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Table 1 US approaches to account for human variability in derivation of reference values for risk assessment

From: Current practice and recommendations for advancing how human variability and susceptibility are considered in chemical risk assessment

Approach

Intended Use

Method

Default adjustment factor (AF)

Adjust for total intra-species variability.

AFH = 10.

Default subfactor approach

Adjust for intra-species variability in metabolism (TK) and tissue response (TD).

AFH ≤ 10

(usually 3X each for AFH-TK and AFH-TD).

Chemical-specific adjustment factor (CSAF) or data-derived extrapolation factor (DDEF)

Adjust for chemical-specific intra-species differences in metabolism (TK) and tissue response (TD).

AFH-TK and AFH-TD based on case-by-case TK/TD data.

  1. AFH Intra-species human variability adjustment factor, AFH-TK Intra-species human variability adjustment subfactor for variation in kinetic chemical metabolism, AFH-TD Intra-species human variability adjustment subfactor for variation in target tissue response
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Environmental Health

ISSN: 1476-069X