The Environmental Quality Institute

Arsenic

Although its acute and chronic toxicity properties have been recognized for over a century, recent studies have definitively confirmed that arsenic (As) is a far more powerful human carcinogen than previously suspected. These findings have been repeatedly confirmed since about 1996 and have vastly increased the concern in the medical, scientific, public health, and environmental regulation community. A study performed in the fall of 2001 by the National Academy of Sciences found the excess lifetime risk of lung or bladder cancer from drinking water at the current standard of 10 ug /L to be more than 3 cases per 1,000 individuals. The standards for other known or suspected human carcinogens, such as benzene, tetrachloroethylene, DDT, PCBs, etc., are set at a one cancer case per million population risk level (1/106). Thus, the risk from regularly drinking water at the current standard for arsenic is more than 3,000 times the cancer risk associated at the standard for most environmental toxins.

Our Studies

The two most significant routes of exposure of the public to arsenic are through drinking water and Chromated Copper Arsenate (CCA) pressure-treated lumber. EQI conducted national studies of public exposure to arsenic from CCA pressure-treated lumber, surrounding soil, and water. In addition to adding to our knowledge about the risk from these routes of exposure, the research allowed participants to take advantage of low-cost ($18-$20) testing of their (CCA) pressure-treated lumber, soil, and water through our collaborating non-profit organizations, the Environmental Working Group, and Clean Water Lead Testing.

 

Arsenic in CCA Pressure-Treated Lumber

Arsenic in pressure-treated deckingLumber that is treated with chromated copper arsenate to resist insect and fungal decay has been used extensively world-wide in outdoor structures for nearly three decades. It was recognized from the onset that arsenic would be leached from the wood over time resulting in some level of either relatively direct exposure from skin contact, or from more indirect exposure from arsenic in soil, groundwater, or surface water contamination. While arsenic was already a well recognized toxin with various chronic health effects even from low level exposure (e.g., skin lesions, cardiovascular effects, lung, skin, bladder, kidney, and liver cancers), during the mid-1990's epidemiological evidence began to surface which indicated that arsenic was a far more powerful bladder, lung and kidney carcinogen than previously believed.

A study published in 2005 by Yang et al. examined bladder cancer mortality ratios in Taiwan from 1971-2000; the researchers found a decrease in bladder cancer mortality after the drinking water system was improved to remove arsenic. A similar study by the same authors in 2004 found a decrease in lung cancer mortality based on the same drinking water improvements. These studies strengthen the causal relationship between arsenic and bladder and lung cancers.

The cancer risk estimates for arsenic exposure from pressure-treated lumber vary among studies. Roberts and Ochoa estimate 502 per million population for skin cancer only; Gradient Corporation estimates 1 per million population for skin cancer only; Sharp et al. estimate 2000 per million population for lung and bladder cancer; the US Consumer Products Safety Commission estimates between 2 and 100 cases of lung/bladder cancer per million population; The USEPA estimates 23 cases of lung/bladder cancer per million population in a warm climate and 11 cases in a cold climate.

In response to these findings, many countries including the United States, the entire European Union, Japan and Canada have either discontinued or announced decisions to phase out production of CCA-treated lumber for residential uses by mid-2004.

EQI worked with the Environmental Working Group to conduct a national study on arsenic dislodgement from CCA lumber. As part of the project, arsenic levels were statistically related to variables such as in-service age, geographic location, percent sunlight exposure, and treatment/sealant history. In a preliminary study published in the New Zealand Journal of Chemistry, researchers at EQI found from a survey using wipes of US households with CCA pressure-treated lumber that the mean arsenic wipe transfer calculated across all surface types, service ages, geographic areas, and treatment types, is 63.6 g/100 cm 2, with a median of 12.5 g/100 cm 2. It was found that there are higher levels of arsenic associated with samples taken from the northwest, samples taken from locations receiving more sun, and samples recently treated with water-sealant, paint, stain, or other covering. It was also found that water-sealants appear to work for approximately 6 months while other treatments may be effective for two years or more.

Part of this study involved the conversion of the average amount of arsenic from the survey into what would be expected to occur if a hand contacted the surface instead of a wipe. Excess risk for lung or bladder cancer was then calculated using a methodology similar to the CPSC approach for persons under various scenarios of contact with CCA lumber. For a toddler from the ages of 6 months to 18 months, we estimated the risk to be 6.6 cases per 10,000. For a young child from the ages of 3 years to 6 years, we estimated the risk to be 7.2 cases per 10,000. For an older child from the ages of 7 years to 13 years, we estimated the excess risk to be 1.6 cases per 10,000, and for an adult, we estimated the risk to be 1 case per 10,000.

As part of this study, conducted in collaboration with the Environmental Working Group, individuals received a low-cost test of their lumber or soil and a letter explaining their results. In addition to providing the participant with information that can be used to reduce their individual arsenic risk, it also helped us to better understand the complex phenomenon of the risk from arsenic due to exposure to CCA lumber.

EQI has conducted research projects on the effectiveness of various experimental lumber treatments in preventing the leaching of arsenic from CCA lumber, and also on the efficacy development of alternative lumber preservatives. A grant from the Environmental Protection Agency enabled EQI to examine the amount of arsenic that may be transferred indoor to carpet surfaces after walking across a CCA-treated lumber deck.

