Commentary on “Will male semen quality improve with environmental quality?”

The adverse effect of environmental pollution, climate change, and bad lifestyles on human reproductive fitness and health is reported in a large body of literature and is a matter of attention from the scientific community and governments all over the world. Although several reproductive processes from gametogenesis up to embryo and fetal development are affected by a variety of environmental stressors, most of the data available in the literature are related to sperm physiology and quality.¹ I read with interests the article by Dai et al.² that reports an improvement of sperm quality along with environmental quality in Wenzhou, a highly populated area in the south of Zhejiang province, coastal eastern China.

Here, a program for environmental protection and remediation has been developed since 2014 resulting in a generalized improvement of most of the environmental parameters such as air and water quality. It is also of interests that this program, based on the reduction of emissions of contaminants in water and air, has also benefited from the use of clean solar and wind energies.

At the beginning of this program, the authors started to monitor the seminal fluids of infertile males and concluded the study in 2019. Patients were selected on the basis of specific criteria, demographic and occupational characteristics, and their seminal fluids were evaluated according to WHO 2010 guidelines.

This study reports a 5-year survey and has examined almost 23 000 seminal fluids, therefore it is ambitious and well designed. In particular, the selection of patients enrolled in the survey has been well organized on the basis of homogeneous characteristics. In addition, since these analyses were carried out in the same center and, presumably, by the same operators, it allowed excluding variability sources of the multicenter studies related to the subjective evaluation due to the operator, the instrumentation, and the peculiar investigation method of each laboratory.

So far, many studies have demonstrated that environmental pollutants induce significant adverse effects on sperm quality and consequently reproductive disorders and detrimental effects on male fertility. It is well known the importance of the paternal effect on embryo development³ which means that poor spermatozoa lead to poor blastocyst formation and sometimes even to late postimplantation development. The latter is particularly related to sperm genomic integrity, e.g., DNA fragmentation, which has not been investigated in this study, although the authors mentioned that they would include this test in a further study.

In 2016, a pilot biomonitoring study⁴ quoted in this paper has shown the impairment of some physiological parameters in seminal fluids of men living in highly polluted areas in the south of Italy. In particular, the main impact was observed on reduced sperm motility which is consistent with data of the study by Dai et al.² Confirming the role of sperm motility in affecting male fertility may be of encouragement for deep investigations into the biological mechanisms that underlie their relationship since the extent to which they interact with each other is still poorly explored.

What also emerges in this paper is the role of abnormal sperm morphology which seems to be significantly related to occupational exposure to toxicants and does not ameliorate along with environmental improvement with the exception of a decreasing trend. However, sperm morphology is still a matter of debate since no clinical relevance and/or predictive value have been yet fully ascertained.

The strength of this paper resides in providing a topical study since (1) statistics report that the male factor is responsible for about 50% of the couple infertility, thus creating a crescent alarm on the impact of sperm impairment on the reproductive outcome; (2) the comforting data on the concomitant improvement of environmental contamination and sperm parameters support emerging evidence on the sperm resilience to environmental disturbances.

In contrast, in this and other similar studies, some confounding factors should be taken into consideration such as intralaboratory variability, standardization and reproducibility of methods, and the role of female factor in the couple infertility.

At last, this paper could have been enriched with a greater scientific background on the role of spermatozoon in the fertilization process and a dissertation of current literature on the involvement of genomic integrity, epigenetic factors, and oxidative stress on sperm physiology and functionality. This information would have made the work more comprehensible to the nonexpert readership.

COMPETING INTERESTS

The author declares no competing interests.