Synergistic disruption of external male sex organ development by a mixture of four antiandrogens.
BACKGROUND
By disrupting the action of androgens during gestation, certain chemicals present in food, consumer products, and the environment can induce irreversible demasculinization and malformations of sex organs among male offspring. However, the consequences of simultaneous exposure to such chemicals are not well described, especially when they exert their actions by differing molecular mechanisms.


OBJECTIVE
To fill this gap, we investigated the effects of mixtures of a widely used plasticizer, di(2-ethylhexyl) phthalate (DEHP); two fungicides present in food, vinclozolin and prochloraz; and a pharmaceutical, finasteride, on landmarks of male sexual development in the rat, including changes in anogenital distance (AGD), retained nipples, sex organ weights, and malformations of genitalia. These chemicals were chosen because they disrupt androgen action with differing mechanisms of action.


RESULTS
Strikingly, the effect of combined exposure to the selected chemicals on malformations of external sex organs was synergistic, and the observed responses were greater than would be predicted from the toxicities of the individual chemicals. In relation to other hallmarks of disrupted male sexual development, including changes in AGD, retained nipples, and sex organ weights, the combined effects were dose additive. When the four chemicals were combined at doses equal to no observed adverse effect levels estimated for nipple retention, significant reductions in AGD were observed in male offspring.


CONCLUSIONS
Because unhindered androgen action is essential for human male development in fetal life, these findings are highly relevant to human risk assessment. Evaluations that ignore the possibility of combination effects may lead to considerable underestimations of risks associated with exposures to chemicals that disrupt male sexual differentiation.
Christiansen
Sofie
S
Department of Toxicology and Risk Assessment, National Food Institute, Technical University of Denmark, Søborg, Denmark.
Scholze
Martin
M
Dalgaard
Majken
M
Vinggaard
Anne Marie
AM
Axelstad
Marta
M
Kortenkamp
Andreas
A
Hass
Ulla
U
D000726:Androgen Antagonists / Q000633:toxicity*; D000818:Animals; D004051:Diethylhexyl Phthalate / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D018120:Finasteride / Q000633:toxicity; D005837:Genitalia, Male / Q000002:abnormalities / Q000187:drug effects*; D007093:Imidazoles / Q000633:toxicity; D008297:Male; D019055:No-Observed-Adverse-Effect Level; D009929:Organ Size / Q000187:drug effects; D010080:Oxazoles / Q000633:toxicity; D051381:Rats; D017208:Rats, Wistar; D012733:Sex Differentiation / Q000187:drug effects*
D000726:Androgen Antagonists; D007093:Imidazoles; D010080:Oxazoles; D018120:Finasteride; C045362:prochloraz; D004051:Diethylhexyl Phthalate; C025643:vinclozolin