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Arsenic in Drinking Water

Arsenic in pressure-treated deckingArsenic contamination usually occurs in ground (i.e., well) water rather than surface water (stream or reservoir) supplies, due to weathering of deep underground rock, gravel or sandy soils. While there has probably always been some significant background "natural" risk from arsenic in US water supplies, it is only in the last half-century that wells have been bored hundreds of feet into deeper groundwater aquifers. Also, there is the plausible, but as of yet unproven, theory that the oxidation and subsequent arsenic release from aquifer rock, gravel and finer particle fractions is accelerated when private or municipal drinking water wells are pumped intensively, causing a drawn-down zone around the well where air (i.e., oxygen) can periodically and frequently reach previously saturated subsurface rock strata.

Arsenic can cause several negative health effects including thickening and discoloration of the skin, stomach pain, nausea, vomiting, diarrhea, numbness in the hands and feet, partial paralysis, and blindness. Most notably, arsenic has been linked to cancer of the skin, bladder, and lungs, as well as kidney, liver, and prostate cancer. Although its acute and chronic toxicity properties have been recognized for over a century, very recent studies have definitively confirmed that Arsenic (As) is a far more powerful human carcinogen than previously suspected. These findings have been repeatedly confirmed since about 1996 and have vastly increased the concern in the medical, scientific, public health, and environmental regulation community.

A study published in 2005 by Yang et al. examined bladder cancer mortality rations in Taiwan from 1971-2000; the researchers found a decrease in bladder cancer mortality after the drinking water system was improved to remove arsenic. A similar study by the same authors in 2004 found a decrease in lung cancer mortality based on the same drinking water improvements. These studies strengthen the causal relationship between arsenic and bladder and lung cancers.

In the fall of 2001, the National Academy of Sciences issued an updated report on the risks from arsenic in drinking water and estimated the excess lifetime risk of bladder cancer to be 1 excess case per 1000 at an arsenic concentration of 3 ug /L, 1.5 extra cases per 1000 at a concentration of 5 ug /L, more than 3 extra cases at a concentration of 10 ug /L and 7 extra cases per 1000 at a concentration of 20 ug /L. The issue is complicated by the fact that very few commercial drinking water compliance laboratories can detect arsenic at levels below 2 ug /L, and many have 3 to 5 ug /L as their reportable detection limit. Thus, many commercial laboratories are not able to reliably quantify arsenic at 3 ug /L, a level equated with a risk that is 1,000 times higher than the risk used to set standards for most environmental toxins.

The Safe Drinking Water Act amendments of 1996 required the EPA to revise the existing drinking water standard of 50 ug /L of arsenic. In the fall of 2000, EPA determined from their review of over a dozen recent studies that the current Safe Drinking Water Act arsenic standard of 50 ug /L represents a 1/400 or 2,500 cases-per-million lifetime cancer risk. The standards for other known or suspected human carcinogens, such as benzene, tetrachloroethylene, DDT, PCBs, etc., are set at a one cancer case per million population risk level (1/106). EPA reduced the US drinking water standard down to a level of 10 ug /L in January of 2001. The compliance date for this standard was set for January 23, 2006. The EPA estimates that 13 million Americans will be protected by the new lower standard, though the agency also estimates that 15% of Americans have their own private drinking water systems, which are not subject to EPA standards.

The EPA estimates that about 5 percent of US public groundwater systems have concentrations exceeding the 10 ug /L arsenic standard and about 12 percent have concentrations exceeding 5 ug /L. Because nearly all certified commercial laboratories who conduct the compliance arsenic analyses for these thousands of public water systems have detection limits of between 2 and 5 ug /L, very little is known about how large a percentage of the US population is exposed to 2 to 5 ug /L, and virtually nothing is known about the number of Americans exposed to arsenic drinking water levels in the 0.2 to 2 ug /L which still represents an extremely significant public health threat. Consider EPA's estimate that 5 percent of groundwater systems (i.e., about six million people) have at least 10 ug /L As. This translates to more than 18,000 extra cancer cases just within this population segment; for the approximate additional eight million people drinking water with arsenic levels between 5 and 10 ug /L (mean = 7.5 ug /L), this represents approximately another 12,000 cancer cases. Thousands more cases are attributable to the even larger population segment exposed to lower arsenic concentrations.

In recognition and response to the public health threat now recognized from arsenic contamination of groundwater, EQI launched a nationwide study to determine the geographic dynamics of the well water arsenic problem. The study was funded by the Clean Water Fund of North Carolina and used low detection limit arsenic data from thousands of households on public, private, community, and individual well water systems to determine risks on a geographic basis, and equally importantly, to determine the true prevalence of various degrees of arsenic contamination in the US well water supply system.

The relatively scant information available from previous studies and surveys indicate that arsenic "hot spots" can occur almost anywhere in the US, but that the general prevalence of problems is greater in the more arid portions of the country. However, because the cancer risk is so great, even at what were until recently believed to be inconsequential levels, everyone on any type of groundwater supply would be wise to get their water tested for arsenic at as low a detection level as possible.

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