Perchlorate Mystery Surfaces in Texas

30,000 square miles in western Texas 

KRIS CHRISTEN / Environmental Science and Technology 2oct03

[More below and also see Perchlorate Found in Texas Milk]

Researchers from Texas Tech University (TTU) have uncovered the largest area of contiguous perchlorate contamination in the United States, which exceeds 30,000 square miles in western Texas. Although concentrations are at low levels—the bulk of them in the 4 parts-per-billion (ppb) detection range—the big question now is, Where is the perchlorate coming from?

It all started when the Texas Commission on Environmental Quality (TCEQ) was conducting routine sampling under the U.S. EPA’s Unregulated Contaminant Monitoring Rule, according to Steve Walden, a TCEQ special projects manager. After detecting trace levels of perchlorate in drinking water wells supplying the Midland, Texas, area and in an elevated water storage tank in the city of Levelland, roughly 100 miles north of Midland, TCEQ continued taking samples. Surprisingly, the agency found perchlorate almost everywhere it looked.

TCEQ turned to TTU for help, and the study area was expanded to nine counties around the sites where perchlorate was found in an attempt to establish a contamination perimeter. Of the 217 public drinking wells the TTU researchers tested, 73% had detectable perchlorate concentrations of more than 0.5 ppb and 35% had concentrations equal to or above 4 ppb. California’s draft drinking water standard is currently set in a range of 2–6 ppb. The highest level found was 58.8 ppb, according to Andrew Jackson, an environmental engineer at TTU, who presented the findings in late July at a perchlorate symposium in Sacramento, Calif.

Finding no limit to the contamination, the TTU researchers expanded their study to 54 counties, an area of roughly 60,000 square miles, which is bigger than some states. “In the northern part of the Panhandle [in northern Texas], we’re finding much reduced occurrence, but in the bottom two-thirds, it’s fairly consistent,” Jackson says.

The findings could have huge implications for the state, depending on whether EPA chooses to regulate perchlorate in drinking water in the low-parts-per-billion range. EPA recommended a preliminary drinking water limit of 1 ppb in 2002 (Environ. Sci. Technol. 2002, 36, 125A), but the risk assessment on which this draft limit is based is currently under review by the National Academy of Sciences (Environ. Sci. Technol. 2003, 37, 166A–167A).

Drinking water in western Texas is typically culled from a mix of surface and groundwater sources, the latter coming from the High Plains aquifer system. Here, the underground Ogallala aquifer is the main water source, and it is where most of the perchlorate was detected. “It’s a massive water resource for the state,” Walden says, adding that regardless of EPA’s decision, people will have to continue using these water supplies because no other options exist.

Until now, most perchlorate contamination has been associated with point sources. “They usually have a tight, controlled plume produced off some industrial site that used to manufacture or handle perchlorate,” Jackson says. An occurrence survey of national drinking water supplies published in 2002 by the American Water Works Association’s Research Foundation confirms this.

In Texas, however, no plume-like pattern is discernible, according to Jackson. Moreover, perchlorate’s occurrence is random. For example, the TTU researchers have found some wells yielding relatively high perchlorate concentrations immediately adjacent to wells with little or no detectable perchlorate.

The four scenarios considered to be most plausible for generating the widespread contamination are agricultural use of fertilizers containing perchlorate, in situ generation of perchlorate by an electrochemical reaction, a natural source, or some combination of these three. For example, TTU researchers believe that the high perchlorate concentrations initially detected in Levelland’s water storage tank were generated by the unit’s cathodic protection system through mechanisms confirmed in laboratory experiments. “A lot of oil wells, pipelines, and water wells have active systems on them,” Jackson says, but the parameters necessary for perchlorate formation have only been observed with this one tank.

More likely, the patchy occurrence points to a natural mineral source, either in the subsurface water where it’s dissolved and then transported to the aquifer, in the saturated zone, or possibly even an upwelling from deeper layers, Jackson says.

Researchers have found perchlorate in the low-parts-per-billion range in some naturally occurring evaporite materials in scattered locations in the Western hemisphere, says Greta Orris, a research geologist with the U.S. Geological Survey. It’s possible that the perchlorate in Texas could be coming from such a source, “but we don’t know enough yet at this point,” she notes. Also, she says, “Because the perchlorate is frequently present in such small amounts, it’s hard to isolate enough of it to study [the source] directly and try to figure out if it’s natural or manmade.”

