Effects of exposure of pre-pubertal boars to di(2-ethylhexyl) phthalate on their frozen-thawed sperm viability post-puberty

Late effects of pre-pubertal oral exposure to di(2-ethylhexyl) phthalate (DEHP), a plastic softener used in, for example, polyvinyl chloride-products, on semen quality in young boars have not been clear-cut. The aim of this study was to determine whether stress imposed on spermatozoa would reveal such effects. Semen was collected from post-pubertal boars (8-9 months of age), which had been exposed to 300 mg kg(-1) body weight of DEHP per os three times a week from 3 to 7 weeks of age and from control siblings given placebo (water). The semen was cryopreserved and examined for plasma membrane integrity post-thaw using the short hypo-osmotic swelling test and flow cytometry (propidium iodide /SYBR-14). Sperm motility was assessed by computer-assisted sperm analysis. No significant difference in plasma membrane integrity could be found between the groups. The DEHP-exposed group had a significantly lower percentage of linearly motile spermatozoa at 30 min (P < 0.05) and 120 min (P < 0.001) after thawing, and a larger amplitude of lateral displacement of the head 120 min after thawing (P < 0.05), compared with controls. In summary, spermatozoa from boars pre-pubertally exposed to low doses of DEHP, showed kinematic deviations post-thaw that could be related to DEHP exposure.