| This analytic data file set consists of five analytic files that support a prevalence study by Lowell Sever, et al., of congenital malformations among births in two counties adjacent to the Hanford Site during 1958 to 1980, published in the American Journal of Epidemiology in 1988. |
| The purpose of this study was to investigate the prevalence of congenital malformations among births in two southeastern Washington State counties where the Hanford Nuclear Site is a major employer. Various agriculturally and chemically related activities take place in this area as well. The rates of specific malformations ascertained during the first year of life were compared with combined rates from the Birth Defects Monitoring Program (BDMP) for the states of Washington, Oregon and Idaho. Among defects that would be expected to be comparably ascertained, a statistically significant elevated rate of neural tube defects was observed in the two counties, while rates of cleft lip were significantly lower. For congenital heart defects, pyloric stenosis and Down syndrome (defects often not diagnosed during the newborn period), BDMP data did not offer appropriate comparisons. However, 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 populations other than those in the BDMP, the bicounty rates were still considered elevated. The increased rate cannot be explained by employment of the parents at Hanford or by the impact of Hanford plant emissions on the local population. |
| The HFMPVA02 data file set is comprised of five analytic files with information on 454 malformation cases. The first file, HFMPVA02_d1 (MALPVA_1), contains demographic data for the parents and the reproductive history of the mother. The second file, HFMPVA02_d2 (MALPVA_2), contains birth data for the infant. The third file, HFMPVA02_d3 (MALPVA_3), contains malformation data and additional medical data for the infant and mother. If the parents worked at Hanford prior to the infant's date of birth, the fourth file, HFMPVA02_d4 (MALPVA_4), contains employment data, and the fifth file, HFMPVA02_d5 (MALPVA_5), contains radiation exposure data. There is one record in each file for each of the cases. |
| The population at risk consists of 23,076 live births and 243 fetal deaths occurring in three of the bi-county hospitals from the beginning of the study in 1968 through the end of the study in 1980. Thus, the denominator for prevalence rates is 23,319. A total of 454 malformation cases were identified, for a congenital malformation rate in the newborn population of 19.6 per 1,000, or about 2% of all births. For the bi-county general public, a maximally exposed individual could not have received more than 10 millisieverts (mSv) from Hanford nuclear activities during 1957 to 1984. This is about one-third of the exposure received from natural background over the same period. At the time of this study, more than 65,000 individuals had been employed at Hanford since it began operations in 1944, and about 15,000 of these people were still employed there. On the basis of a companion case-control study (HFMCCA02), it is estimated that 23% of all infants born during the 1968 to 1980 study period would have one or more parents employed at Hanford, and about 6% of these infants would have a parent with cumulative Hanford ionizing radiation exposure exceeding 10 millisieverts. |
| Radiation exposure data routinely collected at Hanford include the doses from external sources to the whole body, the skin of the whole body, and the extremities, for each employee working with or near radiation sources. Dose estimates, presented in units of millisieverts, were obtained primarily from personal dosimeter measurements. A sievert is numerically equivalent to the absorbed dose in gray multiplied by a quality factor expressing the biological effectiveness of the radiation type. Factors of 10 for fast neutrons, 3 for slow neutrons, and 1 for photons were used to convert external exposure measurements to dose estimates. Workers who are considered at risk for internal depositions also undergo routine bioassays and in vivo tests to determine such radiation exposure. |
