Comparative risk and impact assessment for occupational and environmental health

In the quantification of burdens of diseases, QALY (quality-adjusted life year) or DALY (disability-adjusted life year) have been used for comparative assessment of population health. By adjusting the survival function with the mean of quality of life (QOL) at every time point t and summing up yearly throughout lifetime, we obtained the quality-adjusted life expectancy (QALE) with the unit of QALY: QALE = ∫E[Qol(t|x_i)]S(t|x_i)dt Three environmental health issues were empirically assessed as examples: the contamination of underground water by chlorinated hydrocarbons from an electronics factory; the enforcement of helmet law in Taipei city; and occupational policies for protection of offspring of female lead workers. The likelihoods and expected numbers of new cases with liver cancer, head injury, or mentally impaired offspring born to mothers of lead workers were estimated, and these were then multiplied by the quality-adjusted life expectancy lost per case. The results showed that the ground water pollution produced a potential loss of 78 QALM (quality-adjusted life month) for the 1000 people in the downstream community. The enforcement of helmet law in Taipei would save 6240 QALY annually. The expected utility loss of the babies born to female lead workers was about 216 QALY. If the QOL was measured by psychometry, it could be applied in clinical outcome evaluation. If it was extended to consider the cost of illness, the financial burden to the National Health Insurance could be estimated. We conclude that this is a feasible method for comparative health risk/impact assessment for public health and clinical policy decisions.