In Vitro Effects of Tire Debris Organic Extracts on Human Spermatozoa

ABSTRACT

Background & objectives: Environmental pollutants have detrimental effects on the reproductive function of human being and of animals. This study was aimed at evaluating the effects of tire debris, a fraction of particulate matter derived from tire wear, on motility and morphology of human spermatozoa. Methods: spermatozoa from ten healthy men were incubated for 4 hours with 10, 50 and 75 μg/ml of tire debris organic extract (TDOE). Sperm motility and morphology were evaluated according to WHO guidelines; the presence of apoptosis and necrosis was assessed by the AnnexinV/Propidium iodide assay. Ultrastructure of sperm organelles was observed by transmission electron microscopy. Results: incubation with 10 μg/ml of TDOE did not affect sperm quality, except for the value of apoptosis (median: 8% vs. 6%; P<0.01). Sperm motility and sperm morphology percentages (P<0.01)decreased when sperm were treated with 50 and 75 μg/ml TDOE and the percentage of apoptotic and necrotic sperm (P<0.01) increased concomitantly. At the same concentrations TEM analysis showed an increased percentage of reacted and swollen acrosomes, disrupted chromatin and altered axonemes. Interpretation & conclusions: the organic part of tire debris is potentially harmful to spermatozoa, particularly at a concentration of 50-75 μg/ml, inhibiting motility and compromising morphological integrity. Nevertheless, these results cannot yet be extrapolated to the in vivo outcome due to the lack of studies focused on this issue.