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Risk of congenital anomalies after the opening of landfill sites.

Article Excerpt
Concern that living near a particular landfill site in Wales caused increased risk of births with congenital malformations led us to examine whether residents living close to 24 landfill sites in Wales experienced increased rates of congenital anomalies after the landfills opened compared with before they opened. We carried out a small-area study in which expected rates of congenital anomalies in births to mothers living within 2 km of the sites, before and after opening of the sites, were estimated from a logistic regression model fitted to all births in residents living at least 4 km away from these sites and hence not likely to be subject to contamination from a landfill, adjusting for hospital catchment area, year of birth, sex, maternal age, and socioeconomic deprivation score. We investigated all births from 1983 through 1997 with at least one recorded congenital anomaly [International Classification of Diseases, Ninth Revision (ICD-9), codes 7400-7599; International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10), codes Q000-Q999]. The ratio of the observed to expected rates of congenital anomalies before landfills opened was 0.87 [95% confidence interval (CI), 0.75-1.00], and this increased to 1.21 (95% CI, 1.04-1.40) after opening, giving a standardized risk ratio of 1.39 (95% CI, 1.12-1.72). Enhanced congenital malformation surveillance data collected from 1998 through 2000 showed a standardized risk ratio of 1.04 (95% CI, 0.88-1.21). Causal inferences are difficult because of possible biases from incomplete case ascertainment, lack of data on individual-level exposures, and other socioeconomic and lifestyle factors that may confound a relationship with area of residence. However, the increase in risk after the sites opened requires continued enhanced surveillance of congenital anomalies, and site-specific chemical exposure studies. Key words: congenital malformations, epidemiology, landfill, small-area health statistics. Environ Health Perspect 113:1362-1365 (2005). doi: 10.1289/ehp.7487 available via http://dx.doi.org/[Online 14 June 2005]

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The possibility of adverse health effects of living near landfills has become a major public health issue (Dolk et al. 1998; Elliott et al. 2001; Fielder et al. 2000a, 2000b). The EUROHAZ-CON study of hazardous waste landfill sites in five European countries found a 33% increase in the risk of congenital abnormalities in infants born to mothers living within 3 km of the sites (Dolk et al. 1998). The Small Area Health Statistics Unit study of more than 19,000 landfill sites in Great Britain (Elliott et al. 2001) showed a statistically significant but very small (1%) increase in congenital anomalies in babies born to women living within 2 km of any landfill site. The authors acknowledged that this U.K. national study suffered from problems in the accuracy of environmental data and from the possible bias of differential underreporting of congenital anomalies by hospitals.

Our present study arose from health concerns expressed by residents that chemicals emitted from a single landfill site in the Rhondda Valley, Wales, were the cause of congenital anomalies. These fears led to a major public outcry, direct action, a public inquiry (Purchon 2001), and an international review by the Agency for Toxic Substances and Disease Registry (2003). In preliminary epidemiologic studies we found that rates of notified congenital anomalies in the local government areas where complaints of smells occurred were significantly higher than rates in socioeconomically matched control areas, but this was the case before as well as after the landfill opened (Fielder et al. 2000b). We therefore carried out a new study to test the null hypothesis that the opening of new landfills in Wales was not associated with increased rates of congenital anomalies in nearby residents by comparing rates before and after sites opened. Validation of environmental data parameters was undertaken with the help of local government personnel and the government-funded Environment Agency. We also adjusted for the potential bias caused by differential underreporting of congenital anomalies by different hospitals.

Materials and Methods

Birth data. Cases of statutorily notifiable congenital anomalies were obtained from the U.K. Office of National Statistics for 1983 to 1997. All births with at least one recorded anomaly with International Classification of Diseases, Ninth Revision [ICD-9; World Health Organization (WHO) 1979] and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10; WHO 1994] codes in the range of 7400-7599 for ICD-9 and Q000-Q999 for ICD-10 were included. Subgroup analysis was carried out for two major groups where numbers of cases were reasonably large, namely, chromosomal anomalies...

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