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Table of Contents 

Contents

I. Introduction ............................................................................................................................. 3

II. Scientific Assessments ............................................................................................................ 5

A. Human Health Assessment .................................................................................................... 5

Hazard Characterization .......................................................................................................... 5

Dietary Exposure Assessment................................................................................................. 5

Residential and Occupational Exposure ................................................................................. 5

Aggregate Risks ...................................................................................................................... 5

Human Incidents ..................................................................................................................... 5

Food Tolerances ...................................................................................................................... 6

B. Environmental Assessment ................................................................................................... 6

Ecological Risk Characterization ............................................................................................ 6

Endangered Species Assessment ............................................................................................ 7

Endocrine Disruptor Screening Program ................................................................................ 7

III. Interim Registration Review Decision ................................................................................. 8

IV. Next Steps and Timeline ...................................................................................................... 8
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I. Introduction 

This document is the Environmental Protection Agency’s (EPA or the Agency) Interim 

Registration Review Decision for iron salts and is being issued pursuant to 40 CFR sections 

155.56 and 155.58. A registration review decision is the Agency's determination whether a 

pesticide meets, or does not meet, the standard for registration in the Federal Insecticide, 

Fungicide, and Rodenticide Act (FIFRA). The Agency may issue, when it determines it to be 

appropriate, an interim registration review decision before completing a registration review. 

Among other things, the interim registration review decision may require new risk mitigation 

measures or impose interim risk mitigation measures. Additional supporting documents can be 

found in EPA’s public docket for the registration review of iron salts (docket number EPA-HQOPP-2008-0626) at www.regulations.gov. 

FIFRA, as amended by the Food Quality Protection Act (FQPA) of 1996, mandates the 

continuous review of existing pesticides. All pesticides distributed or sold in the United States 

generally must be registered by the EPA based on scientific data showing that they will not cause 

unreasonable risks to human health or to the environment when used as directed on product 

labeling. The registration review program is intended to make sure that, as the ability to assess 

and reduce risk evolves and as policies and practices change, all registered pesticides continue to 

meet the statutory standard of no unreasonable adverse effects. Changes in science, public 

policy, and pesticide use practices will occur over time. Through the registration review 

program, the Agency periodically reevaluates pesticides to make sure that as these changes 

occur, products in the marketplace can continue to be used safely. Information on this program is 

provided as www.epa.gov/oppsrrd1/registration_review/. 

In 2006, the Agency implemented the registration review program pursuant to FIFRA section 

3(g) and will review each registered pesticide every 15 years to determine whether it continues to 

meet the FIFRA standard for registration. 

The iron salts registration review case includes two active chemicals, ferric sulfate and ferrous 

sulfate monohydrate. The other chemicals in this case, including ferrous sulfate heptahydrate and 

ferrous ammonium sulfate, are not found in any active US pesticide registrations. Therefore, only 

ferric sulfate and ferrous sulfate monohydrate are included in this interim decision. Iron is the 

fourth most abundant element and the second most abundant metal in the earth’s crustal rocks. 

Iron occurs in a wide variety of minerals, and it is present in foods naturally and through added 

ingredients. 

Iron salts are herbicides registered for use on outdoor lawns and ornamentals to control mosses 

in a variety of residential and commercial areas. There are no registered agricultural uses of these 

products. There are 16 registered products containing ferrous sulfate and ferric sulfate 

monohydrate. For ferrous sulfate, the end use products are formulated as a granular and applied 

by hand or spreader. For ferric sulfate monohydrate, the end use products are formulated as 

soluble concentrate/liquid and applied by sprinkler can and hose-end-sprayer. The Reregistration 

Eligibility Decision document (RED) for iron salts was completed in 1996. 
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Pursuant to 40 CFR section 155.50, EPA formally initiated registration review for iron salts (case 

4058). The following highlights significant events that have occurred during the registration 

review of iron salts: 

 December, 2008 – Publication of the iron salts Summary Document for a 60-day public 

comment period. The Summary Document included the Preliminary Work Plan (PWP) 

and was accompanied by the scoping document and problem formulation. 

 May, 2009 – Final Work Plan (FWP) for iron salts was issued – One public comment 

was received from the FIFRA Endangered Species Task Force regarding data 

compensation during the 60-day comment period for the iron salts PWP. No other 

comments were received; thus, the FWP did not modify the PWP. 

 July, 2010 – Generic Data Call-In Notice (GDCI) for iron salts was issued. The DCI 

required submission of plant toxicity, honey bee, and product chemistry data, which have 

been satisfied by the registrants. 

 September, 2014 – Proposed Interim Registration Review Decision for iron salts was 

issued – One public comment was received from the Center for Biological Diversity (the 

Center); in their comment, the Center “concurs with the EPA that there is no reasonable 

expectation for iron salts to cause direct or indirect adverse effects to threatened and 

endangered species, and will not adversely modify or destroy any listed species’ critical 

habitat. Accordingly, the Center agrees that consultations under Section 7 are not 

required for these pesticides.” No other comments were received; thus, the Interim 

Registration Review Decision did not change from the Proposed Interim Registration 

Review Decision. 

 March, 2015 – The Agency is now publishing the iron salts Interim Registration Review 

Decision, dated February 11, 2015, in docket EPA-HQ-OPP-2008-0626. 

Additional information, including this Interim Registration Review Decision, the following 

EFED risk assessment, and other supporting documents, can be found in EPA’s public 

docket for the registration review of iron salts (docket number EPA-HQ-OPP-2008-0626), 

which can be accessed at www.regulations.gov. 

 EFED Registration Review Preliminary Risk Assessment for Ferric and Ferrous Sulfates. 

E. Odenkirchen, S. Sankula. D421836. August 19, 2014. 

 HED Risk Assessment from the Reregistration Eligibility Decision. Smith, Jane. 

