The hfmpva02 data file set is comprised of five analytic files with information on 454 malformation cases. The first file (MALPVA_1) contains demographic data for the parents and the reproductive history of the mother. The second file (MALPVA_2) contains birth data for the infant. The third file (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 (MALPVA_4) contains employment data, and the fifth file (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 bicounty 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. 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 bicounty general public, a maximally exposed individual could not have received more than 10 millisieverts (mSv) from Hanford nuclear activities during 1957-1984. This is about 1/3 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 1968-1980 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 includes 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.