again to ensure harmful chemicals do not stay on the skin." Dr Leung also reminds parents avoid using disinfectant products on infants and children as it can trigger allergies and the harmful chemicals are easily absorbed.