Semen quality

While considerable attention is given to the question of male fertility, the incidence of infertility or sub-fertility in the population is difficult to measure and it is not known to what extent measures of semen quality, for example, are indicators of male fertility as such. 

The issue of whether sperm counts are declining has been the focus of most media attention. A debate still continues as to whether the reported changes in sperm quality are genuine. In 1992, an article described the meta analysis of available data on semen quality in normal men, taken from reports published between the period 1938-1990. This analysis showed a 50% decline in sperm concentration... 

Controversy will continue to persist over allegations that sperm counts are declining. Prospective studies on semen quality in fertile men involving centres in... 

Europe, the USA and Japan are under way. In these studies, semen analysis methodology and subject selection criteria have been standardised to address whether there are region-specific differences in semen quality. These data can then be used as a reference point for any studies on future decline in sperm counts. More importantly, it still remains to be demonstrated whether the reported decrease in semen quality is sufficient to compromise fertility. 

It is widely accepted that men with testicular cancer have a higher incidence of abnormalities associated with impaired spermatogenesis, both in the cancerous testis but also in the contralateral testis. Men diagnosed as having testicular cancer often have very poor semen quality, with sperm concentrations of less than 10 million/ml compared to healthy men with > 50 million/ml." It is thought that gonadal function is abnormal even before testicular cancer develops, ... 

Juhler RK, Larsen SB, Meyer O, et al. 1999a. Human semen quality in relation to dietary pesticide exposure and organic diet. Arch Environ Contam Toxicol 37 415-423. 

Swan, S.H., Brazil, C., and Drobnis, E.Z. et al. (2003a). Geographic differences in semen quality of fertile US males. Environmental Health Perspectives 111, 414 20. 

In addition, it has been suggested that short-term exposure to phytoestrogens during adulthood does not affect male sex hormone concentrations or semen quality (Mitchell et al, 2001). 

There has been some speculation that estrogenic compounds may adversely affect the fertility of men by reducing testosterone levels and sperm counts (Atanassova et al, 2000). To date, however, the limited information available suggests that consumption of phytoestrogens does not affect reproductive hormones or semen quality (Nagata, 2000 Nagata et al., 2001 Mitchell et... 

In some animals, consumption of a phytoestrogen-rich diet can cause temporary infertility and reproductive system disorders (Irvine, 1999). In humans, lower testosterone levels and a decline in human semen quality over the past century have been luiked to increased exposure to environmental endocrine disrupters (EDCs) (Sharpe and Skakkebaek, 1993). Furthermore, cases of sexual impotence have been reported in males exposed to synthetic estrogens in the pharmaceutical industry (Mattison et al., 1990). If this might be the case, the fetal-prepubertal period and Sertoli cell development would be of critical importance (Sharpe and Skakkebaek, 1993). However, an adverse effect of phytoestrogens on male fertility has yet to be proven. Recent work (Mitchell et al., 2001) addressing this point led to the conclusion that up to 40 mg/day of isoflavones over a two-month period had no effects on gonadotrophin and... 

Not specified Imperial College of Science, Technology and Medicine Lead and male reproductive function, evaluate impact of changes in indicators of semen quality and reproductive hormones as function of occupational lead exposure ILZRO... 

Alexander BH, Checkoway H, van Netten C, et al. 1996. Semen quality of men employed at a lead smelter. Occup Environ Med 53 411-416. 

Fisher-Fischbein J, Fischbein A, Meimick HD, et al. 1987. Correlation between biochemical indicators of lead exposure and semen quality in a lead-poisoned firearms instructor. JAMA 257 803-805. 

Traditional and organic farmers Traditional versus organic farmers. No measure of diet No significant difference in conventional measures of semen quality found between organic and traditional farmers (Larsen et al., 1999)... 

Jensen TK, Giwercman A, Carlsen E, Scheike T and Skakkebaek NE (1996) Semen quality among members of organic food associations in Zealand, Denmark . Lancet, 347, 1844-1844. 

Larsen SB, Spano M, Giwercman A and Bonde JP (1999) Semen quality and sex hormones among organic and traditional Danish farmers . Occupational and Environmental... 

Hours since last ejaculation (Jouannet et al. 1981) and testis size (Kim and Lee 1982 Harvey and May 1989) both show the expected positive relationships (Table 1). Chronic alcoholism has a major negative influence on semen quality (Gomathi et al. 1993), but small amounts of alcohol are associated with more sperm in masturbatory ejaculates (Gerhard et al. 1992), as in Table 1. Autopsy studies have shown that the number of sperm manufactured per day by human testes declines by about 5 million for every year of a man s life after the age of about 25 y (Neaves et al. 1984). The decline per insemination of about 13 million for each year of age found in the Manchester study matches this autopsy work well, being the decline expected if the interval between ejaculations were 2—3 days. 

Auger, J., Kunstmann, J. M., Czyglik, F. and Jouannet, P. (1995). Decline in semen quality among fertile men in Paris during the past 20 years. New England Journal of Medicine 332, 327—8. 

Irvine, S., Cawood, E., Richardson, D., MacDonald, E. and Aitken, J. (1996). Evidence of deteriorating semen quality in the United Kingdom birth cohort study in 577 men in Scotland over 11 years. British Medical Journal 312,467—471. 

Ratcliffe JM, Schrader SM, Steenland K, et al. 1987. Semen quality in papaya workers with long term exposure to ethylene dibromide. Br J Ind Med 44 317-326. 

Camarasa and Serra-Baldrich [94] reported allergic contact dermatitis after repeated contact with TPP-treated plastics. Meeker and Stapleton [95] indicated endocrine disruptive properties for TPP and TDCiPP, through a negative correlation with semen quality and thyroid hormone levels, respectively. Kanazawa et al. [71] associated mucosal symptoms of the sick building syndrome with high indoor exposure to TBP. These symptoms include irritation to the eyes, nose, and throat symptoms such as flushing, and mucosal symptoms such as irritation to the eyes, nose, and throat the latter symptoms were strongly associated with TBP levels in air and dust. 

Meeker JD, Stapleton HM (2010) House dust concentrations of organophosphate flame retardants in relation to hormone levels and semen quality parameters. Environ Health Persp 118 318-323... 

Phthalates are suspected of acting as endocrine disrupters also in humans, affecting male and female reproductive tract development. Exposure to PAEs in adult men has been associated with semen quality and alterations in sexual behavior [104], and with endometriosis and intrauterine inflammation (which is a risk factor for prematurity) in adult women [105, 106], as well as other effects. These studies suggest that DEHP may play a role in inducing the intrauterine inflammatory process. Besides the reproductive effects of PAEs, recent studies have also shown the genotoxicity of DEHP, DBP, and DiBP in human lymphocytes and mucosal cells [107,108]. 

Hauser R, Meeker JD, Duty S, Silva MJ, Calafat AM (2006) Altered semen quality in relation to urinary concentrations of phthalate monoester and oxidative metabolites. Epidemiology 17 682-691... 

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