Dangerous level of arsenic in water supply
By LINCOLN LOEHR
Water quality standards applicable in Washington State include human health standards adopted for the state by EPA in 1992 under the National Toxics Rule. For carcinogens, these are set at the hypothetical 1 in a million lifetime risk level.
The arsenic standard to protect those who consume the water and who also consume organisms that live in the water is 0.018 parts per billion (ppb). This is applicable to freshwater. The standard to protect those who only consume the organisms that live in the water is 0.14 ppb and is applicable in salt water.
A recent analysis of six public drinking water supplies in western Washington detected arsenic levels substantially exceeding the applicable human health water quality standard. The samples exceeded the 0.018 ppb standard by as little as a factor of 2 to as much as 900 times the standard. Future analysis of additional samples will extend this range. None of the samples analyzed met the human health standard.
Does this mean we should avoid drinking tap water and switch to bottled water?
No! Only one of the six measurements were of a tap water supply (Seattle's). The other samples were from five different brands of bottled waters (which shall mercifully remain nameless here). The tap water supply had one of the lowest arsenic levels measured.
The bottled water brands all touted their natural purity and goodness because of their long time in the earth, a natural filter. The average concentration of the five bottled water brands was 4.2 ppb, or 233 times higher than the human health surface water standard.
The observed values were not unexpected. Seattle's water supply is predominantly from surface waters. Bottled waters are predominantly from groundwaters. Arsenic is naturally present in minerals and "pristine" groundwaters will typically have higher mineral levels (including arsenic) than surface waters. This is especially true in the western states.
If you choose to believe EPA's derivation of the arsenic human health surface water quality standards is valid, then you need to know that bottled water imposes a far greater hypothetical health risk than for many other chemicals and routes of exposures that the media, environmental activists, regulators and politicians typically express outrage about and demand actions on.
However, none of the observed concentrations in the bottled water, or the tap water exceeded EPA's present drinking water maximum contaminant level of 50 ppb even though they exceed EPA's surface water quality standards.
The interesting thing about the different types of standards is how they are applied. Each is intended to protect human health. The more stringent numbers typically are applied to discharges of treated waste waters while drinking water supplies have only to comply with the less stringent numbers.
Another point to consider is that the combination of human health arsenic standards and naturally occurring arsenic levels creates a nonsensical regulatory program.
Arsenic concentrations in lakes, streams and rivers in Washington state typically are 0.1 to 1 ppb. Ocean water is about 1.7 ppb. Groundwater in Washington and other western states is typically higher. When background levels exceed a standard, as in the example of arsenic in Washington, then mixing zones are typically not allowed for dischargers and either the background concentration or the standard itself becomes an effluent limit, with no dilution benefit allowed.
The regulatory effect is such that because of human health concerns, you could not receive a permit to pour bottled water into Lake Washington, even though you can drink it. However, pouring it into surface waters is precisely what all consumers are doing, after filtering it through their bodies and through their community's waste water treatment plant.
There is no logical explanation for the differences between the drinking water standards and the surface water human health standards and their application. It is absurd to have water quality standards set more stringent than natural background levels. When this happens, mixing zones are of no benefit, forcing costly added treatment to produce little or no real change.
Very few states have standards for arsenic as low as ours. Twenty-two states set their arsenic human health surface water quality standard equal to the drinking water maximum contaminant level of 50 ppb. EPA readily approves these.
To help compare 50 ppb with our state's standards on a true scale, consider the following: If 50 ppb equals the top of the Columbia Center in downtown Seattle (943 feet) then 0.14 ppb is located 2 feet 8 inches above the pavement, and 0.018 ppb is located 4 inches above the pavement.
If the Environmental Protection Agency truly believes the standard it has imposed on Washington is valid, then it has an obligation to advise consumers of bottled water of the great risks they are taking. Wastewater treatment plants will have to treat their discharges to levels cleaner than natural spring water, at very substantial costs, which will be passed on to their ratepayers.
Perhaps sales of bottled water should be banned in the interest of human health or as one of many new source control measures to help wastewater treatment plants comply with the surface water quality standards?
Is all this necessary? Should people stop drinking bottled water?
I believe that is not necessary. Although it is difficult to understand the public's fascination with bottled water, the arsenic levels in the water are not dangerous and are below drinking water MCLs. The public should realize, however, that despite the high prices they pay, in most cases the bottled water producers have done little or nothing to add value to their raw material.
There are numerous technical issues that raise legitimate challenges to the validity of the arsenic human health surface water standards. The costs for complying with these standards will be enormous, and will result in imperceptible changes for the receiving waters.
In February, a petition for rulemaking on behalf of the cities of Everett and Tacoma was submitted to the Department of Ecology. In April, Ecology responded that it would go through a two-year rulemaking process to develop a state human health surface water arsenic standard and it would try to develop some implementation guidance in the interim.
Lincoln Loehr is an environmental analyst with the firm of Heller, Ehrman, White and McAuliffe in Seattle.