The phrase "classifiable to" is correct and can be used in written English.
It means that something can be categorized or grouped into a certain class or category. Example: The new species of orchid discovered in the rainforest is classifiable to the genus "Dendrobium", based on its physical characteristics and DNA analysis.
On the other hand, IARC downgraded the classification of di 2-ethylhexyl phthalate (di 2-ethylhexyl phthalate"not classifiable as to its carcinogenicity to humans" (IARC 2000).
An IARC working group recently downgraded DEHP to "not classifiable as to its carcinogenicity to humans" because they concluded that DEHP produces liver tumors in rats and mice by a mechanism involving peroxisome proliferation, which they considered to be not relevant to humans.
Combination of these two partial evaluations yields a preliminary default evaluation that the agent is one of the following: group 1, carcinogenic to humans; group 2A, probably carcinogenic to humans; group 2B, possibly carcinogenic to humans; group 3, not classifiable as to its carcinogenicity to humans; or group 4, probably not carcinogenic to humans.
These two partial evaluations are combined into a preliminary default evaluation that the agent is "carcinogenic to humans" (group 1), "probably carcinogenic to humans" (group 2A), "possibly carcinogenic to humans" (group 2B), "not classifiable as to its carcinogenicity to humans" (group 3), or "probably not carcinogenic to humans" (group 4).
Because epidemiological studies of HQ and 1,4-benzoquinone have never demonstrated carcinogenicity in humans, the International Agency for Research on Cancer (IARC) assigned their carcinogenic risk to humans as group 3: not classifiable as to carcinogenicity to humans (IARC 2011).
However, the IARC categorizes permethrin in group 3: not classifiable as to carcinogenicity to humans (IARC 1991).
It is important to note that the evaluation of an agent as not classifiable as to its carcinogenicity to humans is not a determination of safety, with respect to both cancer and effects other than cancer.
The International Agency for Research on Cancer, part of the World Health Organization and dedicated to identifying cancer causes, said personal hair dye is "not classifiable as to its carcinogenicity to humans," based on a lack of evidence from studies in people.
As per International Agency for Research on Cancer evaluation, inorganic Pb compounds are probably carcinogenic to humans (Group 2A), whereas organic lead compounds are not classifiable as to their carcinogenicity to humans (Group 3) [ 126].
Owing to a lack of data, some of the other pesticides that were detected are not classifiable as to their carcinogenicity to humans (International Agency for Research on Cancer, 1991).
