7200

• UCREFRP Catalog Number: 7200
• Author: Odenkirchen, E. W. and R. Eisler.
• Title: Chlorpyrifos Hazards to Fish, Wildlife, and Invertebrates
• USFW Year: 1988.
• USFW - Doc Type: A Synoptic Review.
• Copyright Material: NO

Bioconcentration of chlorpyrifos from the medium varied substantially
among five species of fishes, but generally paralleled ambient levels of
chlorpyrifos (Table 4). Increases in bioconcentration factors (BCF) in
chlorpyrifos-exposed teleosts may be associated with three variables:
increased metabolic rate, as indicated by hyperventilation, hyperactivity, and
decreased growth; increased bioavailability of chlorpyrifos as a result of
solvent-induced supersaturation or increased food availability; and decreased
depuration rates due to possible physiological dysfunction (Goodman et al.
1985a, b; Hansen et al. 1986). At high BCFs, adverse effects on growth and
survival were observed in sheepshead minnow (Cyprinodon variegatus) by Cripe
et al. (1986) and in Gulf toadfish (Opsanus beta) by Hansyn et al. (1986).
Chlorpyrifos is excreted rapidly from fish; the estimated Tb- is 8.7 hours,
and equilibration occurs with the surrounding medium in 24 t6 72 hours (Smith
et al. 1966; Blau and Neely 1975; Marshall and Roberts 1978). No detectable
chlorpyrifos residues were found after 12 days in 10 species of estuarine
invertebrates--including oligochaete annelids, molluscs, and crustaceans--
after treatment with 0.046 kg chlorpyrifos/ha (Marganian and Wall 1972).

BIRDS AND MAMMALS

Signs of chlorpyrifos intoxication, as summarized by Hudson et al.
(1984), include excessive blinking, hypoactivity, hyperexcitability, excessive
drinking, muscular incoordination, rapid breathing, muscular weakness,
tremors, piloerection (mammals) or fluffed feathers (birds), salivation,
lacrimation, diarrhea, excessive urination, prostration, loss of righting
reflex, spasms, tetany, coma, and convulsions.. Death usually occurs between I
hour and 9 days after exposure. Chlorpyrifos oxon (0,0-diethyl-0-(3,5,6-
trichloro-2-pyridyl) phosphate) is the active oxygen analog of chlorpyrifos
and is probably responsible for most of the anticholinesterase mode of action
of chlorpyrifos; the ox on is extensively and rapidly detoxified in mammalian
liver via enzymatic hydrolysis by at least two microsomal esterases (Sultatos
and Murphy 1983). Significant accumulations of chlorpyrifos were not detected
in domestic turkeys (Meleagris gallopavo) and chickens. In birds kept in pens
on soil treated with 4.5 to 9.0 kg active ingredients chlorpyrifos/ha, tissue
residues were 0.16 mg/kg after I week; these decreased thereafter, although
birds remained on the treated soil (Kenaga 1974).

LD-50 val'ues, based on a single oral dose, ranged from 5 to 157 mg
chlorpyrifos/kg body weight (BW) in birds, and from 151 to 1,000 in mammals;
however, 7 of 14 avian species had reported LD-50 values of <25.0 mg/kg BW
(Table 5). Many species of birds that survived chlorpyrifos poisoning showed
gross pathological changes (Tucker and Crabtree 1970); furthermore, the slope
of the acute dose-response curve was low (Hudson et al. 1984). These findings
suggested that decreasing dosage levels did not produce proportional decreases
in response, and indicated a reduced safety margin for chlorpyrifos owing to
mortalities that occur frequently at levels much lower than the calculated
LD-50 values (Hudson et al. 1984); however, more research is needed to verify
this trend.

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