Jennifer Freeman, Ph.D., María S. Sepúlveda, D.V.M., Ph.D.
NIEHS grantees report that zebrafish embryos exposed to the agricultural herbicide atrazine, a suspected endocrine-disrupting chemical, later developed reproductive problems and had offspring with physical deformities. The study provides evidence supporting atrazine as an endocrine-disrupting chemical that can cause reproductive problems in adults and affect the next generation.
Atrazine is predominately used in the Midwestern United States to control weeds on field crops and often contaminates drinking water supplies. Most previous studies of the herbicide have examined either developmental, pubertal, or adult exposures; however, this new study looked at how development exposure affects adults and their offspring. The researchers exposed zebrafish to 0, 0.3, 3, or 30 parts per billion (ppb) of atrazine during embryonic development and then allowed them to mature with no additional chemical exposure.
Zebrafish exposed to concentrations of 3 and 30 ppb showed significant increases in progesterone levels, with the 30 ppb group also exhibiting a decrease in spawning and a significant increase in the breakdown of the ovarian follicles. The researchers observed physical changes in offspring, including a decrease in the head length to body ratio in the 30 ppb group and a significant increase in ratio of head width to body in the 0.3 and 3 ppb groups. The researchers also found alterations in genes associated with endocrine system development and function, tissue development, and behavior. The new findings suggest a developmental origin of reproductive dysfunction in adult zebrafish caused by embryonic atrazine exposure.
Citation: Wirbisky SE, Weber GJ, Sepúlveda MS, Lin TL, Jannasch AS, Freeman JL. 2016. An embryonic atrazine exposure results in reproductive dysfunction in adult zebrafish and morphological alterations in their offspring. Sci Rep 6:21337.