What Is a "Reference Dose"?
27 Mar 2006 in Regulatory Science, Glossary
Neutral Source has been covering a recent report of EPA's Children's Health Protection Advisory Committee concerning the level of perchlorate exposure the Agency should consider acceptable.
EPA’s definition of the reference dose is a complex term of art, however. According to EPA, the reference dose is:
There are a number of terms and phrases in this definition that may not be clear. In particular, any dose less than or equal to the reference dose “is likely to be without an appreciable risk of deleterious effects during a lifetime.” In other words, doses at or below the reference dose are “safe.” But the definition does not say that doses above the reference dose are “unsafe.” It’s silent about that.an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily oral exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. It can be derived from a NOAEL, LOAEL, or benchmark dose, with uncertainty factors generally applied to reflect limitations of the data used.
The definition also says that “sensitive subgroups” are covered. In other words, doses at or below the reference dose are “safe” for practically everyone. US EPA's Children's Health Protection Advisory Committee appears to be saying that EPA’s reference is unsafe for infants—in other words, EPA’s reference dose does not meet the Agency’s definition of the reference dose.
EPA’s reference dose for perchlorate was derived by a committee of the National Academy of Sciences. We will discuss that connection in a later post.
