| This analytic data file set consists of five analytic files used to support a case-control study by Lowell Sever, et al. of congenital malformations among births in two counties adjacent to the Hanford Site during 1957 to 1980, published in the American Journal of Epidemiology in 1988. |
| The purpose of the study was to investigate the association of parental occupational exposure to low-level external whole-body penetrating ionizing radiation and risk of congenital malformations in their offspring. Cases and controls were ascertained from births in two counties in southeastern Washington State, where the Hanford Site has been a major employer. Twelve specific malformation types were analyzed for evidence of association with employment of the parents at Hanford and with occupational exposure to ionizing radiation. Two defects, congenital dislocation of the hip and tracheoesophageal fistula, showed statistically significant associations with employment of the parents at Hanford but not with parental radiation exposure. Neural tube defects showed a significant association with parental preconception exposure, on the basis of a small number of cases. Eleven other defects, including Down syndrome, for which an association with radiation was considered most likely, showed no evidence of such an association. When all malformations were analyzed as a group, there was no evidence of an association with employment of the parents at Hanford but the relation of parental exposure to radiation before conception was in the positive direction. Given the number of statistical tests conducted, some or all of the observed positive correlations are likely to represent false positive findings. In view of strong contradictory evidence, based on no demonstrated effects in genetic studies of atomic bomb survivors in Hiroshima and Nagasaki, it is unlikely that these correlations result from a cause-and-effect association with parental radiation exposure. |
| The HFMCCA02 data file set is comprised of five analytic files with information on 672 malformation cases and 978 matched controls. The first file, HFMCCA02_d1 (MALCCA_1), contains demographic data for the parents and the reproductive history of the mother. The second file, HFMCCA02_d2 (MALCCA_2), contains birth data for the infant. The third file, HFMCCA02_d3 (MALCCA_3), contains malformation data for cases 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, HFMCCA02_d4 (MALCCA_4), contains employment data, and the fifth file, HFMCCA02_d5 (MALCCA_5), contains radiation exposure data. There is one record in each file for each of the cases and controls. |
| A unique feature of this study was the linking of quantitative individual measurement of external radiation exposures of Hanford employees and the disease outcome, congenital malformations. The population at risk, from which cases and controls were ascertained, consists of live births and fetal deaths occurring in three local hospitals during 1957 through 1980, the study ending date. Of the 672 cases, 146 fathers and 48 mothers were employed at Hanford prior to conception. Twenty-two mothers of cases were employed at Hanford during gestation. Of these cases, 125 fathers and 28 mothers had positive recorded doses prior to conception. Only one mother of a case received more than 1 millisievert (mSv) during gestation. Information on internal radionuclide depositions was also obtained. However, only one father of a case had evidence of a deposition, and it was determined to be less than 1% of the applicable maximum permissible body burden. |
| 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. Because exposure to the gonads was the primary interest of this study, analyses were limited to consideration of exposure to external whole-body penetrating radiation. 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. |
