It was reported in the UK that children living in households using hanging insecticidal strips were at almost twice the risk of developing leukaemia. This rises to three times the risk if the strips were used in the last three months of pregnancy. Dichlorvos, the main insecticide used in hanging strips, is classified by the US Environmental Protection Agency as a human carcinogen. Organophosphate pesticides are also used in hanging insecticide strips and pets' flea collars. They enter the body mainly through the skin but also on the breath.
A US study showed that dogs are twice as likely to develop cancers if their owners treated their lawns with 2,4-D, the main weedkiller used in household gardens. 2,4-D has already been linked with cancer in farm workers by several studies.