Perchlorate is a chemical most commonly used in rocket fuel, flares, and fireworks, but potential federal regulation of its presence in drinking water may bring utilities down to earth.
The naturally occurring and man-made contaminant is also used in fertilizers, and scientific research has indicated that, above certain concentrations, it may have adverse effects on hormone production and development if consumed. That threat has been on federal radar since initial investigation began around 1992.
In 2011, the U.S. EPA decided to regulate perchlorate under the Safe Drinking Water Act (SDWA). This reversed a preliminary determination made in 2008, after the agency considered some 38,000 public comments received in response to a 30-day supplemental request for input.
This was the first time the EPA had moved to regulate a substance from its Contaminant Candidate List, following the 1996 SDWA Amendment requiring it to make a regulatory decision for at least five contaminants on the list every five years.
Since that red-letter moment, water utilities across the country have been waiting for more details.
Preparing For The Unknown
For the last four years, the EPA has been considering perchlorate’s potential health risks and occurrence in drinking water as it develops information to support a national primary drinking water regulation (NPDWR). It will be difficult for water utilities to prepare for the cost of a forthcoming regulation until the EPA determines the details.
The agency’s draft physiologically-based pharmacokinetic (PBPK) model — a health-risk model for use in determining the maximum contaminant level (MCL) goal for perchlorate — is expected sometime this summer. Following the release of that draft for public comment, the EPA will initiate a peer review process in the fall. The Hill reports that the timeline for an ultimate ruling has been delayed until March 2017, though it’s possible a decision will be reached sooner.
Until then, water utilities are stuck in limbo.
“Utility impact is highly dependent on what MCL can be supported by the PBPK modeling in relation to the exposure reduction potential,” said Dr. Kevin Morley, security and preparedness program manager at the American Water Works Association (AWWA).
Concerned about perchlorate contamination, California and Massachusetts moved forward with implementing state MCLs well in advance of the EPA’s regulatory delays. Systems in California must adhere to a 6 µg/L standard for perchlorate, established in 2007, while Massachusetts systems comply with a 2 µg/L standard established in 2006.
Morley says these state regulations may inform the EPA’s decision, as they have identified a change in perchlorate occurrence since the agency’s Unregulated Contaminant Monitoring (UCM) data was compiled over 10 years ago. This data originally found that over 80 percent of perchlorate occurrence was at a concentration of less than 12 ppb, a figure that may be reduced based on the states’ more recent occurrence data.
“At minimum, we believe that any federal action must account for the California and Massachusetts compliance. It would not be appropriate for the EPA proposed rule to take credit for exposure reductions that have already been accrued as a result of state regulatory actions.”
The Cost Of Compliance
Whatever the details of the regulation, it will impose significant compliance costs on a subset of utilities.
A 2013 perchlorate treatment cost assessment conducted by AWWA found that “national compliance costs for a perchlorate MCL ranging from 2 to 24 µg/L is smaller than estimated compliance costs for other drinking water regulations.” The assessment notes that the $120 million annual cost for adhering to a 4 µg/L perchlorate MCL would be markedly less than the $320 million it costs for water utilities to adhere to the Arsenic Rule.
However, AWWA found that the cost to some small water systems could prove significant. As less than 3 percent of public water systems (800 or fewer, per AWWA estimates) are likely to be affected by a potential perchlorate MCL, the cost to those individual systems serving a population of less than 500 will be roughly $3 per 1,000 gallons.
“Part of the challenge is that while the national cost is relatively low, the total burden will be carried by a very small universe of utilities, many of which are small systems,” said Morley. “There is an economic scale issue by which the unit cost for a small system is quite significant.”
AWWA has observed that some systems will abandon high concentration water sources to avoid these treatment burdens. Of course, this results in source water replacement costs.
Systems that use sodium hypochlorite should also be aware of potential compliance issues, as over time and under certain conditions, the chemical degrades into perchlorate. AWWA developed an estimation tool for its members to mitigate potential compliance issues stemming from hypochlorite use.
More information about perchlorate removal methods and equipment can be found on Water Online’s Drinking Water Contaminant Removal Solutions Center.
An Unclear Future
Just as it’s difficult to determine next steps for compliance without a detailed ruling, the ultimate benefit of federal action won’t become clear until more information is released. Much still hinges on the pending EPA definition of what constitutes “adverse impact.”
If the PBPK modeling results determine that only a high level of perchlorate concentration could have significant effect on public health, then a subsequent ruling would be lenient and uncostly for utilities. If the EPA finds that perchlorate needs to be strictly regulated, it will make a world of difference for the systems that must adhere.
For now, the industry remains on standby.
Image credit: "Firework cake," © 2013 Simon Talbot-Hurn, used under an Attribution 2.0 Generic license: http://creativecommons.org/licenses/by/2.0/