Allergic contact dermatitis is similar to contact dermatitis except that the skin becomes sensitized to certain chemicals and the allergy usually persists throughout the life of the affected person. Once someone comes in contact with the substance again, the symptoms return. Some people are more likely to develop allergy from chemicals than others. Table 1.2 lists some important activities and situations in which one is likely to be exposed to chemicals through the skin. Normally they are taken in through eating, drinking or smoking.
Small children are more at risk as they sometimes try to eat anything they can lay their hands on.
Inadvertent exposure to chemicals through the food we eat is a very serious problem. Even nail biting can result in exposure to chemicals. The food we eat can become contaminated during processing, storage or transportation. The over-use of pesticides on vegetable and fruit crops may leave residues which can cause poisoning. Some toxic chemicals are taken in by fish, which may cause poisoning when contaminated fish products are consumed.