Pesticides and the induction of aneuploidy in human sperm

Abstract

Pesticides are some of the most frequently released toxic chemicals into the environment. Exposure to them has been associated with reproductive dysfunction, but the knowledge of the genotoxic risks of these substances is still limited. In vitro and in vivo, many pesticides are shown to induce aneuploidy. Analysis of sperm chromosomes by fluorescence in situ hybridization (FISH) with chromosome-specific probes has obtained increasing popularity in genetic toxicology. Sperm-FISH studies on men exposed to pesticides have yielded conflicting results: in men exposed to multiple pesticides during spraying no increased disomy frequencies in sperm were observed, although one study reported an increased rate of sex chromosome nullisomy. In contrast the two studies conducted in pesticide factories showed increased frequencies of sperm aneuploidy in exposed men compared to controls. The available data indicates that at least some of the commonly used pesticides are capable of inducing aneuploidy in human sperm when the exposure level is high enough.

Aneuploidy in Human Spermatozoa

“…Currently used pesticides are a concern because they are known aneugens that may cross the testicular barrier [reviewed in Härkönen, 2005]. Pesticides have been linked to spontaneous abortions, congenital malformations and reduced fertility.…”

Intra-individual and inter-individual variations in sperm aneuploidy frequencies in normal men

“…Evidence has also been provided to suggest that chromosome nondisjunction does not equally affect all chromosomes, with the sex chromosomes and chromosome 21 being more prone to nondisjunction than other autosomes (7). A number of factors have also been implicated in increasing chromosome aneuploidy in sperm, including male factor infertility (in particular, oligoasthenoteratozoospermia), smoking, alcohol, caffeine, drugs, pesticides, and chemotherapy (7)(8)(9)(10)(11)(12)(13)(14)(15). It is also clear from these studies that there is a great deal of variation in aneuploidy frequencies between studies.…”

Meiotic Nondisjunction: Insights into the Origin and Significance of Aneuploidy in Human Spermatozoa

“…The general consensus of these studies reveals that sperm aneuploidy levels remain remarkably consistent over time within individuals; nevertheless, there are stable variants who consistently produce higher levels of sperm aneuploidy (Rubes et al 2005 ;Tempest et al 2009 ). Preliminary data suggests that exogenous factors (e.g., diet, chemotherapy, or environment) may affect sperm aneuploidy levels resulting in a transient increase or potentially a decrease in aneuploidy levels (Harkonen 2005 ;McAuliffe et al 2012McAuliffe et al , 2014Tempest et al 2005Tempest et al , 2009Young et al 2013 ). Despite the fi ndings of signifi cantly higher levels of chromosome aneuploidy within the sperm or certain subsets of men, sperm aneuploidy is rarely examined clinically, with the test only available at a handful of reference laboratories worldwide (Carrell 2008 ;Ramasamy et al 2014 ).…”

“…To date, a handful of studies have examined the proportion of unbalanced sperm using FISH. As with translocations, the percentage of unbalanced sperm produced in inversion carriers varies widely between studies (1-54 %) (Anton et al 2002Jaarola et al 1998 ;Mikhaail-Philips et al 2004, 2005Yakut et al 2003 ), with the highest levels most likely refl ecting larger inversions. In the case of translocations and inversions, the estimates of sperm aneuploidy should be used with caution and are not generally applicable due to the fact that the vast majority of aberrations are unique.…”