UPPSALA, Sweden, Feb. 16 (UPI) -- A pharmaceutical progestogen released into the environment can lead to sterility in frogs, Swedish researchers at Uppsala University reported Wednesday.
The study, published in the scientific journal Aquatic Toxicology, indicated female tadpoles swimming in water containing the progestogen levonorgestrel are subject to abnormal ovarian and oviduct development, resulting in adult sterility, the university said in a release.
Many medicines consumed by people are released into the environment through sewage systems and different kinds of progestogens -- hormonal preparations usually prescribed for contraceptives, cancer treatment and to ease menopausal discomfort in women -- have been identified in waterways in a number of countries.
Uppsala University associate professor Cecilia Berg and doctoral student Moa Kvarnryd in the Department of Environmental Toxicology showed that levonorgestrel can cause sterility in female frogs at concentrations not much higher than those normally measured in the environment. The research group is part of MistraPharma, one of the largest global research networks focusing on pharmaceuticals and the environment.
Female tadpoles in water containing low concentrations of levonorgestrel showed a greater proportion of immature ovarian egg cells and lacked oviducts, entailing sterility, the university said. The frog's reproductive organs begin developing in the tadpole stage.
The findings show the importance of studying how pharmaceuticals affect animals in the environment, researchers said.
"The findings represent important initial evidence that an environmental progestogen can adversely affect frogs," Berg said. "Our findings show that pharmaceuticals other than estrogen can cause permanent damage to aquatic animals exposed during early life stages."