Document JJ0mexdBmwy1mBrODXQ9n4986

390 Annals New York Academy of Sciences Table 2 Aob Distribution of Household Contacts and Controls at Time of X-Ray Examination Age (yrs.) 20-29 30-39 40-49 50-59 60-69 70+ Total Number of Household Contacts* 54 (8%) 188 (28%) 196(29%) 144(21%) 68(10%) 29 (4%) 679 Number of Controls! 30 (9%) 59 (18%) 80 (25%) 83 (26%) 51(16%) 22 (7%) 325 Mean age of household contacts 45.7 12 yrs. fMean age of controls 48.6 14 yrs. Altogether nearly one-third of those examined were under the age of 40. Two-thirds of individuals had already exceeded 30 years from onset of initial asbestos exposure. Information is not available on the dimensions of the asbestos contamination which remained in the house after the worker changed employment. The prevalence of radiographic abnormalities among the survey participant groups is summarized in Table 4. The control population had a 5% overall prevalence of radiographic abnormalities. Individuals who resided in a household after the index worker's employment period had the second lowest prevalence of abnormalities (12%) followed by persons in residence (35%) during the index worker's employment. As would be expected, the highest prevalence of abnormalities (45%) was among the household residents with reported personal occupational asbestos exposure. Pleural abnormalities were more prevalent than parenchymal small opacities. When the comparative prevalence of the various types of asbestos-associated radiographic abnormalities was analyzed, it was found that pleural abnormalities were the most prominent (Table 5). Pleural calcifications were present in 8% of the household contacts and were seen in none of the controls. Pleural thickening was present on 19% of the household contact radiographs and only 1% of the control chest x-rays. Overall, 239 (35%) of the household contacts had one or more abnormalities present compared to 15 (5%) of the control group. These radiographic abnormalities Table 3 Distribution of Household Contacts by Duration of Exposure and Year of Onset of 1st Exposure Year of First Exposure 1941-46 1946-50 1950-55 Total Total Examined 436 113 129 678 <1 Year 124 29 40 193 (28%) Duration of Exposure 1-5 Years 5-10 Years 246 32 68 16 89 -- 403(59%) 48 (7%) 10+ Years 34 -- -- 34 (5%)