CHAMPAIGN, Ill. — Chemical disinfection makes water from natural springs and waste water drinkable; however, the process also creates by-products, not all of which are understood or regulated. A new study by researchers at the University of Illinois at Urbana-Champaign has found that a byproduct disrupts brain hormones that regulate the female reproductive cycle in mice and also damages cells in the brain. pituitary.
Iodoacetic acid, or IAA, is created when an oxidizing disinfectant such as chlorine reacts with iodide naturally present in water, the study leader said. Lori Raetzman, Professor of Molecular and Integrative Physiology. The findings of the new study on the effects of IAA on the regulation of reproduction in the brain complement the study co-author’s previous work Jodi’s flawsprofessor of comparative biosciences, who found that IAA also disrupts function and causes damage to ovarian cells, indicating that the chemical could impact the entire reproductive system.
“We know we need to sanitize the water, but the water that comes out of our taps isn’t pure – regulators only filter things they know about. Water regulators don’t have researched for IAA,” Raetzman said. “This study contributes to the growing body of evidence that suggests IAA may impact reproduction, so it might be reasonable to have screening for that as well, and to establish a safe level for that.”
In the new study, published in the journal Toxicological sciences, the researchers gave mice drinking water containing IAA at levels comparable to possible human exposure, as well as a control group of mice who received water without IAA, for 35 to 40 days. Next, they measured the production of reproductive regulatory factors in two key parts of the neuroendocrine system – the hypothalamus and the pituitary gland.
“Mice are often used as models for the human reproductive system because they have estrous cycles similar to human menstrual cycles,” said graduate student Rachel Gonzalez, the study’s first author. “The hypothalamus and the pituitary are the main regulators of the endocrine system. It is a good basis to say that a human being exposed to a certain amount of IAA could potentially have similar effects.
The researchers found that even at low levels, IAA disrupted the production of a key reproductive regulating factor in the hypothalamus. At higher levels, IAA reduced pituitary production of follicle-stimulating hormone, a key hormone in promoting egg maturation in the ovaries leading to ovulation. The hormone is also linked to the production of estrogen.
“Theoretically, a persistent reduction in follicle-stimulating hormone over the long term could potentially cause a problem with the development of follicles in the ovaries, which house eggs and release them during ovulation,” Gonzalez said. “In their study of effects on the ovaries, our colleague from the Flaws lab found problems with folliculogenesis in cell cultures. This work therefore shows that IAA can affect the entire reproductive axis.”
Additionally, researchers found toxic effects, including DNA damage, in the pituitary glands of mice that consumed IAA. Because of this discovery and previous findings from the Flaws lab regarding damage to ovarian cells, researchers are now studying if and how exposure of pregnant mice to IAA in drinking water affects their offspring.
“These chemicals will cause breaks in the DNA which, if not repaired properly, could lead to mutations in the DNA which would spread and could lead to further dysfunction – either tissue dysfunction because cells do not not working properly or diseases like cancer,” Raetzman said. “Part of the significance of that is that DNA damage can be passed down from generation to generation, so if mom’s eggs are damaged, they can transmit DNA damage to offspring.”
Researchers hope that continued study of IAA’s effects on neuroendocrine and ovarian aspects of the female reproductive system can help establish a safe level of exposure to guide future regulations, Raetzman said.
The National Institutes of Health supported this work.
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