The risk of birth defects such as Down's syndrome is 40 per cent higher for pregnant women living within three kilometres of hazardous waste landfill sites, according to new research. Its authors call for more measurement of the exposure of people living near landfills to chemicals.
The report follows a number of studies linking birth defects to living adjacent to hazardous waste dumps. This latest research by Dr Martine Vrijheid of the London School of Hygiene and Tropical Medicine is published this morning in the Lancet.
The researchers used data collected in 1998 as part of the "Eurohazcon" study, which looked for non-chromosomal birth defects such as cleft palate and spina bifida in those living near dumps. That earlier work showed a 33 per cent increased risk of these defects in those living within three kilometres of a hazardous dump.
The new study looked for chromosomal defects leading to conditions such as Down's syndrome and it identified a significantly increased risk. The detailed analysis included 23 landfill sites in five EU countries and identified a 40 per cent higher risk.
The team looked at 245 cases of chromosomal defect and another 2,412 healthy individuals, and made statistical adjustments so that the mother's age when pregnant and socio-economic factors did not distort the results.
It compared risks for those living within three kilometres and between three and seven kilometres away from a hazardous dump. These distances were chosen on the advice of landfill specialists as zones of "most likely exposure" to substances coming from the dumps.
Dr Vrijheid found that the increased risk of both chromosomal and non-chromosomal defects remained similar when results were pooled or when separated into individual areas.
The similarity could be interpreted in two ways, she suggested. Either landfill exposures are causally related to risk of congenital defects or it was a chance effect arising from those chosen as healthy controls. She ruled out hidden socio-economic factors because these influence chromosomal and non-chromosomal defects differently.
The mother's age when pregnant can increase the risk of conditions such as Down's but Dr Vrijheid also ruled this factor out. After adjusting for age, the risk of chromosomal defects increased for those living near the dumps.
The study could not measure how much, if any, exposure mothers had to chemicals from the landfills.