Orris and Jackson predict, however, that the extent of low-level perchlorate occurrence, especially in Western aquifers and likely beyond Texas, has been underestimated and is more widespread than previously thought. “Nobody was looking for it before,” Jackson says, but now that detection limits are at the sub-parts-per-billion range, “more people are going to find it.”

source: http://pubs.acs.org/subscribe/journals/esthag-w/2003/apr/policy/rr_perchlorate.html 4oct03

Perchlorate Remediation Resources

The number of validated technologies for removing perchlorate from contaminated drinking water, groundwater, and soil is growing, even though U.S. regulation of the contaminant is stalled. The U.S. EPA’s Technology Innovation Office, the U.S. Department of Defense, and Calgon Carbon Corp. (which is one of the companies promoting a treatment modality) maintain websites with links to information about more than 60 technologies. To date, the majority of the technologies involve bioremediation (Environ. Sci. Technol. 1999, 33, 515A). For more information, go to http://cluin.org/perchlorate, www.denix.osd.mil/denix/Public/Library/Water/Perchlorate/perchlorate.html, or www.perchlorateinfo.com.

source: http://pubs.acs.org/subscribe/journals/esthag-a/37/i19/pdf/1003news7.pdf#2 3oct03

EPA Perchlorate Decision Takes Many by Surprise

Environmental Science & Technology 21aug03

The U.S. EPA announced in July that it would not move forward with developing regulations for any unregulated drinking water contaminants at this time. This decision surprised many in the drinking water arena, particularly because perchlorate, which is the primary ingredient used in manufacturing solid propellant for rockets, missiles, and fireworks, is a high-priority contaminant of concern on EPA’s Contaminant Candidate List (CCL). The list includes 50 chemical and 10 microbial contaminants, and EPA is required under the Safe Drinking Water Act to select at least 5 contaminants from this list every 5 years and determine whether a regulation would likely result in a reduction of health risks.

EPA recommended a preliminary drinking water limit of 1 part per billion (ppb) for perchlorate in 2002 (Environ. Sci. Technol. 2002, 36, 125A), but there are still many unknowns, says John Millett, an EPA spokesperson. He points to ongoing activities such as data collection on occurrence, work to improve low-level detection methods, and reviews of perchlorate removal technologies, all of which will need to be finalized before a standard can be developed. Additionally, the National Academy of Sciences is currently reviewing the risk assessment on which the draft 1-ppb limit is based (Environ. Sci. Technol. 2003, 37, 166A–167A).

Environmentalists are concerned, however, that “the effect of EPA’s latest decision will be to kick perchlorate and everything else into the next five-year cycle, which means it’s very unlikely that they’re going to get around to regulating these things for about a decade,” says Erik Olson, a senior attorney with the environmental group Natural Resources Defense Council. “If EPA can’t decide that a regulation is needed for a chemical like perchlorate, which is contaminating the drinking water of 20 million people and is at levels above what EPA’s risk assessment says are safe, I think it’s a stunning admission that the agency’s process has broken down.”

Indeed, EPA has confirmed perchlorate releases in groundwater and surface waters in at least 20 states. Contamination is particularly extensive in California, and the state is moving forward with a drinking water standard “because we have a problem here, and we need to deal with it,” says Robert Miller, a spokesperson for the state’s Department of Health Services (DHS). California’s legislature set a deadline of January 2004 for the standard, but a lawsuit by two aerospace corporations has slowed the process. DHS officials hope to establish a public health goal by this fall and a standard soon afterwards. David Spath, chief of DHS’ Division of Drinking Water and Environmental Management, said at a perchlorate symposium in Sacramento in late July that the state would likely adopt a standard by emergency regulation in order to meet the January deadline. The state’s draft goal is currently set in a range of 2–6 ppb.

In EPA’s defense, Millett says that the agency is not precluded from taking actions on CCL contaminants before the end of the next regulatory determination cycle, which is August 2006, if information becomes available beforehand. In fact, he notes that “EPA feels fairly confident that we will be able to make a sound regulatory determination one way or the other on perchlorate by this time next year.”

