[CPEO-MEF] Wide-spread, low concentration perchlorate

[Lenny Siegel <lsiegel@cpeo.org>]

"Evaluation of Alternative Causes of Wide-Spread, Low Concentration
Perchlorate Impacts to Groundwater," prepared by GeoSyntec Consultants
for the Strategic Environmental Research and Development Program (SERDP)
and officially dated May 5, 2005, is available on line  at a 54-page,
424 K PDF file at 
http://www.serdp.org/research/cp/cp-1429.pdf

Here is the EXECUTIVE SUMMARY

The frequency of detection of perchlorate in groundwater and drinking
water supplies has been steadily increasing since its initial
identification as a chemical of concern in 1997. It is currently
estimated that perchlorate is present in groundwater in at least 30
states and affects the drinking water supplies of more than 20 million
people in the southwestern United States (U.S.). The source of
perchlorate in water supplies has typically been attributed to U.S.
Department of Defense (DOD), National Aeronautics & Space Administration
(NASA) and/or defense contractor facilities that have used ammonium
perchlorate (AP) in rocket and missile propellants. Perchlorate impacts
to groundwater and surface waters in southern Nevada and southern
California have also been attributed to the historic production and
release of perchlorate from a former chemical manufacturing facility in
the Las Vegas, Nevada area (Hogue, 2003), which has impacted the surface
waters of Lake Mead and the Colorado River.

As a result of its high profile and its addition to the Unregulated
Contaminant Monitoring Rule (UCMR List 1), which requires perchlorate
analysis by large public water suppliers and selected small water
utilities, most public water supplies are now being routinely analyzed
for perchlorate. Through monitoring activities, perchlorate has been
detected at low levels (typically less than 50 µg/L) in a significant
number of areas without apparent military sources. Investigation
activities have linked these perchlorate impacts to various non-military
sources, including use of perchlorate-containing blasting agents for
quarrying and construction, manufacture of road flares, manufacture and
use of fireworks and pyrotechnics, use of perchloric acid in industrial
manufacturing, and use of Chilean nitrate fertilizers.

Perchlorate is known to be present in a significant number of products
and processes. Unfortunately, it has proven exceedingly difficult to
obtain records of perchlorate handling related to production and use of
many of these products and processes. As such, this review focuses on
five major perchlorate-containing products for which significant
quantity and use information is available: Chilean nitrate fertilizers;
fireworks; safety flares; blasting explosives; and
electrochemically-prepared (ECP) chlorine products. The key findings of
this review for each of these major perchlorate-containing products can
be summarized as follows:

Chilean Nitrate Fertilizer: Between 1909 and 1929 (the period for which
detailed information could be obtained), the U.S. imported an estimated
19 million tons of Chilean nitrate (Goldenwieser,1919; Howard, 1931), of
which an average of 65% was used as fertilizer (Brand, 1930). Assuming
an average perchlorate content of about 0.2% in Chilean nitrate (based
on U.S. Environmental Protection Agency research results), approximately
49 million pounds of perchlorate may have been unknowingly applied to
agricultural soils during this time period, for fertilization of crops
such as cotton, tobacco, fruits and vegetables. While the use of Chilean
nitrate fertilizers has steadily declined since about the 1930s, there
is evidence of continued use through the present day. Additional
evaluation of soils and groundwater in agricultural areas that have used
(and may still be using) Chilean nitrate fertilizers seems warranted to
evaluate whether past and/or present fertilizer practices can be
expected to be the cause of long-term, low concentration perchlorate
impacts to groundwater in some agricultural areas and watersheds.

Fireworks: In 2003, 221 million pounds of fireworks were consumed in the
U.S., with an estimated 3% produced domestically and the remainder
imported from China (APA, 2004a). Although perchlorate is widely used as
an oxidizer in firework formulations, there is little information
related to the amount of perchlorate residue remaining after burning of
fireworks and/or statistics on dud rates and blind stars that occur
during fireworks displays. As such, it is difficult to estimate
potential perchlorate inputs from fireworks to the environment. Recent
studies have detected perchlorate in soils, groundwater and/or surface
water following fireworks displays, and therefore, the potential
environmental impact of perchlorate from fireworks displays warrants
further scientific study.

