Table 1.

Births, congenital anomalies, and standardized risk ratios (95% CIs) within 2 km of the landfill sites, 1983–1997.

	Before			After
Sites	Congenital anomalies	Total births	Standardized risk ratio	Congenital anomalies	Total births	Standardized risk ratio	Ratio after:before
Before opening and after opening of sites	182	14,230	0.87 (0.75–1.00)	173	15,451	1.21 (1.04–1.40)	1.39 (1.21–1.72)
As above but including four sites with significant expansion	223	16,948	0.89 (0.78–1.01)	202	17,860	1.22 (1.06–1.39)	1.38 (1.13–1.67)
Fifteen sites introducing containment after opening	12	766	1.11 (0.64–1.81)	102	8,097	1.27 (1.05–1.53)	1.15 (0.63–2.29)
Eight sites with containment but no gas control	3	380	0.79 (0.29–1.90)	28	2,757	1.16 (0.81–1.63)	1.47 (0.45–7.56)
Ten sites introducing gas control after opening	64	3,617	1.39 (1.09–1.75)	20	2,310	1.03 (0.67–1.52)	0.74 (0.42–1.24)
Three sites with gas control but no containment	1	113	—	0	88	—	—
Six sites that accept chemical waste	38	2,358	1.15 (0.84–1.55)	43	4,319	1.25 (0.93–1.65)	1.08 (0.68–1.72)

—, Numbers are too small to quote reliable CIs.