Objective To understand the relationship between urinary benzophenone (BP) ultraviolet absorber exposure and semen quality in men of reproductive age attending a fertility center.

Methods A total of 445 men of reproductive age who underwent semen examination at the Reproductive Medicine Center of Shenzhen People's Hospital, Guangdong Province, China from 2018 to 2019 were selected for questionnaire survey and the detection of five urinary BP ultraviolet absorbers2, 4-dihydroxybenzophenone(BP-1), 2, 2', 4, 4'-tetrahydroxybenzophenone(BP-2), benzophenone-3(BP-3), 2, 2'-dihydroxy-4-methoxybenzophenone(BP-8), 4-hydroxybenzophenone(4-OH-BP). A computer-assisted semen analysis system was used to analyze semen quality. According to the World Health Organization Laboratory Manual for the Examination and Processing of Human Semen (Fifth Edition), men were assigned to groups with normal and abnormal semen quality. Multiple linear regression and logistic regression models were used to analyze the relationship between urinary BP ultraviolet absorber exposure and semen quality.

Results No statistical differences were found in age, body mass index, duration of abstinence, smoking, and alcohol consumption between the normal and abnormal semen quality groups (P >0.05). The age of the abnormal sperm concentration group was significantly higher than that of the normal group, while the age of the abnormal sperm count group was significantly lower than that of the normal group. Body mass index of normal group was higher than that of the total sperm motility abnormality group. The duration of abstinence was significantly different between the two groups (P=0.028). After correcting for age, body mass index, days of abstinence, smoking, and alcohol consumption, multiple linear regression results showed that compared to the lowest tertile of BP-1, the highest tertile of BP-1 was positively associated with sperm immobility (β=0.16, 95%CI: 0.004-0.30) and negatively associated with high percentage of activated spermatozoa (β=-0.24, 95%CI: -0.54--0.01). Logistic regression model showed that the highest tertile of BP-1 was associated with a 1.74-fold risk of abnormal sperm forward motility compared to the lowest tertile (OR=1.74, 95%CI: 1.03-2.93), and the test for trend was statistically significant (P=0.029). The corrected OR (95%CI) for abnormal sperm forward motility was 1.91 (1.13, 3.24) for men with the second tertile of 4-OH-BP compared to those with the lowest tertile.

Conclusion Urinary BP-1 and 4-OH-BP levels in the men of reproductive age attending the reproductive centre may be associated with decreased semen quality. BP-1 and 4-OH-BP mainly affect the kinetic indicators of spermatozoa. The underlying mechanisms need to be further explored.