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Health outcomes in populations living close to landfill sites. The Small Area Health Statistics Unit (SAHSU), Department of Epidemiology and Public Health, Imperial College. Lars Jarup, David Briggs, Cornelis de Hoogh, Christopher Hurt, Tina Kold Jensen, Sara Morris,
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Health outcomes in populations living close to landfill sites The Small Area Health Statistics Unit (SAHSU), Department of Epidemiology and Public Health, Imperial College Lars Jarup, David Briggs, Cornelis de Hoogh, Christopher Hurt, Tina Kold Jensen, Sara Morris, Jon Wakefield and Paul Elliott
Modelling exposures from landfill sites: Methods and issues The Small Area Health Statistics Unit (SAHSU), Department of Epidemiology and Public Health, Imperial College Cornelis de Hoogh, David Briggs, Christopher Hurt, Lars Jarup and Paul Elliott
Background • Excess risk of adverse birth outcomes and certain cancers have been reported, primarily in the USA (hazardous waste sites) • Low birthweight (Goldberg et al, 1995; Kharazzi et al, 1997; Berry and Bove, 1998) • Stillbirth (Kharazzi et al, 1997) • Congenital anomalies (Geschwind et al, 1992, Croen et al, 1997) • Mallin, 1980 (bladder cancer) • Goldberg et al, 1995 (several cancers including liver) • Willams et al, 1998 (brain cancer)
Background • Two recent European and UK studies • EUROHAZCON (1998) • neural tube, cardiac and vascular defects • decrease in risk by distance, BUT • several landfills in “reference area” not accounted for • Nant-y-Gwyddon (2000) • increased risk of malformations also before site opening
Aims • Primary objectives: to test the hypotheses that living near a landfill site is associated with excess risk of congenital anomalies, stillbirth, low birthweight or very low birthweight • Secondary objective: to test the hypothesis that living near a landfill site is associated with an excess risk of certain cancers
Industrial emissions Atmospheric dispersion Inhalation Vehicle emissions Gaseous emissions Mineral dusts Prior land use Waste disposal Capping/ restoration After-use Excavation Solid waste Animal/bird dispersion Dermal contact Waste handling Soil contamination Aqueous emissions Drainage/ Leaching Water pollution Ingestion Runoff Plant uptake Click for larger picture
Analyses • Effects of socio-economic status and other explanatory variables • urban-rural differences • maternal age (for abdominal wall defects) • Landfill sites classified as receiving ‘special’ (hazardous) or ‘non-special’ waste • Periods before and after opening of landfill sites • Poisson regression • 99% confidence intervals
Study area • “Exposed” population defined as living within 2 km from a landfill site • 80% of the national population • Likely limit of dispersion (WHO 2000) • 1 - 2 km depending on pathway
19,196 landfill sites x 1.6 million postcodes x 16 years x 2 lag periods = 1011 buffering operations!
Most affluent Intermediate Most deprived Exposed 30.4 34.2 35.3 Unexposed 43.1 32.4 24.4 Excluded 35.2 33.2 31.5 Exposure by socio-economic status
Discussion • The largest study to report on the possible association between residence near landfill and health outcomes • Deprivation adjustment may incompletely account for individual-level characteristics associated with risk of congenital anomalies and cancers • Need to take account of the complexity of the system, and data limitations, in using GIS for exposure assessment
Conclusion • 80% of population live within 2km of a landfill site • No causal mechanisms currently available to explain our findings • Alternative explanations possible • data artefacts • residual confounding • Further understanding of the potential toxicity of landfill emissions and possible exposure pathways is needed in order to help interpret the epidemiological findings
References • Elliott P, Briggs D, Morris S, de Hoogh C, Kold Jensen T, Maitland I, Richardson S, Wakefield J, Jarup L. Risk of adverse birth outcomes in populations living near landfill sites. BMJ 2001;323:363-8. • http://www.bmj.com/ • http://www.doh.gov.uk/whatsnew/index.html