Arsenic in drinking water may increase the risk of preterm birth

Preterm birth, when a baby is born before 37 weeks, is a pressing public health problem because babies born early have greater risks of mortality and health complications and later disease in child and adulthood. In 2017 alone, California had more than 400,000 preterm births an increased rate of 8.6%compared to the previous year.

Though we know that genetic factors, exposures to chemicals including air pollutants, and social factors such as and race and poverty can all raise preterm birth risk, there’s a lot we still don’t know about the causes of preterm birth—especially when it comes to environmental and social stressors. We do know that pregnant women in California are exposed to multiple environmental pollutants from air, food, water and consumer products. We also know that pregnant women can experience social stress due to factors such poverty, food insecurity and discrimination.

So in our new study, we set out to investigate the relationship between preterm birth and cumulative burdens of multiple environmental exposure and social stressors. We used a novel integrative big data approach to link two large datasets—1.8 million California birth records with environmental exposure information from CalEnviroScreen, a database that contains thousands of data points on environmental pollution and social factors for every census tract in California. By leveraging large datasets, we were able to reveal new, and surprising, patterns.

We found that arsenic pollution in drinking water is significantly associated with an increase in preterm birth of 1%, by comparing preterm birth in populations with different levels of arsenic contamination in drinking water. This may seem very small, but because there are so many pregnant women exposed to arsenic in their drinking water, it can translate into sizeable population impacts.. In our study of almost 2 million births, most of the pregnant women are living in area with arsenic contamination in the drinking water. For example, if the preterm birth rate for population without arsenic exposure is 7.0%, our study suggests that the same population with arsenic exposure in drinking water will have 1% increase in preterm birth rate (7.07%), which is around 1400 additional preterm births across a population of 2 million because of arsenic in drinking water. This shows how a small increase in risk spread across many people can translate to big impacts.

An additional finding is that there are many people living in area where arsenic concentration in drinking water is higher than regulatory standard. For example, the U.S. EPA’s maximum contaminant levels (MCL) is 10 parts per billion (ppb), which suggests that many people living in those areas are at higher risks of arsenic exposure (shown in figure below).

Picture1
Source: Figure modified from Huang, et al., 2018.

U.S. EPA adopted this standard for arsenic in drinking water in 2001 with consideration for the various health effects associated with arsenic exposure, including “cancerous effects (skin, bladder, lung, kidney, nasal passages, liver and prostate) and non-cancerous effects: cardiovascular, pulmonary, immunological, neurological and endocrine (e.g., diabetes) effects”. While pregnant women exposed to arsenic in drinking water may have increased risk of preterm birth, the rest of the population may face different risks related to these other diseases.

In addition, we found that both environmental chemical exposures and social stressors such as PM2.5, nitrate in drinking water and neighborhood unemployment rate collectively are associated with increased risk of preterm birth. This study adds to the evidence that cumulative impacts of multiple environmental and social factors are associated with adverse health outcomes. Note that there are some limitations and assumptions made in this study. For example, given the design of the environmental database used, we assume constant pollution during the entire pregnancy, and therefore didn’t account for temporal variability.

The power of our study shows how data collected in California can be used to identify potential risk factors that deserve more attention in research, monitoring and efforts that prevent exposures to harmful pollutant levels in order to better improve prenatal health.


Other co-authors on this work include: Tracey J. Woodruff (UCSF), Rebecca J. Baer (UCSD), Komal Bangia (OEHHA), Laura M. August (OEHHA), Laura L. Jellife-Palowski (UCSF), Amy M. Padula (UCSF, senior author), Marina Sirota (UCSF, senior author).

Unsealing Science: UCSF’s Chemical Industry Documents Library

Why would the University of California San Francisco host internal industry emails, scientific studies, and public relations campaigns in its Industry Documents Library (IDL)?  Because UCSF is dedicated to producing and using the best science to benefit the public’s health – and if science is manipulated or misrepresented, that can result in negative effects. Documents in the IDL reveal industry thinking, strategizing, and operations on matters central to public health. Providing public access to otherwise-unavailable corporate records enforces corporate transparency, enriches public discussion, and ultimately ensures that accurate data and science inform decisions on health.

