CU letter to the EPA regarding arsenic in rice

September 20, 2012
Lisa P. Jackson
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue N.W. Washington, DC 20004
Dear Administrator Jackson:
Consumers Union, the public policy and advocacy arm of Consumer Reports¸ writes regarding exposure to arsenic from food sources, particularly rice. As you know, one of the ways that arsenic gets into the food supply is through the use of arsenical pesticides in food production. Consumer Reports has published in its November 2012 issue a study on arsenic levels in rice and rice-based products, which found arsenic in all the more than 60 products tested. All products raised some level of concern regarding cancer risks. We are therefore concerned with organic arsenical pesticides, the ongoing toxicological risk assessments of various forms of arsenic and the use of sewage sludge as a fertilizer in crop production.
Organic Arsenical Pesticides
We commend the U.S. Environmental Protection Agency (EPA) for voluntary cancellations for most uses of the organic arsenical pesticides (monosodium methanearsonate [MSMA], disodium methanearsonate [DSMA], calcium acid methanearsonate [CAMA], and cacodylic acid and its sodium salt).1 Given our findings, however, we urge the EPA to cancel all remaining uses of MSMA, including use on cotton, golf courses, sod farms and rights-of-way.
In addition, the agency has stated that it would conduct a scientific peer review and “convene a joint review by the EPA Science Advisory Board (SAB) and FIFRA Science Advisory Panel (SAP) in the first half of 2012” to review the science behind the cancellation of these uses of MSMA, with the exception of cotton uses. We understand, though, that EPA has not convened such a meeting. We urge the agency not to delay the cancellation of these uses of MSMA from the target date of December 31, 2012. We also urge EPA not to permit any use of existing stocks of MSMA after December 2013.
We also understand that EPA continues to allow MSMA to be used on cotton for control of weed pests, particularly Palmer amaranth (Amaranthus palmeri), a serious weed pest of cotton that is resistant to glyphosate and that can lead to a 25% or more loss of revenue in infested cotton fields.2 The agency estimates “that the drinking water risk from the remaining use on cotton to be between 1 x 10-4 and 4 x 10-4 . . . applications of MSMA to cotton will result in residues of inorganic arsenic in water at levels of approximately 4 ppb, less than the established MCL [maximum contaminant levels]of 10 ppb.” We note that this MCL is not a health-based standard, but is instead, a standard based in large part on economic feasibility. However, given concerns about the toxicological risk assessments from chronic exposure to arsenic, we urge the agency to minimize the level of arsenic in the environment to the largest extent possible and cancel the use of MSMA as an herbicide to control A. palmeri.
Reports on Health Risks Associated with Inorganic Arsenic
We respectfully request that EPA finalize the 2010 Draft Integrated Risk Information (IRIS) Report on the carcinogenicity risk of inorganic arsenic (iAs). In addition, we urge the agency to develop a report on the non-carcinogenicity risk of iAs.
In early 2010, EPA released the draft IRIS Toxicological Review for Inorganic Arsenic (cancer) to their Science Advisory Board (SAB) and to the public for review and comment. We urge EPA to finalize this draft IRIS Toxicological Review for Inorganic Arsenic (cancer). In addition, we urge EPA to complete their IRIS Toxicological Review for the cancer risk of organic arsenic, e.g. dimethylarsinic acid (DMAv). We also urge EPA to produce a Draft IRIS health assessment for the non-cancer risk of iAs, as the agency has previously indicated.
Sewage Sludge
We also respectfully request that you greatly reduce the limit for arsenic allowed in sewage sludge fertilizers used in crop production or in home gardens.
In 1993, EPA adopted “Standards for the Use and Disposal of Sewage Sludge,”3 which set standards for the allowable arsenic levels in sewage sludge applied to land for fertilizer use. For sewage sludge intended to be used in crop production or on home gardens (e.g. Class A and EQ sludge), the maximum allowable concentration for arsenic is 41 mg/kg or 41,000 ppb, with a cumulative loading rate of 41 kg/ha.4 However, new science on arsenic developed since 1993 strongly suggests that potential carcinogenicity is much larger than originally considered. We therefore urge the agency to significantly reduce the maximum allowable concentration of arsenic in sewage sludge intended to be used in crop production or on home gardens (e.g. Class A and EQ sludge). As a first step, EPA could reduce the permitted level in Class A and EQ sludge to 10 mg/kg, with a cumulative loading of 10 kg/ha (as Maine already requires5). In the longer term, we believe that EPA should revise its risk assessment and come up with new values for the arsenic permitted in Class A and EQ sludge.
Thank you for your consideration of our concerns. A copy of our article is attached.
Michael Hansen, Ph.D.
Senior Scientist
Urvashi Rangan, Ph.D.
Director, Consumer Safety and
(2) Culpper AS, Witaker JR, MacRae AW and AC York. 2008. Distribution of glyphosate-resistant Palmer Amaranth (Amaranthus palmeri) in Georgia and North Carolina. Journal of Cotton Science, 12: 306-310. At:
(3) 40 CFR Part 503.
(4) Harrison, EZ. 1997. A Brief Summary of the Federal Standards for Land Application of Sewage Sludge. Cornell Waste Management Institute. At: