Christina Tyler, a biomedical sciences graduate student, has developed a model using mice to measure the negative effects of exposure to arsenic, and has studied means of countering those effects.
Tyler’s pregnant mice were given water that contained 50 parts per billion of arsenic — the same levels consumed by the average American prior to 2006. After being born, the baby mice were given a separate cage with clean drinking water, she said.
All of the arsenic-exposed baby mice showed signs of depression, lethargy and trouble with memory, she said.
“The scary part about it is that these offspring are not directly drinking the water with arsenic; it is just their moms,” Tyler said. “For people like us, who were born way before 2006, our moms drank it and then we drink it, and we have now just started going down to that 10 parts per billion.”
In 2002, regulators ruled that the proportion of arsenic in drinking water could not exceed 10 parts per billion. This standard went into effect in 2006, according to the official website of the Environmental Protection Agency. Prior to 2006, arsenic was considered to be safe in water sources up to 50 parts per billion.
Another UNM graduate student had previously determined that mice exposed to arsenic exhibit learning memory deficits and depressive behaviors. Tyler built on this work to determine how those effects could be reversed, she said.
She said she thought arsenic was reducing the brains’ ability to make new cells in the hippocampus — a process known as neurogenesis — which was causing the deficits in the mice. Her theory held throughout testing, she said.
“The hippocampus is one part of the brain important for learning and memory,” Tyler said. “There is continual division of cells in the brain. The hippocampus can make new cells, and this process is called adult neurogenesis. People who have depression tend to have reduced neurogenesis.”
Tyler said she then gave the mice Prozac for a month and tested their behaviors. The mice responded well and showed fewer signs of depression. Further, mice placed in an enriched environment without Prozac responded just as well.
“(The mice) go to a cage with a lot of other mice and they have toys and a lot of other things to interact with. It provides novelty and increased social interaction,” she said. “This experience in enrichment actually produced the same outcome of increased adult neurogenesis as the Prozac did.”
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She said the study was important in the context of New Mexico, where people have been exposed to higher proportions of arsenic relative to other states. New Mexico has created a state arsenic compliance strategy to assist water systems impacted by the element. However, sometimes removing arsenic from water can be difficult.
“A lot of people in New Mexico live in rural areas and they have well water, and there can be higher amounts of arsenic in well water,” Tyler said. “When EPA did their 10 parts per billion standard, Albuquerque had a hard time coming into compliance with that. It takes a lot of resources and infrastructure to purify water like that.”
Arsenic occurs naturally in the groundwater in many locations and public water systems around New Mexico, according to officials of the Environment Department’s Drinking Water Bureau.
Based on work done across the world on arsenic’s relationship to cognitive deficits, Tyler’s team constructed a model because they were interested in the effects of arsenic exposure on development, she said.
Sayyed Shah is the assistant news editor at the Daily Lobo. He can be contacted at assistant-news@dailylobo.com or Twitter @mianfawadshah.
