Chemical Sensitivities: The Role of Adaptation (Premium)

WILLIAM REA, MD

This article is a follow up piece to Chemical Sensitivities: Total Load. Hypersensitivity to chemicals is a growing phenomenon. A lack of government oversight on the production of chemicals, poor reporting systems for reactions to chemicals, and a misunderstanding of the biological basis for multiple chemical sensitivity (MCS) are partly to blame for an upsurge in this medical problem.

Adaptation

Adaptation is an acute survival mechanism which apparently allows an individual to “get used to” an acute toxic exposure in order initially to survive it. Adaptation involves a change in homeostasis (steady state) brought on by exposure to pollutants in the internal or external environment. Body function accommodates this exposure by adjusting to a new set point with induction and increased output of enzyme detoxification systems and immune system enhancement within a physiologic range. Adaptation can occur in any organ or tissue that has been affected by pollutant exposure. Further, pollutant load may increase in all organs or just one.

Over time, adaptation that accompanies continued exposure to toxic substances can result in a long-term decrease in efficient functioning that can then lead to diminished longevity. Because an individual is unable to recognize the acute effects of toxic exposure during adaptation (masking- acute toxicological tolerance), he may inadvertently allow repeated exposures during which pollutants continue to enter and accumulate in his body. These substances may gradually contribute to an increased total body load and depletion of nutrient fuels as his body tries to counteract this build-up. Finally, depressed function occurs followed by end-organ failure.