The findings are based on an analysis of births in Cumbria, north west England, between 1956 and 1993. During this period, there were almost 245 000 births, of which 3234 were stillborn, and 1569 had congenital abnormalities. A further 2663 babies died shortly after birth.
There was no increased risk of stillbirth or death shortly after birth, overall, among babies whose mothers lived near incinerators. But after taking account of influential factors, such as birth order and multiple births, the risk of neural tube defects, particularly spina bifida, was 17% higher and heart defects 12% higher.
When the analysis concentrated on birth defects and stillbirths in the period before the incinerators were operational, no increased risk was found.
The risk of stillbirth was 4% higher and the risk of the life threatening brain abnormality anencephalus was 5% higher among babies whose mothers lived near to crematoria.
The authors point out that the introduction of antenatal screening and termination of pregnancy would have reduced the number of potential stillbirths and babies born with lethal congenital abnormalities in recent years. Added to which, the lack of data on pregnancies of under 28 weeks could have underestimated the extent of serious and lethal birth defects
Incinerators and crematoria may emit harmful chemicals, including dioxins, although little is known about the long term effects of prolonged low dose exposure. But because of a lack of emissions data, no definitive conclusions can be drawn on the biological plausibility of the findings.
The study does not provide conclusive evidence of a causal effect, but, nevertheless, the statistical findings bear further investigation, say the authors. This is especially in view of the fact that so few comparable studies have been carried out, and that incineration is becoming more widely used as a method of waste disposal.
[Adverse pregnancy outcomes around incinerators and crematoriums in Cumbria, north west England, 1956-93 2003; 57: 456-61]