Passive smoking in childhood may increase the risk of nasal cancer, says a study of children whose parents had lung cancer. The incidence of bladder and kidney cancer was also greater in the offspring, possibly as a result of exposure to tobacco carcinogens either in the womb or through breast feeding, say researchers writing online in the International Journal of Cancer on 10 August (http://www3.interscience.wiley.com/, doi: 10.1002/ijc.21387).

Although the carcinogenic effects of active smoking have been seen at many sites, the effects of passive smoking and exposure in pregnancy and breastfeeding are less well documented, say the researchers.

The authors used …