A URINE test that could demonstrate exposure to passive smoking in a child may soon be used to persuade guilty parents to give up the habit. The test, which could be carried out by general practitioners, measures the level of cotinine and other forms of nicotine in the child's urine. Cotinine occurs at high levels in passive smoking and can still be detected in the urine four days after exposure to environmental smoke.

Developers of the test, from the Wolfson Laboratory at the Queen Elizabeth Medical Centre, Birmingham, say in General Practitioner that it could convince parents of the harm they are doing.