Maximum acceptable concentration (MAC)


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Terms & Synonyms

Official WHO Definition

Maximum acceptable concentrations (MACs) have been established for certain substances that are known or suspected to cause adverse effects on health.

Other Definitions


Interpretations and Explanations

They have been derived to safeguard health on the basis of lifelong consumption. To the extent possible, the use of drinking water for all usual domestic purposes, including personal hygiene, has been considered in the derivation of the guidelines. However, water of higher quality may be required for some special purposes, including renal dialysis. Drinking water that continually contains a substance at levels greater than the MAC will contribute significantly to consumers' exposure to this substances and may, in some instances, be capable of inducing deleterious effects on health. However, short-term excursions above the MAC do not necessarily mean that the water constitutes an undue risk to health. The amount by which, and the period for which, the MAC can be exceeded without posing a health risk must be assessed by taking into account the toxicity of the substance involved. When the MAC for a contaminant is exceeded, however, the minimum action required is immediate resampling. If the MAC continues to be exceeded, the authorities responsible for public health should be consulted concerning appropriate corrective action.


Health Canada

WHO Lexicon page (translations and examples)

See also

External Resources


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