Hormone replacement therapies have received attention in both women and men and may have implications for bone, muscle, skin, and other organ systems if successfully applied on a widespread basis. However, their adverse effects have not been fully evaluated.

Skin Aging

A wide variety of occupationally related skin conditions have been described, with many pathogenic mechanisms (Peate, 2002). Skin aging may be thought of as intrinsic and extrinsic, with many genetic and environmental determinants and altered cellular and biochemical activity (Jenkins, 2002). A particularly important cause of extrinsic skin aging is related to sun exposure, which in some circumstances may have occupational dimensions. This in turn leads to wrinkling, blotching, dryness, and leathering (Schober-Flores, 2001), as well as important skin cancers. Photo-aged skin, of whatever origin, is anatomically thinner and acquires increased permeability, becoming at least potentially a poorer barrier to chemical and related exposures (Elias and Ghadially, 2002). This may have implications for the rates of absorption of occupationally associated chemical and biological agents, possibly exacerbated by occupations where major or minor skin injuries occur, although little work has been done in this area. Age-related decreases in the rate of skin wound healing may also be important in certain workplaces, although there is likely to be an important role for comorbid conditions in wound healing (Thomas, 2001). As research progresses, it may be possible to add skin topics to health promotional programs in occupational settings.

Metabolism

Many changes in intermediary and xenobiotic metabolism occur with age, and these undoubtedly have great import for the older worker. For example, with increasing age, mitochondria produce less adenosine triphosphate (ATP), the body’s main metabolic source of energy, and higher levels of reactive oxygen species, which have been related to several human diseases as well as DNA instability (Wei and Lee, 2002). The aging liver is characterized by a reduction in oxidative functions, including oxidative drug metabolism (Jansen, 2002). However, the impact of age on pharmacodynamics and pharmacokinetics may be difficult to predict, suggesting that more studies among elders are needed (Klotz, 1998). These observations and others have implications for the general determination of whether the metabolism, toxicology, and disposition of workplace chemical exposures differ between older and younger workers as well as for understanding the impact of polypharmacy (common among older persons) on organ function



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