Fall, 1997
Birth Defects and Superfund Sites
New research suggests increased risk for certain birth defects when women live very close to Superfund sites in early pregnancy. The study by the CA Birth Defects Monitoring Program (CBDMP) looked at three common birth defects: neural tube defects (spina bifida and anacephaly), conotruncal heart defects (a group of serious heart defects), and cleft lip and cleft palate. Study findings suggest that women who lived with in 1/4 mile of a Superfund site during the first three months of pregnancy were four times more likely to give birth to a baby with serious heart defects, and 2 times more likely to give birth to a baby with neural tube defects. Children born with cleft lip and cleft palate occurred no more frequently than expected. Women who lived further than 1/4 mile from the sites were not at higher risk.
Researchers say the results are reinforced by similar findings in other studies but cannot be considered definitive because of the small number of women living very close to the sites. Even with the small number of women living close to Superfund sites, the study itself was comprehensive. In the largest study of its kind, the CA Birth Defects Monitoring Program interviewed more than 200 mothers, including those with healthy babies in a wide area across California. It was the first investigation to focus on the vulnerable months surrounding early pregnancy when these birth defects occur. And it took into account other issues such as lack of vitamin use, cigarette smoking, race/ethnicity and socio-economic status.
How many women are affected by the higher risk? Only 0.6% of the mothers interviewed lived within 1/4 mile of a Superfund site during early pregnancy. About half of these women lived on military bases. The study couldn't measure whether mothers were actually exposed to chemicals from those sites. "It's hard to study these chemical soups", said the study author, Lisa Croen, PhD of the CBDMP. Superfund sites are those on the National Priority List targeted for cleanup. Of the 1400 sites in the US, 105 are in CA and the county having the most (29), is Santa Clara County. Sites include inactive pesticide and chemical manufacturing plants, wood processing facilities, drum storage sites, contaminated groundwater areas, sanitary landfills and mines. Military bases make up 20% of California's Superfund sites.
The small number of cases around hazardous waste sites means the findings do not have strong statistical power. However, they do support early research hinting at higher risk. The higher risk for certain birth defects are relevant as communities plan development around hazardous waste sites or re-use of these sites.
Source: CA Dept. of Health Services Press Release and CBDMP Info Packet (6/16/97)
CBDMP is a public health program devoted to finding causes of birth defects and is funded through the CA Dept. of Health Services and jointly operated with the March of Dimes Birth Defects Foundation. For more information, or to obtain a copy of the study, call CBDMP at 209-224-2212
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