Sperm count/quality

As indicated in chapter 2, much of the recent increased concern regarding human reproductive health has focused on the potential adverse effects of environmental EDCs. At the centre of this concern is the hypothesis that exposure to EDCs is associated with a decrease in sperm count/quality (Carlson et al., 1992 Sharpe, 1993 Irvine et al., 1996 Weidner et al., 1999). The available data on this hypothesis are equivocal, controversial and beyond the scope of this document (Kavlock et al., 1996 Toppari et al., 1996 Cooper Kavlock, 1997 US NRC, 1999). 

The issue of time-dependent decreases or increases in sperm counts had been frequently raised prior to the report by Carlsen and coworkers on their meta-analysis of 61 selected sperm count studies.16 Their work was highly provocative, and the results of their meta-analysis study have been hotly debated by academic and nonacademic scientists, and the difficulties in obtaining consistent sperm count/quality data have also been documented. 

Table 1. Sperm Counts/Quality Studies 1993-Present...

B. NO CHANGE OR SLIGHTLY INCREASED SPERM COUNTS/QUALITY ... 

Polish lead workers Two exposure groups 25-40, 40-81 ng/dl PbB Sperm count, quality No differences in volume, count, morphology higher exposure group, lower motility Kasperczyk et al. (2008)... 

A study of sperm counts conducted worldwide suggested that an annual fall of 0.8% had occurred between 1938 and 1990. Since then, falling sperm count and quality have been reported in a number of countriesand a recent study of... 

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. 

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... 

Fecundity, fertility and sperm quality are distinct parameters that are not equivalent and are frequently confused. Sperm count and... 

In one of the first studies of data collected about sperm quality over time, Carlsen and coworkers analyzed 61 sperm-count studies from several countries published between 1938 and 1991 and showed that there was a significant decrease in mean sperm count from X 106/ml in 1940 to 66 X 106/ml in 1990 (p <... 

Since 1993, there has been a host of new studies on sperm counts and quality from men at various clinics (Table l).17 Results... 

The work by Fisch and coworkers on sperm quality of men from vasectomy clinics in New York, California, and Minnesota revealed no change in sperm counts, sperm volume, or sperm motility in the period 1970 through 1994.18 They did, however, show surprisingly large differences in sperm counts between the three locations. Sperm counts in New York, California, and Minnesota were 131.5,72.7, and 100.8 x 106/ml, respectively, and still... 

Infertility affects about 15% of couples and can be defined as an inability to conceive following one year of unprotected intercourse with the same partner. Fertility can be reduced by many factors in the male or female partner, or both. In the male, infertility often involves diminished production of sperm or diminished quality of sperm. Since Demi appeared to have a normal menstrual cycle, a sperm count was arranged for Milton. The results showed the count to be within normal limits, but at the lowest end of the range, so an appointment was organized for the couple at a fertility clinic. However, while waiting for the appointment, Demi became pregnant at last. 

What of the effects in humans While there is evidence, some of it controversial, that changes have occurred in the reproductive systems of humans in various countries throughout the world over the last fifty years or so, ascribing these changes to particular chemicals, or even to chemicals at all, has been difficult. There has been an increase in testicular cancer as well as breast cancer since 1945, particularly in certain countries. Data from studies of populations in some countries, for example Finland, have indicated that sperm counts and the quality of the sperm in males have declined over the same time period, but by no means aU studies have found this and some have found the reverse. In some places there has been an apparent increase in disorders of the male reproductive system such as... 

Ovarian tumors were found significantly in the female offspring of treated mice. A decrease in reproductivity was observed in the female offspring of treated mice, where alteration of reproductive tracts was observed in the male offspring. Results from rodent studies also indicate that potent estrogenic chemicals such as diethylstilbestrol can adversely affect sperm counts and quality. 

Sperm counts in men have declined by about 50% during the time period 1940-90, from an average of 113 million per milliliter of semen in 1940 to an average of 66 million in 1990. During the same time frame there has been a decrease in seminal volume from 3.40 to 2.75 ml. 51 The reasons for the observed decline in semen quality are exposures to pesticide mixtures 52 and other xenobiotic endocrine disruptors, 53 maternal consumption of beef-containing anabolic steroids 54 and other xenobiotics, and tobacco smoking. 55 ... 

EPA s review of recent epidemiologic studies of enviroiunental lead e q)0-sure and reproductive function concludes that there is strong evidence that increasing lead exposure is associated with reduced male fecundity or fertility, decreases in sperm count, and reduced sperm velocity and motility. EPA s draft report further concludes that deleterious associations with sperm count and quality are observed in occupationally exposed men who have mean BLLs as low as 20-45 pg/dL. EPA concluded that there was some association between maternal lead exposure and low birth weight toxicologic studies in animals have shown that lead exposme during early fetal development can result in abnormal retinal development and alterations in the developing hematopoietic and hepatic systems. 

Aschengrau, A., Zierler, S., Cohen, A., 1993. Quality of community drinking water and the occurrence of late adverse pregnancy outcomes. Arch. EnviroiL Health 48, 105—113. Assennato, G., Paci, C., Baser, M.E., MoUnini, R., Candela, R.G., Altamura, BAl., et al., 1986. Sperm count suppression without endocrine dysfunction in lead-exposed men. Arch. Environ. Health 41, 387—390. 

Sperm evaluation11 Sperm number (count, concentration), quality (morphology, motility), chromosomal defects... 

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