Cooper W C, Sargent E N
J Occup Med. 1984 Jun;26(6):456-60. doi: 10.1097/00043764-198406000-00019.
Chest roentgenograms of 473 employees of a California diatomite plant were reviewed as part of periodic reevaluation of the efficacy of the dust control program. The plant's processing of diatomite included flux-calcination, which provided opportunities for exposure to cristobalite. The films examined were those of workers with at least five years of service. Only 11 films were interpreted as showing changes consistent with pneumoconiosis, i.e., small opacities of profusion categorized as 1/1 or greater. Only six were classified as 1/2 or more. All who developed categories 1/1 or higher during their employment had more than 25 years of service. No large opacities were reported. The low prevalence of abnormalities and the absence of definite pneumoconiosis in employees with fewer than 25 years of service was in striking contrast with findings in 1953. At that time more than 25% of those with five or more years of employment had roentgenographic evidence of pneumoconiosis and over 10% had confluent changes producing large opacities.
作为对粉尘控制项目成效进行定期重新评估的一部分，对加利福尼亚一家硅藻土工厂的473名员工的胸部X光片进行了复查。该工厂对硅藻土的加工包括助熔煅烧，这使得工人有接触方石英的机会。所检查的X光片来自至少工作五年的工人。只有11张X光片被解读为显示出与尘肺病相符的变化，即小阴影密集度分类为1/1或更高。只有6张被分类为1/2或更高。所有在工作期间出现1/1或更高分类的人都有超过25年的工作年限。未报告有大阴影。工作年限少于25年的员工中异常情况的低发生率以及明确尘肺病的缺失，与1953年的调查结果形成了鲜明对比。当时，工作五年或更长时间的员工中，超过25%有尘肺病的X光证据，超过10%有融合性变化产生大阴影。