State drinking water officials and utilities say that they’ll be closely tracking EPA’s progress on this front and want to see EPA complete its studies before a standard is set. “Perchlorate, in particular, is one we have to make sure we get right,” says Jim Taft, executive director of the Association of State Drinking Water Administrators and former chief of the targeting and analysis branch of EPA’s Office of Ground Water and Drinking Water. “It’s important that there be good, strong scientific information upon which there’s a fair amount of consensus.” Currently, Taft notes, there are still questions about the severity of the health effects of this contaminant at various concentrations in drinking water.

Meanwhile, EPA did finalize decisions for nine of the CCL contaminants, determining that no regulatory action is “appropriate or necessary” at this time. The agency expects to publish an updated CCL in late fall, according to Millett. For more information, go to www.epa.gov/safewater/ccl/cclregdetermine.html. —KRIS CHRISTEN

source: http://pubs.acs.org/subscribe/journals/esthag-w/2003/aug/policy/kc_epadecision.html 3oct03

Perchlorate Regulation Faces Further Delay

Environmental Science & Technology 24apr03

A controversial U.S. toxicological review of perchlorate has taken an unexpected twist: The final review, which was due out early this year, is being delayed because the EPA, the Department of Defense (DoD), and several other U.S. agencies have decided that the National Academy of Sciences (NAS) should now review the issue.

EPA’s January 2002 draft toxicological report recommended a drinking water limit of about 1 part per billion (ppb). DoD, however, thinks that this analysis is flawed for many reasons, but particularly because EPA relies primarily on lab animal data, according to an Air Force spokesperson. DoD wants to place more emphasis on human data.

The decision to ask for the review was based on interagency talks between officials from EPA, DoD, NASA, the White House’s Council on Environmental Quality, and the Office of Management and Budget that have been going on for some time, according to William Farland, EPA’s Office of Research and Development acting deputy administrative director for science. The NAS review is likely to take about two years and will delay any regulatory action on perchlorate.

Perchlorate can reduce thyroid hormones by inhibiting iodine uptake. Because thyroid hormones play an important role in brain development, EPA used a battery of neurodevelopmental tests with rats to estimate the risks of perchlorate exposure. The laboratory experiments used in the perchlorate review are part of EPA’s approved battery of neurodevelopmental tests and include measurements of brain size and shape, animal behavioral, and thyroid hormone levels. But the report of the external peer review committee that evaluated the current draft toxicological review indicates that some of the reviewers were concerned about the quality of the experimental studies.

Some reviewers noted that the work on rat thyroid hormone levels did not detect consistent effects either within, or across, several studies. The experts believe that this happened because the labs chose an analytical setup that was not sufficiently sensitive to reliably measure low levels of thyroid hormones in the rats.

In addition, most of the reviewers agreed that the measurements to characterize brain dimensions were subject to serious artifacts. This is because small changes in the orientation of the brain slices used to determine size dramatically affect the measurements, according to neurotoxicologist Michael Aschner at Wake Forest University School of Medicine, in Wake Forest, N.C., who led this aspect of the peer review. “There is no dose–response relationship, no consistency, there’s just a zig-zag.” In addition, two studies done in 1998 and 2001 “are not reproducible; there’s absolutely no consistency between the two, ” says Aschner.

But EPA toxicologist Kevin Crofton argues that the overall data are convincing. “There is variability between studies, and some of this reflects the difference between labs and the difficulty of the studies. But everybody who has ever looked at thyroid hormones sees these effects, so they must be real,” he says.

In addition to concerns about the crucial animal studies, some of the reviewers recommended that EPA give more consideration to studies with human volunteers. This is also what the military wants, according to the Air Force’s written comments on the toxicological review.

EPA had asked NAS two years ago to consider the acceptability of human volunteer studies conducted by nongovernmental organizations. The agency’s interim policy is to refuse to accept such studies until it receives NAS recommendations and revises its policy. However, the NAS committee examining the issue was still holding hearings on March 19.

