An alternative method for verifying the correct prescribing of sick leave would be to just study diseases that occur most often. This would focus on those workers who had recurrent absences due to sick leave.

Most of mortality studies among steelworkers pointed out an increased frequency on cancer mortality, above all by lung cancer, and, in a lower proportion, by cancers of digestive and genitourinary systems. In Spain mortality rates are not published by occupation and economic activity to contrast these observations. It was carried out a proportionate mortality study among active or retired workers from an steel mill, Altos Hornos de Vizcaya, died from 1986 to 1993, to make a preliminary death risk assessment associated with job in the steel industry. A sample of 1553 men was drawn from the mortality register of a private Insurance Company. Death causes within the sample and in general population of the Autonomous Community of the Basque Country were compared using a proportionate analysis. Mortality odds ratios (OR) were also computed. The results show an excess of cancer mortality (OR = 1.26, IC: 1.11-1.42), stomach cancer (OR = 1.50, IC: 1.14-1.98) and renal cancer (OR = 1.89; IC: 1.14-3.14) as it has been stated by other authors. It has not been found an increased mortality risk from lung cancer (OR = 1.13, IC: 0.91-1.40), bladder cancer (OR = 1.13, IC: 0.74-1.72) and chronic respiratory disease (OR = 0.94, IC: 0.73-1.20). There is also an excess of liver cancer (OR = 1.56, IC: 1.06-2.28) and cancer of non specified location (OR = 1.85, IC: 1.45-2.36). This can be due to classification bias that affects the study. On the other hand, these and other selection bias, discussed in this paper, could underestimate the lung cancer mortality. We can not conclude that, among the workers of the study, the mortality from several kind of cancer is not associated to occupational exposure. Furthermore, this excess of stomach and kidney cancer mortality may lead us to pose the hypothesis of cause-effect relationship with some not well identified carcinogens present at the steel working place.

Six years after having solved the problem near to the factory and storage of HCH, there was no significantly higher levels of HCH, after adjustment for age.