Assessment of DNA integrity (COMET assay) in sperm cells of boron-exposed workers

Abstract

An extension of a male reproductive study conducted in a boric acid/borate production zone at Bandırma, Turkey, is presented. The relation between DNA-strand breaks (COMET assay, neutral and alkaline version) in sperm cells and previously described sperm quality parameters was investigated in boron-exposed males. A correlation between blood boron levels and mean DNA-strand breaks in sperm was weak, and DNA-strand breaks in sperm were statistically not different between control and exposed groups. Therefore, increasing boron exposures had no additional contribution in addition to already pre-existing DNA-strand breaks in the sperm cells. Weak but statistically significant correlations between DNA-strand breaks and motility/morphology parameters of sperm samples were observed in the neutral version of the COMET assay, while correlations between the same variables were statistically not significant in the alkaline version. A likely reason for these negative results, even in highly exposed humans, is that experimental exposures that had led to reproductive toxicity in animals were significantly higher than any boron exposures, which may be reached under realistic human conditions.

Is There an Association Between Extreme Levels of Boron Exposure and Decrease in Y:X Sperm Ratio in Men? Results of an Epidemiological Study

“…The mean blood boron concentration of the high exposure group in our study was 223.89±69.49 (152.82-454.02) ng/g and no boron-mediated unfavorable effects on reproductive toxicity parameters of male workers were observed. 3,4 The results of our study were in agreement with those of the study conducted in China. Accordingly, both studies clearly indicate that boronmediated adverse effects on male reproduction do not seem possible even under extreme occupational exposure conditions.…”

“…The present study was performed using the blood and semen samples obtained within the scope of our "Boron Project -I", which was completed in 2010. 3,4 The "Boron Project -I" was conducted in Bandırma boric acid production zone and 204 workers were enrolled in that study. After the project was completed, the remaining semen samples were stored under appropriate conditions (cryopreserved in liquid nitrogen).…”

Recent Epidemiological Studies on Boron Exposure – Contradiction between Hazard and Risk-Based Assessments

“…The study conducted in Turkey provided daily exposure levels under worst case exposure conditions [1]. Even under this exposure conditions boron mediated reprotoxic effects have not been reported [10][11][12][13]. Additionally, boron mediated reprotoxic effects in male workers were not reported even in the Chinese study.…”

“…However, boron mediated unfavorable effects were not reported. Additionally, the correlations between blood/urine boron concentrations and the above mentioned parameters were statistically not significant [10][11][12][13][14].…”

Motility Evaluation and Cryopreservation of Fish Sperm Exposed by Water-Borne and Food-Borne Boron

“…Similarly, a decrease in motility percentages was also reported in frog and some mammalian species (Fort et al, 1999;Scialli et al, 2010). In humans, no adverse effects of B on male reproduction can be demonstrated (Liu et al, 2005;Duydu et al, 2012). However, it was emphasized that the possibility of a bias in the selection of subjects for semen evaluation may have been emerged (Scialli et al, 2010).…”