Page 599 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

564 SECTION | VII Herbicides and Fungicides

VetBooks.ir male reproductive toxicity of glyphosate is due to the measures such as cool baths or sponging and keeping the
animal in a shaded area are advocated. Intravenous
inhibition of a StAR protein and an aromatase enzyme,
administration of large doses of sodium bicarbonate (in
which caused an in vitro reduction in testosterone and
estradiol synthesis. The study further suggested that com- carnivores) solutions, parenteral vitamin A, and intense
mercial formulation of glyphosate (glyphosate Roundup oxygen therapy, where possible, may be useful. If the her-
Transorb, Monsanto) is a potent endocrine disruptor bicide is ingested and the animal is alert, an emetic should
in vivo because it caused disturbances in the reproductive be administered; if the animal is depressed, gastric lavage
development of rats when the exposure was performed should be performed. Treatment with activated charcoal
during the puberty period (Romano et al., 2010). From should follow. Dextrose saline infusions in combination
various experimental studies, it has been concluded that with diuretics and tranquilizers (not barbiturates) are very
herbicides can disturb reproduction and developmental useful. In ruminants, for methemoglobinemia, methylene
processes of both males and females through endocrine blue solution and administration of ascorbic acid are
signals in organisms indirectly exposed during prenatal or useful (Lorgue et al., 1996).
early postnatal life. Such effects during fetal development
may be permanent and irreversible.
According to one estimate, eight herbicides (2,4-D, CONCLUDING REMARKS AND FUTURE
2,4,5-T, alachlor, amitrole, atrazine, metribuzin, trifluralin DIRECTIONS
and nitrofen) were identified as endocrine disruptors.
Herbicides are routinely used to control noxious plants.
Most of these were identified accidentally rather than as a
Most of these chemicals, particularly the synthetic organic
result of an exhaustive screening process (Pocar et al.,
herbicides, are quite selective for specific plants and have
2003).
low toxicity for mammals; other less selective compounds
(e.g., arsenicals, chlorates and dinitrophenols) are more
TREATMENT toxic to animals. Most animal health problems including
reproduction, which is affected by endocrine disruption,
The successful management of herbicide poisoning
result from exposure to excessive amounts of herbicides
depends on (1) the clinicians’ understanding of the mech-
because of improper or careless use or disposal of con-
anism of herbicide toxicity and applying that understand-
tainers. The residue potential for most of these chemicals
ing to the treatment options, (2) accurate diagnosis and
is low.
assessment of the severity of intoxication, (3) mainte-
nance of vital body functions and adequate clinical moni-
toring, (4) minimization of further absorption of the REFERENCES
compound, and (5) appropriate use of specific treatment.
Treatment is usually symptomatic and supportive. Acquavella, J.F., Weber, J.A., Cullen, M.R., et al., 1999. Human ocular
Intravenous fluid should be given to promote diuresis. effects from self-reported exposure to roundup herbicides. Hum.
Toxicity of paraquat is enhanced by selenium/vitamin E Exp. Toxicol. 18, 479 486.
Ahrens, W.H., 1994. Herbicide Handbook of the Weed Society
deficiency, oxygen, and low tissue GSH peroxidase activ-
of America. seventh ed. Weed Science Society America,
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Champaign, IL.
therapy may be useful in the early stages of paraquat
Aizawa, K., Brown, H.M., 1999. Mechanism and degradation of
intoxication. Excretion of bipyridyl compounds may be
porphyrin biosynthesis inhibitor herbicide. In: Boger, P.,
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fluid therapy are contraindicated (Clark, 1971; Smith Anderson, R.J., Norris, A.E., Hess, F.D., 1994. Synthetic organic chemi-
et al., 1974). Dinis-Oliveira et al. (2006, 2007, 2008, cals that act through the porphyrin pathway. Am. Chem. Soc. Symp.
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ylate and lysine acetylsalicylate to be an effective treat- Antoniou, M., Habib, M.E.M., Howard, C.V., et al., 2012. Teratogenic
ment for paraquat-induced toxicity. These authors effects of glyphosate-based herbicides: divergence of regulatory
concluded that the antioxidant properties of these agents decisions from scientific evidence. J. Environ. Anal. Toxicol. S4,
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might be responsible for their effectiveness.
Ashby, J., Kier, L., Wilson, A.G.E., et al., 1996. Evaluation of the poten-
An effective antidote for dinitrophenol compounds is
tial carcinogenicity and gene toxicity to humans of the herbicide
not known. Affected animals should be cooled and
acetochlor. Hum. Exp. Toxicol. 15, 702 735.
sedated to help control hyperthermia. Phenothiazine tran- Baron, R.L., Johnson, C.H., 1964. Neurological disruption produced in hens
quilizers are contraindicated; however, diazepam can be by two organophosphate esters. Br. J. Pharmacol. 23, 295 304.
used to calm the animal. Atropine sulfate, aspirin, and Billington, R., Gehen, S.C., Hanley Jr, T.R., 2010. Toxicology of triazo-
antipyretics should not be used; rather, physical cooling lopyrimidine herbicides. In: Krieger, R. (Ed.), Hayes’ Handbook of