Down Syndrome Abstract
of the Month: Apr 2002
Chromosomal congenital anomalies and residence near hazardous waste landfill sites
Vrijheid M, Dolk H, Armstrong B, Abramsky L, Bianchi F, Fazarinc I, Garne E, Ide R, Nelen V, Robert E, Scott JE, Stone D, Tenconi R.
Lancet 2002 Jan 26;359(9303):320-2
EUROCAT Central Registry, Environmental Epidemiology Unit, Dept. of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, UK.
Abstract:
Previous findings of the EUROHAZCON study showed a 33% increase in risk of non-chromosomal anomalies near hazardous waste landfill sites. Here, we studied 245 cases of chromosomal anomalies and 2412 controls who lived near 23 such sites in Europe. After adjustment for confounding by maternal age and socioeconomic status, we noted a higher risk of chromosomal anomalies in people who lived close to sites (0-3 km) than in those who lived further away (3-7 km). Our results suggest an increase in risk of chromosomal anomalies similar to that found for non-chromosomal anomalies.
My comments: Eurohazcon is a collaborative study among a number of congenital abnormality registries in Europe. Sixteen public health institutes were involved in the initial 1998 study (you can read it here). In this study, information about births of infants with chromosomal anomalies were obtained from England, Denmark, Belgium, France and Italy. 23 landfill sites were selected for their containing hazardous waste (as defined in a 1991 Eurocat document);a proximal zone was defined as being within 3 kilometers (1.8 miles) of the site, and compared with a distant zone of 3 to 7 kilometers away from the landfill. 245 cases of infants with chromosomal anomalies were identified, and compared with over 2000 control babies.
For all chromosomal anomalies, the odds of being near a site were 40% more likely than being distant from a site. For Down syndrome, the odds were 36% higher for living near the site.
So what does this mean? First, it doesn't mean any landfill, but only "hazardous waste" landfills (think Love Canal). Second, this study shows an association, not a cause-effect relationship.
There are some limitations to this study. Location of the babies was based on where the mothers lived when the babies were born, which may not have been where the babies were conceived. Another problem is that the study only uses 2 geographical areas; it would have been more meaningful to have more defined areas.
This research should be considered preliminary. To quote the author's final sentence: "More study into the chemical causes of chromosomal anomalies and exposure of residents to landfill sites is needed to interpret our findings."