Abstract:In two separate studies with exposure duration 9 weeks or 4 weeks, male Wistar rats were dosed with di(2-ethylhexyl)phthalate (DEHP) by gavage and exposed to drinking water with or without acetone (0.5% wt/v in the 9-week study, 1.0% wt/v in the 4-week study). In the 9-week study the doses of DEHP were 0, 125, 250, 500 or 1000 mg/kg b.wt. In the 4-week study the doses of DEHP were increased to 1000, 5000 and 10,000 mg/kg b.wt. In the 9-week study, the relative liver weight was increased in the rats exposed to 500 and 1000 mg/kg b.wt. No interaction of DEHP and acetone was observed in any of the measured parameters. In the 4-week study DEHP, at the highest dose level, resulted in severe general toxicity. The group exposed to DEHP in combination with acetone was more affected. Male fertility was decreased. Body weight was decreased, and the relative weight of the liver, kidney, heart, brain and adrenals increased. The relative weight of the testes decreased in the 5000 and 10,000 mg/kg b.wt. groups. The weight of seminal vesicles and epididymals decreased at 10,000 mg/kg b.wt. In animals exposed to 5000 and 10,000 mg DEHP/kg b.wt. a severe atrophy of the seminiferous tubules and a slight diffuse Leydig's cell hyperplasia was observed. The cellular debris and conglomerates of desquamated cells found in the lumen of the seminiferous tubules were immunostained positive for vimentin. This indicates that Sertoli cell cytoplasm is included in the conglomerates -an interesting finding not previously described. No specific interaction of DEHP and acetone was observed in any of the measured parameters.It is well known that di(2-ethylhexyl)phthalate (DEHP) induces testicular atrophy in rats (Woodward 1988). Low doses of the monoester derivative mono(2-ethylhexyl)-phthalate (MEHP) have been shown to induce the same effect as the diester, and MEHP is considered the most potent metabolite of DEHP (Teirlynck et al. 1988). The role of other metabolites, e.g. 2-ethylhexanol is not fully elucidated. Both the phthalic acid and the aliphatic (ethylhexyl) part of DEHP may be toxic to the testis. The possible contribution of the aliphatic part to the testis toxicity can be examined by administering acetone concomitantly with DEHP. If enhancement of testis toxicity occurs, this may be interpreted as an indication of ethylhexyl contribution to toxicity. A small fraction of 2-ethylhexanol may be metabolised to a g-diketone, and it is well known that acetone potentiates the toxicity of g-diketones (Misumi & Nagano 1985). We have previously reported on the interaction between acetone and 2,5-hexanedione, the testis toxic metabolite of n-hexane (Larsen et al. 1991). The present study was performed to investigate a possible enhancement of the toxicity of DEHP by acetone in testis and the peripheral nervous system. Several Sertoli cell toxicants i.e. acrylamide, carbon disulfide, 2,5-hexanedione and tri-o-cresyl phosphate induce testis toxicity and peripheral neuropathy, possibly by affecting the cytoskeleton (Boekelheide 1993 the ne...