Arsenic – Making the Invisible, Visible!

What is the Number ONE Toxic Substance in the US? Here’s a hint: detection of contamination with this substance even at fatally high levels remains problematic because it is tasteless, colorless, and odorless.  

According to the CDC and the ATSDR (Agency for Toxic Substances and Disease Registry) arsenic is the number one toxicant Americans are both most likely to be exposed to and most likely to be made sick or die as a result of the exposure. In the case of arsenic, the exposure sources are drinking water and food.  

The ATSDR ranks chemicals using an algorithm that transforms potential public health hazards into a points-scaled system based on two things:  

1. frequency of occurrence at National Priority List (NPL) Superfund sites 

2. toxicity and potential for human exposure.  

Arsenic tops the list in spite of the fact that this ranking doesn’t even include common sources of exposure from drinking water, food, preserved wood exposure (also called copper-chromated arsenic-treated wood), coal- and wood-burning stoves, and arsenical pesticides.  

Arsenic is considered a human carcinogen and is known to cause common cancers of the skin (squamous and basal cell), bladder, lung, kidney, nasal passages, liver and prostate cancer. Non-cancerous effects include cardiovascular and pulmonary disease, immunological, neurological and endocrine-disruption effects.  

Arsenic in drinking water has long been a simmering problem in the U.S. In 2001, the EPA asked the National Academy of Sciences to examine the cancer risk for arsenic in drinking water. At that time the regulatory maximum contaminant level (MCL) was 50 ppb, which was originally set in 1948.  

The NAS committee found that men and women who daily consume water containing 3 ppb of arsenic have about a 1 in 1,000 increased risk of developing bladder or lung cancer during their lifetime. At 5 pbb, the risk is about 1.5 in 1,000; at 10 ppb, it is greater than 3 in 1,000; and at 20 ppb, it is close to 7 in 1,000. Given that the maximum target cancer risk the EPA uses for drinking water contaminants is a risk of 1 in 1 million individuals, the recommendation in line with those regulations would have been approximately 3,000 times less than the standard of 10 ppb. 

Yet, not surprisingly, the EPA decided, based on the “required cost-benefit provisions” and in the face of substantial political pressure, to set (and has stuck with) a 10 ppb standard. You can do the math here - a 3 in 1,000 risk for cancer = 331,002,651/1000 x 3 = 993,000 lifetime cases of cancer in the U.S. caused by drinking water at the current allowable level of arsenic. The EPA’s maximum contaminant level goal (MCLG) is zero, but unfortunately not enforceable. By the way, the same is true for lead in drinking water (an MCLG of zero) -just in case you thought the 15 ppb level of lead in drinking water was safe - the MCLG usually tells the real story.  

As a result of the original NAS research, other countries and some states have set their own standards: the Netherlands has established a regulatory limit of 1 ppb in drinking water. Denmark, New Hampshire, and New Jersey, have all established a regulatory standard of 5 ppb. 

Even though this new insufficient standard was set In 2001, and was intended to be enforced by 2006, many public water systems have remained in violation of the arsenic rule up until the present when as many as 400,000 individuals may still be drinking water with arsenic levels over the 10 ppb limit.  

A new study, by a team at the Columbia University Mailman School of Public Health, and led by one of our upcoming EHS 2021 speakers, has reframed this problem. 

“Inequalities in Public Water Arsenic Concentrations in Counties and Community Water Systems across the United States, 2006–2011” was published last month in Environmental Health Perspectives.   

The study results showed that there are still close to 500 counties in the U.S. whose arsenic levels exceed the current EPA regulation for 10 ppb. “It's a great health concern”, said Ann Nigra, lead author of the study, “because there is no safe level of arsenic in drinking water." (According to the EPA, CDC, and ATSDR, the same is true for lead levels in drinking water and children’s blood.) 

