Elliott et al. (2001a,b) included about 80% of the UK population residing within 2 km of 9565 landfill sites (7803 non-special, 774 special, 988 unclassified) between 1983 and 1998. Given the influence of confounding factors and data artefacts, no clear cause could explain the slight excess risk of birth defects and low birth weights that was found.