Background: Trihalomethanes (THMs) and haloacetic acids (HAAs) are regulated disinfection by-products (DBPs); their joint reproductive toxicity in drinking water is unknown.

Objective: We aimed to evaluate a drinking water mixture of the four regulated THMs and five regulated HAAs in a multigenerational reproductive toxicity bioassay.

Methods: Sprague-Dawley rats were exposed (parental, F₁, and F₂ generations) from gestation day 0 of the parental generation to postnatal day (PND) 6 of the F₂ generation to a realistically proportioned mixture of THMs and HAAs at 0, 500×, 1,000×, or 2,000× of the U.S. Environmental Protection Agency’s maximum contaminant levels (MCLs).

Results: Maternal water consumption was reduced at ≥ 1,000×; body weights were reduced at 2,000×. Prenatal and postnatal survival were unaffected. F₁ pup weights were unaffected at birth but reduced at 2,000× on PND6 and at ≥ 1,000× on PND21. Postweaning F₁ body weights were reduced at 2,000×, and water consumption was reduced at ≥ 500×. Males at 2,000× had a small but significantly increased incidence of retained nipples and compromised sperm motility. Onset of puberty was delayed at 1,000× and 2,000×. F₁ estrous cycles and fertility were unaffected, and F₂ litters showed no effects on pup weight or survival. Histologically, P₀ (parental) dams had nephropathy and adrenal cortical pathology at 2,000×.

Conclusions: A mixture of regulated DBPs at up to 2,000× the MCLs had no adverse effects on fertility, pregnancy maintenance, prenatal survival, postnatal survival, or birth weights. Delayed puberty at ≥ 1,000× may have been secondary to reduced water consumption. Male nipple retention and compromised sperm motility at 2,000× may have been secondary to reduced body weights.

Citation: Narotsky MG, Klinefelter GR, Goldman JM, DeAngelo AB, Best DS, McDonald A, Strader LF, Murr AS, Suarez JD, George MH, Hunter ES III, Simmons JE. 2015. Reproductive toxicity of a mixture of regulated drinking-water disinfection by-products in a multigenerational rat bioassay. Environ Health Perspect 123:564–570;  http://dx.doi.org/10.1289/ehp.1408579

Address correspondence to M.G. Narotsky, U.S. Environmental Protection Agency, NHEERL, Research Triangle Park, NC 27711 USA. Telephone: (919) 541-0591. E-mail: narotsky.michael@epa.gov

We thank M. Hoopes, I. Thillainadarajah, and A. Wiggins for their tremendous technical contributions. We are also grateful to N. Roberts for work with sperm extracts; G. Marrs, J. Seeley, C. Houle, and N. Allison for pathological examinations; P. Killough and E. Puckett for designing and constructing specialized water bottle holders; and S. Parvez for discussion of onset-of-puberty data. We also appreciate the support of L. Teuschler, M. Miltner, S. Richardson, J. Pressman, T. Speth, and G. Rice.

The information in this document has been funded wholly by the U.S. Environmental Protection Agency. It has been subjected to review by the National Health and Environmental Effects Research Laboratory and approved for publication. Approval does not signify that the contents reflect the views of the agency, nor does mention of trade name or commercial products constitute endorsement or recommendation for use.

The authors declare they have no actual or potential competing financial interests.

Received: 21 April 2014 Accepted: 12 February 2015 Advance Publication: 19 February 2015 Final Publication: 1 June 2015