The UCSF Industry Documents Library, a digital archive of nearly 15 million internal tobacco, drug, and chemical industry documents are used by scientists, community advocates, journalists, policymakers, attorneys, and others in their efforts to improve and protect public health. Its flagship Truth Tobacco Industry Documents Library–founded in 2002 as the Legacy Tobacco Documents Library– has received more than 7 million visitors and has been instrumental in furthering tobacco control research and education for over a generation.  The research supported by the IDL has led to some of the most successful policy outcomes of the “tobacco wars,” by exposing, in their own words, what the tobacco industry knew about the health impacts of tobacco, when they knew it, and how industry covered up and distorted the available scientific evidence to enrich their deadly profits. The documents library underpins rigorous and scholarly research on influences and biases in science – which improves the basis of scientific findings and ultimately saves lives.

As of August 2018, more than 1,000 scholarly articles, news items, books, and other publications have been written using IDL documents as primary source material.  Tobacco industry documents have been used in:

  • Seminal books including The Cigarette Papers by Stanton Glantz and colleagues,  The Golden Holocaust by Robert Proctor and The Cigarette Century by Alan Brandt;
  • Playing with Fire, the Chicago Tribune’s expose on flame retardants;
  • The 2014 documentary Merchants of Doubt;
  • Submissions to the Tobacco Products Scientific Advisory Committee (TPSAC) for the FDA’s recommendations on menthol; and
  • The Center for International Environmental Law’s website Smoke & Fumes, which combines oil industry and tobacco industry documents to reveal connections between them.

UCSF’s Industry Documents collections are the result of the discovery process in litigation, public records requests, and whistle-blowers.  The documents are donated by lawyers, non-profit organizations, and private individuals.  Once a collection is accepted by the IDL, each document is optical character recognition (OCR) scanned to maximize search-ability and enhance research ease. The Library tags each document with metadata descriptors such as authors, people mentioned, date written and acquired for each document, and document type (e.g., deposition, email, memo), allowing researchers and users to access the documents and cross-reference them easily with the public record and other databases. Researchers are able to search within one industry archive, or across all industry archives at once, facilitating evaluation of connections and threads of research.

Housing these documents at UCSF provides a protected but public archive for the documents.  Industries known for subverting science and manipulating public knowledge are unable to tamper with documents that once fully evaluated and contextualized may be acted upon to promote public safety.  The UCSF Library also creates a portal where researchers can search for and access the documents most relevant for their research, rather than having to rely on private companies and search engines that return sub-optimal results because they are not tailored for research purposes. Other users can easily build on previous research because the Library’s format makes citations reliable and accessible for future use. Curating the documents, highlighting documents new to the collection, collecting peer-reviewed research on the documents, and communicating to the public about the database further work to preserve the documents as a democratic commons and academic resource.

Three new collections are in the process of being added to the Chemical Industry Documents Library: the Benzene Collection; the Glyphosate and Agrochemical Collection; and the Poison Papers.  On September 13, 2018, the UCSF Environmental Health Initiative, in collaboration with the UCSF Program on Reproductive Health and the Environment and the UCSF Industry Documents Library, will host two timely and important events, open to the public, on the science and stories contained within these documents. Donors of the collections will discuss what the documents mean for public health and the challenges they faced to make them available to the public.  While these collections are recently added and not yet fully explored by researchers, they promise to advance our understanding of the relationship between the chemical industry and public health much in the same way we learned about tobacco.  To register for the event, please click here.

The Chemical Industry Documents Library has been developed in partnership with UCSF’s Environmental Health Initiative with a grant from the Marisla Foundation and the generous support of Rachel’s Network.


AMC picAnnemarie Charlesworth, MA is the Associate Director of the Environmental Health Initiative (EHI) and Director of the Clinical Outreach and Translation team of the UCSF Program on Reproductive Health and the Environment (PRHE).  She brings over 15 years of program evaluation, design and implementation expertise to the EHI.
YogiYogi Hale Hendlin, PhD, is a postdoctoral research fellow in the Center for Tobacco Control Research and Education, and works on the social and environmental determinants of health arising from industry-created epidemics.