Safety Flares: Preliminary research by Silva (2003a, 2003b) of the Santa
Clara Valley Water District in California indicates that 3.6 grams of
perchlorate can potentially leach from an unburned, damaged (i.e., run
over by a motor vehicle) 20-minute road flare. While numbers are not
available for total domestic flare production, assuming an average cost
per flare of $0.50 to $1.00 per flare and annual sales of $20 million by
the largest domestic manufacturer, some 20 to 40 million flares may be
sold annually. Given this estimate, up to 237,600 pounds of perchlorate
could leach from road flares annually. Surface runoff from highways and
roads represents a potentially significant and largely uninvestigated
impact to surface water and groundwater quality. Additional evaluation
of the potential for perchlorate impacts to surface waters and
groundwater from safety flare use appears warranted.

Blasting Explosives: Some water gels, emulsions, and non-electric
detonators can contain substantial amounts of perchlorate (e.g., up to
30% by weight). While, most of the perchlorate in the explosives is
expected to be consumed in the detonation, poor housekeeping practices
(i.e., spillage), improper use, or misfires can potentially result in
perchlorate contamination of surface and ground waters, as has been
reported for multiple sites in Massachusetts. Given that the U.S
produces approximately 2.5 million tons of explosives annually,
perchlorate could potentially be released into the environment
nationwide in substantial amounts. Currently, no publicly-available data
exist to quantify potential perchlorate impacts from blasting. More
studies are required to assess and quantify the potential impact of
blasting explosives on perchlorate contamination of surface and ground waters.

ECP Chlorine Chemicals: During the electrochemical manufacture of
chlorine products, such as chlorate, from chloride brine feedstocks,
perchlorate may be formed as an impurity at concentrations of 50 to 500
mg/kg. The estimated North American annual chlorate manufacturing
capacity is 2.4 million tons, whereas the total annual consumption of
sodium chlorate in the U.S. is approximately 1.2 million tons. The pulp
and paper industry uses approximately 94% of all sodium chlorate
consumed in the U.S. for on-site production of chlorine dioxide to
bleach cellulose fibers. Effluents from pulp mills have been reported to
contain chlorate (1 to 70 mg/L) but there is little information
available as to the potential for perchlorate release from these
facilities. Sodium chlorate is also used as a non-selective contact
herbicide and a defoliant for cotton, sunflowers, sundangrass,
safflower, rice, and chili peppers. The use of sodium chlorate in the
pulp and paper industry and as a defoliant has the potential to
contribute perchlorate to the environment and needs to be better understood.

The United States DoD, NASA and related defense contractors are likely
to be the most significant domestic users of perchlorate, and as such, a
significant percentage of identified groundwater perchlorate impacts are
likely to be attributable to DoD, NASA, and related defense contractor
facilities. However, cases exist, and many more are likely to surface,
where perchlorate impacts result from combinations of military,
non-military, and/or natural inputs. The ability of DoD, NASA, and
defense contractors to accurately apportion the relative contributions
from these varying sources, and hence to properly determine liability
and control cleanup cost, lies in having a good understanding of the
wide variety of products and processes that may contribute perchlorate
to the environment and through the development and validation of
appropriate forensic tools. This review is intended to assist DOD, NASA,
and defense contractors in identifying the significant number of
industrial and commercial processes and products that contain
perchlorate and to estimate the potential contribution of perchlorate to
the environment (past and/or present) from non-military products or
processes. 

-- 


Lenny Siegel
Director, Center for Public Environmental Oversight
c/o PSC, 278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918
<lsiegel@cpeo.org>
http://www.cpeo.org
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