The prevalence at birth of congenital malformations in communities near the Hanford site.

The authors examined the prevalence of congenital malformations among births in Benton and Franklin counties, in southeastern Washington State, from 1968 through 1980. The Hanford Site is in this area and serves as a major employer. In addition, various agriculturally and chemically related activities are in the area. Hospital and vital records were used to identify 454 malformation cases among 23,319 births; this yielded a malformation rate of 19.6 per 1,000 births, a rate similar to those reported in other studies. The rates of specific malformations ascertained during the first year of life were compared with combined rates from the states of Washington, Oregon, and Idaho from the Birth Defects Monitoring Program. Among defects that would be expected to be comparably ascertained, a statistically significant elevated rate of neural tube defects was observed (1.72 per 1,000 births vs. 0.99 per 1,000). Rates of cleft lip were significantly lower in Benton and Franklin counties than in the Birth Defects Monitoring Program (0.59 per 1,000 vs. 1.17 per 1,000). For congenital heart defects, pyloric stenosis, and Down syndrome, which are often not diagnosed in the newborn period, Birth Defects Monitoring Program data did not offer appropriate comparisons. The rates of these defects did not appear to be elevated in relation to rates found in other relevant populations. When rates of neural tube defects were compared with those in populations other than the Birth Defects Monitoring Program, the Benton and Franklin county rates were still considered to be elevated. The increased bicounty rate cannot be explained by employment of the parents at Hanford or by the impact of plant emissions on the local population.