Sensitivity of older persons to hazardous substances

Status:

completed 12/2008

Aims:

Owing to the demographic shift, which is a result of higher life expectancy with a simultaneous decline in the birth rate, the proportion of older people in the German population will continue to increase in the future. The demographic shift, the statutory increase in the pensionable age and financial penalties for early retirement will also cause the average age of companies' workforces to rise further. Owing to these structural changes, older people are increasingly emerging as a target group for occupational safety and health. In the context of comprehensive preventive healthcare measures for older people, consideration must also be given to the possible influence of ageing processes upon these persons' susceptibility in the event of exposure to hazardous substances. A literature survey was performed with the objective of compiling findings concerning the possible influences of age-related physiological changes upon susceptibility to hazardous substances and of analysing the relevance of these findings to the situation of older employees at workplaces involving exposure to hazardous substances.

Activities/Methods:

By the use of relevant search terms, searches were performed on the Internet (for example in the MEDLINE database), in particular for more recent, relevant original work and review articles. The findings were compiled and analysed with regard to their relevance to the situation of older employees.

Results:

Compared to industrial chemicals, pharmaceuticals have been studied more comprehensively with regard to their age-related behaviour in the human body. Findings relating to pharmaceuticals enable conclusions to be drawn regarding the age-related effects of other foreign substances upon the human body. At the same time, epidemiological studies into the effect of substances of general relevance to the environment, particularly particulates, identified older population groups, whose age was generally defined as at least 65, as being subpopulations facing an elevated morbidity and mortality risk.

Ageing processes begin before a calendar age of 65, however. These processes differ widely between individuals, and may be linked, particularly in their advanced stages, to changes in sensitivity to hazardous substances, as a result for example of changes in substance absorption, in distribution, and in the metabolism and in elimination; a decrease in elimination through the kidneys constitutes one of the most important factors. Declining cardiac and pulmonary function and/or age-related diseases of these organs were associated with an increased sensitivity to air pollution. Since the physiological capacity to compensate for exogenic and endogenic stresses declines in old age, older people are substantially less able to attenuate the toxic effects of chemicals in comparison with younger people. At the same time, evidence suggests that in old age, sensitivity to hazardous substances ? such as certain allergens and compounds which are activated by liver enzymes ? may under some circumstances be reduced.

Owing to the heterogeneity of the ageing processes and the complex interaction between the multiple influences, which may be either reinforcing or attenuating in their effects, it is difficult to quantify the potential changes in sensitivity with any precision in terms of the calendar age of an older person. However, the findings available to date cast doubt upon whether such processes in the age band of healthy older employees (aged 45-65) are on average already so pronounced that they lead to substantially higher risks in comparison with the age band of younger adults. The data found do not therefore justify occupational safety and health measures for older employees relating to hazardous substances that are different to those for younger employees. In specific cases however, diseases which are more prevalent in old age (such as liver and kidney disease, pulmonary and cardiovascular diseases, diabetes mellitus) may increase the sensitivity to certain substances.

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