Do environmental and occupational factors influence semen quality?

A recent Scientific Reports study investigates environmental and occupational factors that affect semen quality.

Study: Association of living environmental and occupational factors with semen quality in Chinese men: A cross-sectional study. Image Credit: Gorodenkoff / Shutterstock.com

Background

A decrease in birth rates and an increase in infertility have been recorded globally. In China, for example, the infertility rate has been estimated to be 12.5% and rising.

Infertility is defined as failure to conceive after 12 months of regular and unprotected sexual intercourse. In approximately 40% of infertile couples, men were found to be responsible for the condition.

Male fertility is associated with environmental, genetic, and occupational factors. Since most men seldom change their living environment and continue the same job for prolonged years, they are often exposed to the same factors that may contribute to their infertility. Thus, in addition to genetic predisposition, assessing the occupational and environmental factors linked to male fertility is imperative.

Previous studies have indicated that people engaged in the transportation business have low semen motility. These studies have also highlighted that people close to toxic chemicals, particularly those who work in the printing and oil industries, exhibit poor fertility.

However, some studies have not reported any association between semen quality and occupation. These contradictory views indicate the need for more research to confirm whether certain occupations affect semen quality in men.

Living environments have been linked to male fertility. For example, the extent of cellular telephones has been negatively correlated with sperm motility and concentration. House renovating was linked to the use of ammonia, benzene, and formaldehyde, which may also affect semen quality.

A single fertility center cohort study also indicated that environmental noise is linked with sperm abnormality.

About the study

The current study assesses how environmental and occupational factors influence male fertility. Three questionnaires based on demographic characteristics, living environmental factors, and occupational effects were developed considering the living habits of typical Chinese people.

Couples who attended free pre-pregnancy medical examinations at Guangzhou Women and Children’s Medical Center in China were recruited for the study. Male partners with a medical history of infertility-related diseases such as cryptorchidism, azoospermia, or varicocele were excluded. Male participants who were obese or overweight were also not considered in this study.

A total of 465 male partners between 31 and 43 years of age were considered for the study. In addition to completing the three lifestyle questionnaires, physical examinations and semen analysis were conducted on the same day.

All participants were requested to abstain from sexual activity for at least three to seven days from the date of analysis. Semen quality assessment comprised evaluation of semen pH, volume, count, concentration, progressive motility, and total motility.

Study findings

The mean age of the participants was 37.5 years, and the mean body mass index (BMI) was 23.85 kg/m². About 21% of the participants were alcohol consumers, and 9% were smokers. All study participants had permanent jobs.

Individuals who lived close to power lines and substations had higher sperm counts and greater sperm progressive motility. These findings indicate that electric field energy may positively influence semen quality; however, its actual effects must be further studied.

Comparatively, individuals living close to chemical factories exhibited poor semen concentration. These observations corroborate previous reports that industrial chemicals have a harmful effect on semen quality.

Typically, multiple factors damage human fertility gradually in a cumulative way. In most cases, people do not take individual factors seriously unless problems of infertility occur. It is important that the pregnancy consultation clinics understand these environmental and occupational factors before offering proper treatment.

Conclusions

The current study has some limitations, including the assessment of only the Southern Chinese population. Since other ethnic groups were not included, the generalizability of these findings is limited.

An additional limitation is that the current study only examined epidemiological risk factors and did not consider specific substances that may contribute to male infertility. There is a high possibility of interference of confounding factors such as sleep duration within a day, economic condition, and dietary structure, all of which were not considered in this analysis.

Despite these limitations, the study findings highlight that certain environmental and occupational factors such as computer use, working in a power line, transformer room, substation, and chemical plants, and certain house renovating products influence semen quality. In the future, similar studies with larger sample sizes are needed to validate these findings.