One of the largest studies of childhood cancer ever carried out in Britain (22,400 children who died between 1953 and 1980) established strong links between birthplace and death from leukaemia and other childhood cancers. The children’s birthplace was more important than where they grew up in setting a risk.

The highest risks were within three miles of oil refineries (petrol fumes), car factories (principally paint spray), steel works, cement works and crematoria and power stations. (Except for a few exceptions, nuclear power stations did not appear to have a significant risk.) Additional risk was also found within 2.5 miles of motorways and railways (petrol and diesel fumes). The scientists also considered proximity to (i) petrol stations, (ii) bus stations, and (iii) school and hospital chimneys a increased hazard.

The study found that the increased risk around factories was constant over many years, giving the lie to the hypothesis that clusters of illness could be attributed to a sudden influx into an area of building workers carrying viruses new to the area. The persistent excesses could only be attributed to environmental factors.

The researchers concluded that exposure of pregnant women and young babies directly to airborne pollutants was the most likely mechanism by which the excess cancer clusters were caused. The way the pollutants combined with each other to form secondary pollutants was also significant.