2.2. Health of semiconductor workers
The occupational health and safety of workers on fabrication lines is of particular concern. Because semiconductor production is a light manufacturing industry, the worker illness and injuries that occur day-to-day are not as severe as in heavy industries. The main health concern for the industry is whether long-term chemical exposure increases rates of birth defects and cancer. The extent of risk to workers is still unclear; connections between long-term exposure and illness are notoriously difficult to prove (or disprove), and this is especially true for the semiconductor industry, due to the complexity of its chemical mixes and frequent changes in processes. Epidemiological evidence points to potential negative effects on reproductive health: three studies indicated that female fabrication workers displayed an elevated incidence of miscarriages [6], [7] and [8]. This increased miscarriage rate was correlated, though not conclusively, with exposure to ethylene glycol compounds (used as a photoresist solvent). Many firms reportedly stopped using these chemicals as a result of these studies.
Elevated miscarriage rates are considered a warning signal of possible elevated rates of birth defects and cancers. IBM and National Semiconductor have been facing a barrage of lawsuits from former workers claiming that chemical exposure led to birth defects or cancer. Most cases are still pending, but those completed were settled out of court for undisclosed compensation and no admission of guilt [9]. There is no scientific evidence either supporting or denying workers' claims. Only one publicly available epidemiological study investigating birth defects and cancers in the semiconductor industry currently exists. This study, carried out by health authorities in the United Kingdom, found that cancer rates for workers at a Scottish plant were comparable to the average population, though there were noticeable distinctions in the patterns of cancer that developed. Plant workers showed higher incidences of lung, stomach, breast, and brain cancer. This work has been criticized, however, due to its small sample size (71 deaths) and lack of distinction made between different work duties at the plant [10]. There has been a long-standing need for a serious study of cancer and birth defects in the semiconductor industry, but so far firms and governments have shown little initiative to carry out such work [11].