Studies already conducted involving healthy human adult volunteers suggest that it takes much higher doses of perchlorate to harm humans, according to the scientists who did the studies. Oregon Health and Science University professor Monte Greer and colleagues estimated that 5.2-6.4 micrograms per kilogram per day would have no effect on iodine uptake. This is approximately the adult dose from drinking water containing perchlorate at 180 or 220 ppb, well above the draft standard.

The conflict between the animal and human studies is a red herring, according to Grant Anderson, who studies thyroid hormones and brain development at the University of Minnesota Department of Medicine in Minneapolis. This is because adults are not the most vulnerable population. In humans it is widely acknowledged that thyroid hormones exert their greatest effect on brain development when the developing child is making its own thyroid hormones—late in pregnancy and after a baby is born, he says. This means that the effects of perchlorate on an adult’s iodine uptake or thyroid hormone status are not the most relevant data for assessing how perchlorate exposure affects the developing brain. —REBECCA RENNER

source: http://pubs.acs.org/subscribe/journals/esthag-w/2003/apr/policy/rr_perchlorate.html 3oct03

Perchlorate Drinking Water Recommendation Drops

Environmental Science & Technology 25jan03

 A long-awaited U.S. EPA draft toxicological report issued on January 18 finds that perchlorate is likely to be more harmful to human health than previously thought. In response to the report’s conclusion that perchlorate concentrations of less than 1 part per billion (ppb) are safe for human consumption in drinking water, the California Department of Health reduced its advisory action level from 18 ppb to 4 ppb. The state, which is currently in the process of setting its own drinking water standard, is one of the southwestern states most affected by perchlorate-contaminated groundwater.

Perchlorate salts, which are used in solid rocket fuel, fireworks, and auto air bags, have been found in ground and surface water throughout the United States. Perchlorate can cause adverse effects by blocking the uptake of iodine by the thyroid, and scientists have been struggling for more than a decade to determine whether exposure to minute amounts of the compound in drinking water can have a long-term detrimental effect on human health. Since 1992, EPA has recommended safe levels ranging from 4 to 18 ppb.

The recommendation is being greeted with a mixture of surprise, caution, and approval by scientists involved with the issue. “I’m surprised; this is completely impractical because it’s lower than the current detection limit,” said one academic scientist, voicing a common reaction. The detection limit for ion chromatography, the best commonly available analytical method, is 4 ppb. “If this recommendation is right, we should be seeing effects in the general population. But widespread adverse effects do not occur,” said a chemist, referring to the report’s finding that low-level exposure to perchlorate causes neurobehavioral effects during development.

The new draft report is a revision of a 1998 draft review prepared by EPA’s National Center for Environmental Assessment that supported a 32-ppb standard concentration (Environ. Sci. Technol. 1999, 33, 110A). The neurodevelopmental effects that were first noted in the 1998 review form the basis for the new draft reference dose. In particular, brains of rat pups whose mothers drank perchlorate-laced water were found to be different in size and shape from control rats even at the lowest dose, 0.01 mg/kg-day. This lowest observed adverse effect level is 10 times lower than the level reported in the 1998 review. The newer report also incorporates a higher safety factor of 300, which is 3 times the safety factor used in the 1998 review. These two factors drive down the new reference dose to 0.00003 mg/kg-day.

But other scientists applaud the new review, “This is state-of-the-science toxicology,” said Kevin Mayer, the coordinator for perchlorate issues for the U.S. EPA Region 9, which includes California.“For those of us in the field dealing with this problem, it gives us a greater level of confidence in the recommendations, knowing the level of effort and sophistication embodied in this work,” Mayer says.

“This is a big step forward by the EPA, confirming the latest scientific research that shows perchlorate is toxic even at very low doses,” says Environmental Working Group analyst Renee Sharp. In a report issued last year, the environmental group criticized EPA’s previous draft recommendations.

EPA officials say that once the report is finalized, it will be a major factor in the possible development of federal regulatory standards, a process likely to take several years. The first step is external peer review and public comment. A public peer review workshop on the draft assessment has been scheduled for March 5-6 in Sacramento, and the final assessment is expected in late summer. —REBECCA RENNER

source: http://pubs.acs.org/subscribe/journals/esthag-w/2002/jan/policy/rr_perchlorate.html 3oct03