Study raises questions about chemicals in packaging and pet food
Adverse temporal trends in human semen quality and cryptorchidism in infants have been associated with exposure to environmental chemicals (ECs) during development.
A Warning for Dogs, and Their Best Friends, in Study of Fertility, nytimes, AUG. 9, 2016.
Here we report that a population of breeding dogs exhibit a 26 year (1988–2014) decline in sperm quality and a concurrent increased incidence of cryptorchidism in male offspring (1995–2014). A decline in the number of males born relative to the number of females was also observed.
Environmental chemicals impact dog semen quality in vitro and may be associated with a temporal decline in sperm motility and increased cryptorchidism, nature, 09 August 2016.
ECs, including diethylhexyl phthalate (DEHP) and polychlorinated bisphenol 153 (PCB153), were detected in adult dog testes and commercial dog foods at concentrations reported to perturb reproductive function in other species. Testicular concentrations of DEHP and PCB153 perturbed sperm viability, motility and DNA integrity in vitro but did not affect LH stimulated testosterone secretion from adult testis explants.
Decline in dog fertility could be a wake-up call for humans, MNN, August 10, 2016.
The direct effects of chemicals on sperm may therefore contribute to the decline in canine semen quality that parallels that reported in the human.
DES exposure has been associated with increased risk of cryptorchidism
2011 Study Abstract
Prospective clinical studies have suggested that the rate of congenital cryptorchidism has increased since the 1950s. It has been hypothesized that this may be related to environmental factors. Testicular descent occurs in two phases controlled by Leydig cell-derived hormones insulin-like peptide 3 (INSL3) and testosterone. Disorders in fetal androgen production/action or suppression of Insl3 are mechanisms causing cryptorchidism in rodents. In humans, prenatal exposure to potent estrogen Diethylstilbestrol (DES) has been associated with increased risk of cryptorchidism. In addition, epidemiological studies have suggested that exposure to pesticides may also be associated with cryptorchidism. Some case–control studies analyzing environmental chemical levels in maternal breast milk samples have reported associations between cryptorchidism and chemical levels. Furthermore, it has been suggested that exposure levels of some chemicals may be associated with infant reproductive hormone levels.
Exposure to estrogens/estrogenic agents
2011 Study Conclusion
Various xenobiotics have been found to disrupt the endocrine system in animals. Reduction in the dominance of androgens to estrogens, and interference with androgen or Insl3 production or action during fetal life, are apparent mechanisms causing cryptorchidism in animals. When evaluating associations between fetal exposure to estrogenic agents and cryptorchidism in humans, exposure to DES was associated with an increased risk of cryptorchidism. Studies evaluating pesticide use in a geographical area or parental possible occupational exposure to pesticides, have suggested that also exposure to them may be associated with an increased risk of cryptorchidism in boys. Some case–control studies evaluating maternal breast milk levels of chemicals have reported associations between congenital cryptorchidism and the levels of environmental chemicals with possible endocrine disrupting activities. No clear positive association was reported in studies evaluating levels of endocrine disrupting chemicals in placenta, cord serum or maternal serum. Maternal breast milk phthalate and PBDE levels have shown anti-androgen-like associations with infant reproductive hormone levels. More studies are needed to confirm the observed associations and to evaluate associations between cryptorchidism and combined exposures.
Sources and more information
Cryptorchidism and endocrine disrupting chemicals, sciencedirectpii/S0303720711006782, doi:10.1016/j.mce, 2011.11.
In utero exposure to Diethylstilbestrol is associated with terrible side-effects in DES Sons
The in utero effects of diethylstilbestrol on the human male genital tract are reported in our followup study of male offspring of mothers treated with diethylstilbestrol. Anatomical and functional abnormalities were significantly greater in male patients exposed to diethylstilbestrol compared to male controls whose mothers were all participants in a prospective, randomized double-blind study on the effects of diethylstilbestrol on pregnancy at our hospital during the early 1950s. Epididymal cysts, hypotrophic testes and capsular induration of the testes were among the more common genital lesions found in more than 25 per cent of 159 male patients exposed to diethylstilbestrol compared to a 6.8 per cent incidence in 161 male controls. Spermatozoal analysis revealed severe pathological changes (Eliasson score more than 10) in 32 per cent of 31 patients exposed to diethylstilbestrol and 0 per cent of 20 male controls. Abnormal findings on physical examination combined with severe sperm abnormalities (Eliasson score more than 10) were found in 23 per cent of the male patients exposed to diethylstilbestrol versus none of the male controls. Cytologic examinations revealed no malignant cells from urine samples before and after prostatic massage or ejaculation, prostatic fluids and aspirates from epididymal cysts.
Sources: NCBI, J Urol. 1977 Apr;117(4):477-80., PMID: 850321, Pathological semen and anatomical abnormalities of the genital tract in human male subjects exposed to diethylstilbestrol in utero.
Analyses of the spermatozoa have revealed severe pathological changes (Eliasson score greater than 10) in 134 diethylstilbestrol-exposed men (18 per cent) and 87 placebo-exposed men (8 per cent).
Further investigation of the 26 diethylstilbestrol-exposed men with testicular hypoplasia has revealed that 65 per cent had a history of cryptorchidism. Only 1 of the 6 placebo-exposed controls with testicular hypoplasia had a history of testicular maldescent.
Although none of our Diekmann’s lying-in study group has had carcinoma to date one must keep in mind the reported increased risk of testicular carcinoma in testes that are or were cryptorchid. A 25-year-old man who was not part of the study group was treated recently by us for a testicular carcinoma ( mixed anaplastic seminoma plus embryonal cell carcinoma) and he had a history of diethylstilbestrol exposure in utero and cryptorchidism.
Sources: NCBI, J Urol. 1979 Jul;122(1):36-9., PMID: 37351, Association of diethylstilbestrol exposure in utero with cryptorchidism, testicular hypoplasia and semen abnormalities.