Cancer experts split over roads risk to children

New study finds excess deaths from living near pollution source

Cancer experts were divided last night over a new report which says that living near industrial sites or motorways could put children at increased risk of developing cancer.

A new study published today claims that children living near sources of atmospheric pollution, such as steel works or oil refineries, are 20 per cent more likely to die of leukaemia or other childhood cancers. It adds that there is also a "significant excess" of cases involving children who lived near motorways and railways.

But cancer charities and leading experts - including Sir Richard Doll who heads the current national study on childhood cancer [UKCCS] - dismissed the findings of Professor George Knox's study, saying that it made "no sense in a biological way or a methodological way".

Professor Knox's study - which appears in the Journal of Epidemiology and Community Health - looked at more than 22,000 children who died of cancer up to the age of 15 between 1953 and 1980. His team noted cancer rates in children by post code and then drew a map showing locations of power plants, refineries and factories.

They found a tendency for cancer cases near furnaces, refineries, car and battery factories, crematoria and power stations - although, with a few exceptions, nuclear power plants did not appear dangerous.

Near motorways and railways there were between 15 and 20 per cent more cases of cancer than would normally be expected, the professor said.

The authors concluded that childhood cancers were geographically associated with two main types of industrial pollution: volatile gases from petroleum and smoke and gas from kilns, furnaces and car engines. The study takes no account of other possible causes such as diet or cancer-carrying genes.

"If geographical clustering is genuine and not a demographic artefact, as is now clear, then it must reflect the existence of localised environmental hazards," Professor Knox wrote. "For a comprehensive single explanation we must favour direct exposure of pregnant women or young children to airborne substances diffusing into the surrounding environment."

He said industry could not eliminate all pollutants altogether, but once identified specific ones could be reduced and mothers could be warned against certain occupations.

But Sir Richard Doll said that Professor Knox's study was "hypothesis- forming but not conclusive" and he did not find the argument "compelling".

"It is an extremely complex methodology and he has not got a control study ... There is no obvious connection between industrial sites and cancer."

He said UKCCS would look at some of the hypotheses, of which the priority would be to look at whether living near main roads had significant results.

Professor Gordon McVie, director of the Cancer Research Campaign said he was "not greatly moved" by the study. "There is nothing particularly new in this. It is quite provocative in some ways ... but it doesn't all hang together."

He questioned the finding on motorways saying it was hard to believe that roads where cars pass quickly would bring about cancer clusters whereas those where cars emit more fumes from traffic jams would not.

Professor Ray Cartwright, head of Leukaemia Research Fund's department of clinical epidemiology and of the UKCCS epidemiologists, attacked the study for its methodology. "It uses postcode areas but we do not know how many people that covers ... We cannot accept this study as it is. You need to take individual people and look at their individual experiences."

Replying to the criticisms last night, Professor Knox said that his research was important and could now be used as a starting point to see if there was a better way of discovering the reasons for childhood cancer clusters: "It does make sense and it is the best methodology there is at the moment ... You can't throw away the facts because you don't like the theory."