Human exposures to methomyl fall into three toxicity categories de fi ned by the
US EPA that depend on the route of exposure: I, oral exposure (highly toxic); II,
inhalation (moderately toxic); and III, dermal exposure (slightly toxic; US EPA
1998b ) . Furthermore, methomyl is considered to be highly toxic to mammals, fi sh
and aquatic invertebrates (Farre et al. 2002 ) . To illustrate, the acute oral LC 50 given
for rats was 17–45 mg/kg (Mahgoub and El-Medany 2001 ) , the LC 50 values for
bluegill sun fi sh and rainbow trout were 0.9–3.4 mg/L, and the LC 50 values for
Daphnia magna were from 0.022 to 0.026 mg/L (Yi et al. 2006 ; Periera et al. 2009 ) .
Because methomyl’s water solubility and toxicity to non-targeted aquatic organisms
is high (Table 1 ), concerns exist for its potential impact on surface water, groundwater,
and aquatic organisms. Therefore, the most up to date information may be useful