EPA method will curtail science used in chemical evaluations

EPA recently released its new TSCA “systematic review” method that establishes how the Agency will use science to make decisions about whether to limit toxic chemicals in our air, water, food and everyday products. Unfortunately, our analysis finds that instead of ensuring a comprehensive, unbiased evaluation, like a systematic review is supposed to do, the TSCA method will severely narrow the science the Agency considers, leading to poor decisions and putting the public’s health at risk.

The method lays out the ‘rules’ EPA will use to find, assemble and interpret scientific evidence on chemical hazards and health effects. What studies EPA considers, and how EPA evaluates those studies can change the final conclusion about whether or not a chemical poses risks. Thus the ‘rules’ have profound implications for public health– especially for populations like pregnant women and children who are more vulnerable to chemical exposures. In particular, a serious concern with the TSCA approach is that it will result in relevant, high-quality studies being excluded from the Agency’s consideration.

Systematic review methods (such as Cochrane) are the standard for evidence evaluation in clinical medicine because they are demonstrated to save lives and money by providing a comprehensive, unbiased evaluation of the scientific evidence. Building from the clinical sciences, there are established, empirically-based methods for systematic review in the environmental health sciences that are validated, peer-reviewed and demonstrated in case studies over the last decade. These include the National Toxicology Program’s OHAT method and the Navigation Guide, developed here at UCSF. Of course we think the Navigation Guide is pretty great, but don’t take our word for it—the National Academy of Sciences (NAS) reviewed both methods and found them to be scientifically robust and exemplary of the type of systematic review method EPA should utilize in chemical evaluations.

What is particularly dismaying about the TSCA method is that it ignores the best practices for systematic review that have already been rigorously tested and validated– a waste of money and time. It is inconsistent with all the current methods for systematic review, which are informed by decades of research and development; the TSCA method is a far departure from OHAT, the Navigation Guide, and the recommended NAS approach.

First, the TSCA method is incomplete- it covers 2 of the 9 required steps, as shown in the diagram. An especially critical missing step is “Develop protocols for systematic review” which must occur prior to identifying and evaluating the evidence to ensure an unbiased review. Further, EPA’s regulation for risk evaluations also requires this—it mandates that the Agency use “a pre-established protocol” to conduct assessments.

Blog figure
Adapted from The National Academies Press (2014) Review of the EPA’s IRIS Process

Second, the TSCA systematic review method sets up an unscientific ‘scoring’ scheme for evaluating study quality by assigning numerical scores to various study components, such as exposure characterization, and then calculating an overall “quality score.” The NAS, Cochrane methodology, and the academic community have already found based on analysis of empirical data that this type of ‘scoring’ approach does not measure actual study quality, and can lead to biased, inaccurate results. Further, EPA has chosen to score numerous study components that have nothing to do with the quality of the underlying research, such as how completely the authors reported the methods used to carry out the study.

Even worse, the TSCA method then uses this scoring scheme to inappropriately exclude studies based on a single reporting or methodological limitation, saying these studies are ‘unacceptable for use.’ The TSCA method’s arbitrary, unscientific scoring and exclusion of studies is right in line with other attempts to restrict the science EPA relies on, such as the recent “censored science” proposal from former Administrator Pruitt. And, we have a preview of how application of the TSCA method will throw out science—EPA applied the TSCA method in its evaluations of persistent, bioaccumulative and toxic chemicals, resulting in exclusion of almost 500 studies because they “did not meet evaluation criteria.” Excluding relevant studies can only result in a biased evaluation and inaccurate conclusions.

The point of a systematic review is to evaluate the entire body of scientific evidence, not exclude relevant science— no valid systematic review method excludes studies in this way and the TSCA method is far outside the scientific mainstream in this and many other respects. EPA needs to scrap the TSCA method and employ an existing empirically-based method (such as OHAT or Navigation Guide) that has already been tested and approved by the NAS. True systematic reviews are comprehensive, transparent, and unbiased and would help the Agency make the best science-based decisions to ensure protection of the environment and human health.


This post was co-written by Veena Singla, PhD, Associate Director of Science & Policy at PRHE. Public comments on EPA’s TSCA systematic review method were written by Patrice Sutton, MPH, Research Scientist at PRHE.