And the situation is even worse for those who drink out of private wells.  Arsenic concentrations in drinking water from some private wells in the United States are as high as 3,100 μg/L, which is in the range of the highest concentrations reported in Bangladesh, where the WHO refers to arsenic in well water of the Bangladeshis as “the largest mass poisoning of a population in history”.  

Prior research has also shown that large areas in the southwestern US have elevated arsenic in the aquifer: a 2012 study indicated that 42.7% of the area of aquifers in the southwestern United States have arsenic concentrations of ≥ 10 μg/L.  

But it’s not just the southwest: out of 63,000 wells tested in North Carolina, 1,436 (2.3%) had arsenic concentrations of > 10 μg/L with a maximum arsenic level of 806 μg/L. 

The Columbia researchers looked at the available EPA database for 13 million records from 2006 to 2011 covering 139,000 public water systems in 46 states, Washington D.C., and Native American tribes. The records cover water service for 290 million people, representing 95 percent of all public water systems and 92 percent of the total population served by public water systems.  

They created an interactive map for all the counties in the US with public drinking water arsenic levels reported between 2006 and 2011. This map doesn’t include data for the states of Colorado, Delaware, Georgia, Mississippi or the U.S. EPA Regions 2, 6, 7, and 10 for water systems serving American Indian tribes because the states or the EPA failed to submit data for the voluntary reporting system called the “3rd  Six-Year-Review (SYR3)”. Unfortunately, Colorado, Mississippi and  the U.S. EPA  reporting for tribal public water systems in those regions had significantly higher arsenic violation rates previously.  

And speaking of violation rates, the stunning work by the research team in this study is revealed in two separate maps:  

The first is a map, by county, of the public water systems that were in or out of compliance with the 10 ppb arsenic Rule. Low refers to low arsenic levels and high refers to arsenic levels over 10 ppb (not in compliance with the Rule). High/low is out-of-compliance in 2006 but in compliance in 2011 and low/high is the opposite. What you can immediately see is that for the most part (with the exception of Nevada, Arizona, New Mexico, isolated counties in the Midwest, Texas, and possibly the non-reporting states) most counties are in compliance with the 10 ppb regulation. But.... 

let’s take a look at a more precautionary view, say below 1 ppb (1 mg/L), where the National Academy of Sciences calculated an arsenic level in drinking water cancer risk of only 1 in 5,000. This is still a very far statistical cry from 1 in 1x106  cancer risk  that the EPA uses for all other water-borne carcinogens. Here, we see a different story.   

This is an indication that we have some work to do. Remembering that “no level of arsenic in water is safe” it looks like the drinking water of most of the Western US and a significant portion of the Midwest, is problematic.  

Actions items? 

Take a look at your area using the interactive map the Columbia study provided and become intimately acquainted with municipal and local well water arsenic levels where you live and where your patients live.   

Learn how to test for arsenic in a patient’s spot urine (the appropriate test) and know the signs and symptoms of low-level arsenic exposure. (we have lectured on this at EHS previously and the NAEM has some good lectures in their Member Library). 

Most importantly, ask your patients if they use a water filter for cooking and drinking and what type? If you have high levels of arsenic in your drinking water, reverse osmosis, although the best technology for arsenic removal, does not guarantee elimination of arsenic, so water testing is suggested before AND after filtration is installed.  

And one of the global experts on low-level arsenic exposure, Dr. Ana Navas-Acien, (one of the authors of the  above Columbia study), will be speaking at EHS2021 on “The Current Role of Toxicant Metals in Health Outcomes: Assessment, Diagnosis and Treament. Dr. Navas-Acien has published prolifically in the area of arsenic exposure and investigated the role of low-level arsenic exposure in diabetes and cardiovascular disease here in the U.S. Recently she has collaborated with Dr. Tony Lamas the lead  in the TACT2 Trial to look at the effect of IV EDTA in the elimination of specific toxic metals in diabetics with cardiovascular disease and the risk for subsequent cardiovascular events.