Environmental Engineering Reference
In-Depth Information
5.1
Acute Toxicity Studies
Oral gavage and dietary studies have been conducted to determine the acute effects
of CPY on birds (Table
4
). Data on toxicity of CPY to birds were reviewed previ-
ously (Solomon et al.
2001
) and in the sections that follow, only studies that have
been conducted since that review are discussed.
Hubbard and Beavers (
2008
) administered CPY by oral gavage at 21.6 mg ai
kg
−1
bwt to 19-wk old northern bobwhite (
C. virginianus
) using corn oil as a vehicle
and observed signs of toxicity (Hubbard and Beavers
2008
). The effects included a
ruffl ed appearance and lethargy. Signs of toxicity were more prevalent and occurred
sooner at higher doses. Reduced consumption of food was observed at doses
≥
36 mg ai kg
−1
bwt. The acute oral 14-d LD
50
was >60 mg ai kg
−1
bwt, as only 30%
mortality occurred at this dose, the largest tested. The no-mortality dose was 36 mg
ai kg
−1
bwt and the NOEL was 13 mg ai kg
−1
bwt.
The acute oral toxicity of Lorsban 50W was determined by exposing northern
bobwhite (
C. virginianus
) (Kaczor and Miller
2000
). Twenty-two-wk old birds were
dosed once with Lorsban 50W (50.5% purity) and observed for 14-d. Food con-
sumption, body weight, signs of toxicity, and lethality were monitored throughout
the observation period. In the group fed the greatest dose (121 mg ai kg
−1
bwt), all
birds died within 24 h of dosing. During the fi rst day or two following dosing, con-
sumption of food by birds exposed to CPY was less that of the controls. However,
rates of food consumption quickly returned to those of control birds and, as a result,
there was no signifi cant decrease in body weight over the study period for any of the
treatment groups. The most prevalent sign of toxicity was lethality. The only other
observed sign of toxicity was lethargy and it usually preceded lethality. Necropsies
of dead birds revealed gaseous intestines. The LD
50
was 35.9 mg ai kg
−1
bwt, the
NOEC was 7.6 mg ai kg
−1
bwt and the LOEC was 15.2 mg ai kg
−1
bwt.
In other studies, the toxicity of CPY in a variety of formulations was evaluated.
These formulations included Lorsban 2.5P (2.48% ai, Brewer et al.
2000b
), Lorsban
10.5 LEE (10.5% ai, Brewer et al.
2000a
), GF-1668 (18.7% ai, Gallagher and
Beavers
2006
), and Lorsban Advanced (41.1% ai, Hubbard and Beavers
2008
).
The lowest LD
50
from these studies was 12.6 mg ai kg
−1
bwt (Brewer et al.
2000a
)
and the smallest NOEL was <4 mg ai kg
−1
bwt (Hubbard and Beavers
2008
).
To determine the importance of duration of acute exposure on a daily basis,
25-wk old northern bobwhite (
C. virginianus
) were pre-conditioned to feed during
either a 1- or 8-h period each day (Gallagher and Beavers
2007
). Following the
pre-conditioning period, the birds were offered food treated with CPY for either 1
or 8 h for 1-d. The birds were observed for 7-d after treatment. Rate of food con-
sumption and body mass decreased with increasing dietary concentration of CPY
in both treatment groups. Greater toxicity was observed in the group feeding for
only 1 h each day. This result suggests that birds being exposed over an 8-h period
had longer to metabolize and detoxify CPY. LD
50
values were 75 mg ai kg
−1
bwt for
birds receiving their total dose in 1 h and 116 mg ai kg
−1
bwt for those receiving the
dose over an 8-h period. LC
50
values were 3,697 and 6,986 mg ai kg
−1
diet for birds
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