Arsenic exposure associated with shorter telomere length in children
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Elevated arsenic in drinking water is endemic in the nation of Bangladesh. SPH’s Maria Argos, PhD, associate professor of epidemiology, has shown how exposure impacts maternal and child health, but her new research examines arsenic’s effects on aging.
Published in the journal Environment International, her senior authored article indicates chronic arsenic exposure may be related to the shortening of telomeres, the segments of DNA found at the ends of chromosomes that protect the loss of information from the chromosome as the cell replicates. Early childhood is a critical period for telomere biology, and early decreases in telomere length may lead to premature aging and heightened risk for diseases such as cancer or cardiovascular disease.
“We know there are very dramatic changes that happen to telomeres within the first five years of life,” Argos said. “Exposure during this sensitive period may be more representative of [the effects of arsenic] on telomere length as opposed to studying this in adulthood.”
Previous studies have largely focused on adults or children at birth using cord blood to study prenatal exposures. This study focused on about 500 children, aged five to seven years, residing in rural regions of Bangladesh with known exposure to arsenic through drinking water. Their exposure was likely to occur chronically from prenatal periods through early childhood. Urine samples indicated an inverse relationship between arsenic concentration and relative telomere length.
Argos and fellow researchers are also examining the effects of other metals exposures. They are analyzing toenail clippings from this cohort of children to measure exposure to several toxic metals, which may also drive the shortening of telomeres.
An emerging area of study is focused on environmental mixture effects, when a person might be exposed to numerous toxic metals over a period of time. At this point, Argos says the relationship between metal mixture effects and telomere length is unknown, but she notes that arsenic is the predominant and overwhelming exposure in many rural communities across Bangladesh.
Intervention strategies include encouraging switching to wells with known lower levels of arsenic, widespread testing of water sources, and educational campaigns on the health hazards of drinking water with elevated arsenic. However, Argos says the cost of installing new wells is very low, and the number of new wells across Bangladesh has increased dramatically since the year 2000. Many of these wells are installed without being tested.
“The idea here is that exposures we face early in life could have long-term health implications for us,” Argos said. “This potentially could be one mechanism that explains adverse health effects much later in life.”