Health effects of landfill sites

Editor—Fielder et al reported increased rates of congenital malformations in the area surrounding the Nant-y-Gwyddon landfill site, having examined five “exposed” wards and 22 comparison wards.¹ They imply that their findings are relevant to landfill sites receiving domestic, commercial, and industrial waste in general rather than being specific to the Nant-y-Gwyddon site.

Studies such as this are subject to several scientific constraints.² Paramount among these are that comparison populations should not be exposed to potential risks from landfill sites and that exposed areas should be relatively unaffected by alternative potential pollutant sources.

Examination of site licence records suggests that there are up to seven other operating or closed landfill sites whose zones of potential influence include the comparison wards, including sites receiving similar wastes to the Nant-y-Gwyddon site. Given the absence of comment from the authors, we conclude that these sites are not having any measurable effects. Hence the study seems to show that one landfill site may have certain health effects while seven others do not.

Health concerns have been expressed about incinerators,³ particularly the older generation of municipal waste incinerators, which operated without modern emissions controls. A former municipal waste incinerator was located about 2 km to the southeast of the exposed area. We understand that it operated from 1974 and was decommissioned in 1987. Fielder et al's study shows a peak in rates of congenital anomaly in 1988 and 1989 in the exposed wards. We further understand that an older combustion plant had operated at roughly the same location since 1916. The more recent incinerator handled the area's municipal waste before the opening of the Nant-y-Gwyddon landfill site and was apparently closed because of local complaints, poor performance, and air pollution.

The incinerator was located in a steep northwesterly valley running through the exposed wards, and atmospheric emissions probably extended into the study area. As Fielder et al provide no direct evidence that the Nant-y-Gwyddon landfill site is the cause of the raised rates of congenital malformations, it could be equally asserted that the incinerator is a material factor, although there may be other causal factors.

We would suggest a refinement of Fielder et al's final recommendation: that protocols be developed to measure community exposures systematically in areas where raised rates of congenital anomalies have been identified. To pre-empt the findings of such exposure studies with an assumption that the cause is landfill seems to miss an important opportunity to answer the question of what causes the health effects and hence to resolve the legitimate concerns of local residents.