Endocrine-Disrupting Pesticides - Pesticides: Evaluation of Environmental Pollution - page 619

20.8 Current Literature
A nonexhaustive selection of recent literature on endocrine disruption and pesticides is
given in the following paragraphs.
Propper (2005) has systematically reviewed literature on the mixes of endocrine com-
pounds. The literature may be distributed in three groups, that is, the hormone investigated
as being targets for disruption, the biological mechanisms of endocrine disruption, and
physiological systems that are affected by endocrine-disrupting compounds. This format
may be useful in testing the hypothesis that the disruption literature focuses on first, estro-
gens and androgens as the targets of disruption; secondly, receptor binding as the mecha-
nism of disruption and thirdly, reproduction and development as a physiological aspect.
Piersma et al. (1998) have tested six known and alleged disruptors namely ethinylestradiol
(contraceptive), coumestrol (phytoestrogen), 4-tert-octylphenol (surfactant), bisphenol (plastic
monomer), vinclozolin (fungicide), and butylbenzyl phthalate (plasticizer) by using an existing
reproductive toxicology screening test. All the compounds excluding ethinylestradiol were
clearly scored as reproductive toxicants, affecting one or more parameters such as fertility,
luteinization, spermatogenesis, and fetal development. They have concluded that endocrine
disruptors are likely to be effective in existing OECD reproductive toxicity test system used for
human risk evaluation at dosages below the maximal dosages used in former test.
Martinez-Valenzuela et al. (2009) have evaluated the genotoxic effects of pesticide
mixtures on agricultural workers using as biomarkers the sister chromatid exchangers
(SCE), mitotic index, cell proliferated kinetics, and replication index in lymphocytes of the
peripheral blood. They have also analyzed the micronuclei frequency and other nuclear
anomalies in exfoliated buccal cells of the individuals who had been exposed to pesticides
in Las Grullas, Ahome, Sinaloa, Mexico. This study afforded valuable data to estimate the
possible risk to health associated with pesticide exposure.
Quassinti et al. (2009) have studied in vitro the influence of paraquat and glyphosate
on ovarian and testicular steroidogenesis in amphibian. They tracked the production of
17β-estradiol and testosterone when ovarian tissue and testis of the water frog Rana escu-
lenta were incubated in presence of the two herbicides. These results indicate that paraquat
acts on gonadal steroidogenesis through a mechanism involving reactive oxygen species.
Glyphosate showed no effect on gonadal steroidogenesis, and it may interfere in amphib-
ian reproductive processes.
Salaberria et al. (2009) investigated the endocrine-disrupting effect of atrazine (ATZ)
herbicide. They have also studied the effects of ATZ on hepatic metabolism at the onset
of puberty in rainbow trout. The results showed that ATZ can alter hepatic metabolism,
induce estrogenic effects, and cause oxidative stress in vivo and that these effects are linked.
Orton et al. (2009) have investigated the effects of common herbicides (isoproturon,
diuron, linuron, 4-chloro-2-methylphenoxy acetic acid (MCPP), mecoprop, atrazine, sima-
zine, trifluralin, chlorpropham, bentazone, 2,4-dichlorophenoxy acetic acid (2,4-D), and
pentachlorophenol (PCP)) on endocrine end points at environmentally relevant concen-
trations. The most common effects were antiestrogenic/antiandrogenic activity in the
yeast screen, and inhibition of ovulation in vitro, accompanied by decreased testosterone
production. They concluded that novel effects of herbicides and PCP at environmentally
relevant concentrations were found, while the effects of these compounds on humans
and/or wildlife warrant further investigations.
Darras (2008) has discussed the interference of organohalogens with different processes
of brain development. He has concluded that it is essential to accurately assess the long