|Perchlorate Analysis in Drinking Water|
California is one of only a few states to currently regulate perchlorate in drinking water and in 2011 proposed a new public health goal (PHG) of 1 ug/L. The current CA MCL is 6 ug/L, EPA has indicated that they will propose an MCL for perchlorate in early 2013, but there is as yet no indication of what that proposed MCL will be, although EPA has stated that they are concerned with exposure of infants and other sensitive sub-populations, so the proposed MCL could be relatively low.
Eaton Analytical has been testing perchlorate at levels below the proposed CA PHG of 1 ug/L in drinking water and drinking water sources for more than 10 years by both EPA Method 314 and EPA method 331. The State of California currently has a Detection Limit of Reporting (DLR) of 4 ug/L. However the State of Massachusetts set a Maximum Contaminant Level (MCL) of 2 ug/L in 2007, so labs reporting data to Massachusetts need to achieve a reporting limit of 1 ug/L (MDL of <0.5 ug/L). Eaton Analytical is one of only four labs certified in Massachusetts for perchlorate analysis.
Eaton Analytical reports certified perchlorate data to an MRL of 0.5 ug/L or less using both method 314 (which is limited by total dissolved solids levels and subject to potential matrix interferences, leading to false positives or false negatives) and method 331 (LC-MS-MS) and has been certified continuously in Massachusetts for low level perchlorate since certification was first offered. Eaton Analytical is the only California based laboratory to be approved in Massachusetts for low level perchlorate monitoring, having demonstrated the ability to meet the required reporting level.
In 2010, Eaton Analytical analyzed more than 500 samples for perchlorate by method 331 and more than 4,000 samples at a 0.5 ug/L reporting level by method 314. Since then we have analyzed numerous additional samples by 331, as clients rely on the reliability of that method.
When Massachusetts first proposed an MCL for perchlorate, Eaton Analytical Labs conducted an AWWA funded study of lab capability to meet the target reporting limit of 0.5 ug/L and demonstrated that not all Massachusetts certified labs could consistently provide reliable data at the proposed reporting limit. Results of this study were presented at several national conferences as long ago as 2005.
Until January 7, 2011 California had a public health goal (PHG) of 6 ug/L, and an MCL of 6 ug/L. However on January 7 of that year, the California Office of Environmental Health Hazard Assessment (OEHHA) revised the proposed PHG to 1 ug/L. While we have demonstrated that it is possible to analyze perchlorate at concentrations below the proposed PHG, particularly using method 331, care is required to ensure accurate results. Because perchlorate is considered an acute pollutant, California requires that any detects over the MCL be reported to the utility within 24 hours of analysis completion and there are multiple cases in California where wells were shut down either temporarily or permanently as a result of perchlorate occurrence.
EPA and Other State Actions
EPA has been evaluating the desirability of setting an MCL for perchlorate for several years. In 2011, EPA announced that they would propose a regulation for perchlorate in 2013. In the interim several states already have MCLs for perchlorate. The lowest current MCL is in Massachusetts, which has had an MCL of 2 ug/L since 2007. Additionally the International Bottled Water Association (IBWA) has a perchlorate standard of 2 ug/L in their Model Code, even though FDA has not yet promulgated a standard for perchlorate.
Generally samples for perchlorate are analyzed directly without pretreatment. However EPA method 331, which is the low level LC-MS-MS method requires field filtration through a sterile filter to eliminate the possibility of bacterial removal of perchlorate. The state of Massachusetts requires this preparation for all samples, regardless of method. In late 2010 the state of Nevada adopted the same guidance. Massachusetts also requires the sterile filtration even for bottled water source samples. California has issued guidance eliminating the need for filtration regardless of method as long as samples are collected in bottles with sufficient headspace to ensure that they remain aerobic. For best results, unless you know the data will only be used for California compliance, it is recommended that all samples be field filtered, even though this guidance has not been adopted by any other regulatory agencies as yet. Once EPA proposes and promulgates an MCL they will indicate whether field filtration is required for compliance samples.
Reporting Level vs California Public Health Goal
The proposed public health goal is 1 ug/L as of January 7, 2011. However the State of California established a reporting limit of 4 ug/L when a 6 ug/L MCL was established; therefore most of the data in the California state database shows a 4 ug/L reporting limit, regardless of whether the lab was able to report to a lower level and thus its usability may be limited. This reporting limit was established when the initial PHG of 6 ug/L was promulgated and has not yet been revised downward. As noted earlier, EPA method 314 can be modified slightly to achieve a reporting level of 0.5 ug/L, provided the total dissolved solids level is not too high. EPA method 331, which Eaton Analytical recommends, can achieve a reporting level of 0.05 ug/L if required by utilities, even in high TDS samples.
The most common treatment techniques for perchlorate are either ion exchange or biological reduction. RO is also an effective treatment. There is little, if any, data available to demonstrate the effectiveness of these treatment technologies to meet the proposed PHG.
In the press release accompanying the revised proposed PHG, OEHHA indicated that exposure to perchlorate can affect infant brain development, growth, and other key body functions. Perchlorate is known to damage the thyroids ability to take in and process iodide, which is a nutrient essential to brain development, growth, heart function, and other systems.
Studies conducted by OEHHA scientists and others revealed that perchlorate harms the health of babies at lower levels than healthy adults. At the same time, a recent study of Boston-area new mothers indicates that nearly half of all infants may not receive enough iodide from their mothers' milk.
OEHHA's draft PHG also incorporates new data on how much water infants consume per pound of body weight. It also considers infants' intake of perchlorate from infant formula.
EPA is still evaluating data on perchlorate to determine a recommended safe level, but some of EPA's data and reports suggest levels as low as 2 ug/L are a possiblity.
Eaton Analytical has been conducting analysis at low levels using method 314 and 331 for more than 10 years and can assist clients in assessing exposure at levels below the new proposed California PHG. For further information, or to arrange for testing, please contact your project manager.