Newswise — June 26, 2023-- A recent study conducted by Columbia University Mailman School of Public Health has revealed that there have been notable decreases in arsenic exposure among various segments of the U.S. population. Specifically, users of public water systems in the South and West regions, as well as Mexican American participants, experienced significant reductions in arsenic exposure. The study, published in the journal Environmental Pollution, also identified differences in the extent of these changes based on educational attainment, in addition to factors such as region, race/ethnicity, and the level of arsenic in public water sources.
Since its initial enforcement in 2006, the Final Arsenic Rule has successfully lowered the maximum contaminant level of arsenic in public water systems to 10 μg/L.
Maya Spaur, PhD, from the environmental health sciences department at Columbia Mailman School of Public Health, stated, "Our research indicates that implementing a stricter regulatory standard for arsenic in public water systems has effectively decreased arsenic exposure in numerous communities throughout the United States. We observed the greatest reductions in populations and regions with initially high levels of water arsenic exposure. These findings demonstrate the effectiveness of federal water regulations in reducing exposure among the most highly affected individuals."
By utilizing data from the 2003-2014 National Health and Nutrition Examination Survey (NHANES), the researchers conducted an assessment of arsenic exposure derived from water among populations dependent on public water systems. They employed a recalibration method on urinary dimethylarsinate (rDMA) to eliminate the effects of smoking and dietary factors. The study evaluated the average variances and the corresponding percentage reductions in urinary rDMA, comparing subsequent survey cycles with the baseline period of 2003-04. This evaluation was stratified based on factors such as region, race/ethnicity, educational attainment, and the concentration of water arsenic at the county level.
When comparing the years 2013-14 to 2003-04, participants with the highest levels of arsenic in Community Water Systems (CWS) experienced a 9% reduction in urine rDMA, equivalent to 0.32 μg/L. The most significant declines in urinary rDMA were observed in regions with elevated water arsenic levels, particularly the South (16% reduction, equivalent to 0.57 μg/L) and the West (14% reduction, equivalent to 0.46 μg/L). Among different racial and ethnic groups, the largest and statistically significant reductions in urinary rDMA levels were observed among Mexican American participants (26% reduction, equivalent to 0.99 μg/L) and Non-Hispanic White participants (10% reduction, equivalent to 0.25 μg/L).
Exposure to arsenic over a long period, even at low or moderate levels, can heighten the risk of cancer and other chronic diseases. The U.S. Department of Health and Human Services Agency for Toxic Substances and Disease Registry recognizes arsenic as a human carcinogen and toxic substance associated with various detrimental health outcomes. In fact, it holds the top position on their substance priority list. The U.S. Environmental Protection Agency (EPA) is responsible for regulating arsenic in public drinking water supplies and determining the maximum contaminant level (MCL) permissible in public water systems. The MCL takes into account factors such as technological feasibility, financial considerations, and public health implications.
In 2006, the EPA lowered the maximum contaminant level (MCL) of arsenic in public water systems from 50 µg/L to 10 µg/L. However, it is important to note that there is no recognized safe level of exposure to inorganic arsenic. In light of this, the EPA established a health-based MCL goal (MCLG) of 0 µg/L. Maya Spaur commented, "While the current MCL represents a significant reduction compared to the previous standard, it is still considerably higher than the MCLs implemented in New Jersey, New Hampshire, Denmark, and the Netherlands."
Spaur emphasized the need for further endeavors to address the persisting disparities in Community Water System (CWS) arsenic exposure.
Anne E. Nigra, senior author and assistant professor of environmental health sciences at Columbia Mailman School of Public Health, stressed the importance of future regulatory measures and the provision of managerial, financial, and technological support to communities where public water systems still exhibit elevated levels of arsenic. The objective is to tackle the ongoing disparities in drinking water quality. Nigra added that their study underscores the vital role of federal drinking water regulations in advancing environmental equity and justice.
Co-authors are Benjamin Bostick and Steven Chillrud, Lamont-Doherty Earth Observatory, Columbia; and Pam Factor-Litvak, Ana Navas-Acien and Anne E. Nigra, Columbia Public Health.
The study was supported by the National Institute of Environmental Health Sciences, grants F31ES034284, P42ES010349 and P30ES009089, and by the NIH National Institute of Dental & Craniofacial Research, grant DP5OD031849.
Columbia University Mailman School of Public Health
Founded in 1922, the Columbia University Mailman School of Public Health pursues an agenda of research, education, and service to address the critical and complex public health issues affecting New Yorkers, the nation and the world. The Columbia Mailman School is the fourth largest recipient of NIH grants among schools of public health. Its nearly 300 multi-disciplinary faculty members work in more than 100 countries around the world, addressing such issues as preventing infectious and chronic diseases, environmental health, maternal and child health, health policy, climate change and health, and public health preparedness. It is a leader in public health education with more than 1,300 graduate students from 55 nations pursuing a variety of master’s and doctoral degree programs. The Columbia Mailman School is also home to numerous world-renowned research centers, including ICAP and the Center for Infection and Immunity. For more information, please visit www.publichealth.columbia.edu
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