ToxSci Advance Access originally published online on May 29, 2009
Toxicological Sciences 2009 110(2):411-425; doi:10.1093/toxsci/kfp109
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Published by Oxford University Press 2009.
Transgenerational Effects of Di (2-Ethylhexyl) Phthalate in the Male CRL:CD(SD) Rat: Added Value of Assessing Multiple Offspring per Litter
* Endocrinology Branch, RTD, NHEERL, ORD, USEPA, Research Triangle Park, North Carolina 27711
Sanofi-Aventis US Inc., Drug Safety Evaluation, Malvern, Pennsylvania 19355
Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27516
1 To whom correspondence should be addressed at Reproductive Toxicology Branch, TAD, NHEERL, ORD, USEPA, MD 72, Reproductive Toxicology Facility, 2525 E NC-54, Durham, NC 27713. Fax: 919 541 4017. E-mail: gray.earl{at}epa.gov.
Received April 10, 2009; accepted May 18, 2009
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Abstract |
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In the rat, some phthalates alter sexual differentiation at relatively low dosage levels by altering fetal Leydig cell development and hormone synthesis, thereby inducing abnormalities of the testis, gubernacular ligaments, epididymis, and other androgen-dependent tissues. In order to define the dose-response relationship between di(2-ethylhexyl) phthalate (DEHP) and the Phthalate Syndrome of reproductive alterations in F1 male rats, Sprague-Dawley (SD) rat dams were dosed by gavage from gestational day 8 to day 17 of lactation with 0, 11, 33, 100, or 300 mg/kg/day DEHP (71–93 males per dose from 12 to 14 litters per dose). Some of the male offspring continued to be exposed to DEHP via gavage from 18 days of age to necropsy at 63–65 days of age (PUB cohort; 16–20/dose). Remaining males were not exposed after postnatal day 17 (in utero-lactational [IUL] cohort) and were necropsied after reaching full maturity. Anogenital distance, sperm counts and reproductive organ weights were reduced in F1 males in the 300 mg/kg/day group and they displayed retained nipples. In the IUL cohort, seminal vesicle weight also was reduced at 100 mg/kg/day. In contrast, serum testosterone and estradiol levels were unaffected in either the PUB or IUL cohorts at necropsy. A significant percentage of F1 males displayed one or more Phthalate Syndrome lesions at 11 mg/kg/day DEHP and above. We were able to detect effects in the lower dose groups only because we examined all the males in each litter rather than only one male per litter. Power calculations demonstrate how using multiple males versus one male/litter enhances the detection of the effects of DEHP. The results at 11 mg/kg/day confirm those reported from a National Toxicology Program multigenerational study which reported no observed adverse effect levels-lowest observed adverse effect levels of 5 and 10 mg/kg/day DEHP, respectively, via the diet.
Key Words: di(2-ethylhexyl) phthalate; sexual differentiation; phthalate syndrome; dose response.
Disclaimer: The research described in this article has been reviewed by the National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the Agency nor does mention of trade names or commercial products constitute endorsement or recommendation for use.