Toxicology of Industrial Compounds

Figure 20.9 Fertility
delivered and examined for abnormalities according to procedures used in
embryotoxicity studies. (Note that this study is almost identical to a
modified OECD 421 study.) Combination with the ICH developmental
toxicity study provides the equivalent of a two generation and
embryotoxicity study.
Interpretation of studies
A.K.PALMER 297
For regulatory agencies, one of the purposes of these tests is to gather
information for labelling. By common consensus, a substance is labelled as
a reproductive toxicant only if it induces effects at dosages below those
causing systemic toxicity. Such labelling, however, can be very misleading
especially with industrial chemicals. Even if the animal species can be
shown to be a good surrogate for humans by means of kinetic and other
studies, it is necessary to take into account the relationship between
exposures causing effects and those likely to be encountered by humans.
For example, a material can be labelled as a reproductive toxicant but
present little or no real risk to humans because the effects are induced at
exposures well in excess of those encountered by humans (Figure 20.10).
Conversely, a substance not labelled as a reproductive toxicant could cause
reproductive effects in humans if these are induced at exposures
encountered by humans. In other words toxicity is relative, a matter of
dosage and situation. Labelling without reference to exposures is
incomplete.