November 11, 1992. 

 EFED Risk Assessment from the Reregistration Eligibility Decision. Abramovich, Akiva 

D. November 27, 1992.
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II. Scientific Assessments 

 A. Human Health Assessment 

A summary of the Agency’s human health risk assessment is presented below. The Agency 

relied upon the previous iron salts human health risk assessment, HED Risk Assessment from the 

Reregistration Eligibility Decision (RED) (November, 1992), to support the registration review 

of iron salts since no significant changes have been made to impact the risk conclusions for this 

case. 

 

Hazard Characterization 

Ferric sulfate and ferrous sulfate monohydrate are generally recognized as safe by the Food and 

Drug Administration for use in food as a flavoring agent (21 CFR 184.1307) and a nutrient 

supplement (21 CFR 184.1315), respectively, with no limitation other than adherence to current 

requirements for good manufacturing practices. After consideration, the Agency found that, 

given the low toxicity of iron salts, the limited pesticidal use of these compounds, their 

widespread presence in the environment, as well as their intrinsic function in human metabolic 

pathways, no new risk assessment was needed to support the registration review for iron salts. 

Dietary Exposure Assessment 

There are no registered agricultural uses of iron salts; therefore dietary exposure from the 

registered pesticidal uses of these compounds is not expected and a dietary risk assessment is not 

required. 

Residential and Occupational Exposure 

Given the low toxicity of iron salts, the Agency concludes that any residential exposures, as well 

as mixer/loader/applicator and post application occupational risks to these compounds as a result 

of the existing uses are considered inconsequential and are not of concern.

Aggregate Risks 

EPA has no concern for aggregate risk resulting from the existing uses of iron salts, given the 

prevalence of the compounds in the environment. 

Human Incidents 

As part of the risk assessment process, EPA searched available human incident databases (the 

OPP Incident Database System (IDS) and NIOSH SENSOR-Pesticides) in January, 2015 for 

reported human incidents in the United States involving iron salts (PC codes 034902 and 

050507) from 2010 to 2015. IDS includes reports of incidents from various sources, including 

mandatory Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) Section 6 (a) (2) reports 

from registrants, other federal and state health and environmental agencies and individual 

consumers. During the 2010 – 2015 timeframe, there were three reported incidents of moderate 

severity (Main IDS) and eighteen reported incidents of minor severity (Aggregate IDS). Overall 
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there are few incidents involving iron salts reported to IDS. Symptoms reported include loss of 

appetite, chills, irregular heartbeat, erythema, and skin irritation. 

A review of SENSOR-Pesticides from 1998-2011 identifies a total of 33 single active ingredient 

(ai) cases involving iron salts (PC codes 034902 and 050507), stemming from 33 separate 

events. Thirty one of these cases were reported from Washington State. Most cases involved the 

applicator (mainly homeowner applicators) applying MossOUT (EPA Reg. No. 802-509) to their 

lawn and having ocular exposure from spray, spill, or splash. 

For more details on human incidents, please refer to the Iron Salts: Tier 1 Review of Human 

Incidents for Preliminary Risk Assessment (01/28/15), available in public docket number EPAHQ-OPP-2008-0626, which can be accessed at http://www.regulations.gov/. 

Food Tolerances 

Iron salts are not registered as pesticides for use on food and there are no US tolerances 

established for iron salts. 

 B. Environmental Assessment 

A summary of the Agency’s environmental risk assessment for iron salts is presented below. For 

detailed discussions of all aspects of the environmental risk assessment, see the Registration 

Review Preliminary Risk Assessment for Ferric and Ferrous Sulfates dated August 19, 2014, 

available in public docket number EPA-HQ-OPP-2008-0626, which can be accessed at 

http://www.regulations.gov/. 

Ecological Risk Characterization 

The 1992 risk assessment in support of the iron salts RED evaluated the current lawn and turf 

uses of these two compounds for the control of moss. These uses include granules and hose-end 

or watering can applications. The RED indicated no risk concerns for the labeled uses of ferrous 

and ferric sulfates to terrestrial vertebrates or animals, and aquatic plants. A review of the 

Problem Formulation documents’ listings of uses for the two chemicals and the summarized 

toxicological and environmental fate data indicates nothing has fundamentally changed since the 

completion of the RED risk assessment. Therefore, the Agency concludes that the finding of no 

concerns for direct effects to terrestrial vertebrates or aquatic plants and animals found 

summarized in the RED still remains accurate. 

The RED did not assess the risk to terrestrial plants for ferrous and ferric sulfates, and plant 

studies were identified as data gaps in the Problem Formulation for both chemicals. Terrestrial 

plant toxicity studies were included for vegetative vigor and seedling emergence in the Data Call 

In for Registration Review. A current understanding of the use patterns for the two chemicals 

shows that uses are confined to watered in (watering can or hose end sprayer) and granular 

applications to lawns and turf. These application scenarios are not over the top spray applications 

so spray drift loading to adjacent areas to the use site is not expected. Moreover, the Agency 

does not expect that runoff loadings will be significant to any degree because the compounds are 

expected to ionize and any resultant iron runoff is expected to be exceedingly low and largely 
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masked by natural iron background. Consequently no complete exposure pathway, drift or 

runoff, of the applied ferric sulfate or ferrous sulfate is expected to off-site plants. In light of this 

understanding of the exposure pathways for non-target plants, EPA concludes that there are no 

concerns for direct effects to terrestrial plants. 

The RED did not assess the risk to terrestrial arthropods and pollinators for ferrous and ferric 

sulfates and honeybee effects studies (the surrogate species for pollinator and arthropods risk 

assessment) were identified as data gaps in the Problem Formulation for both chemicals. A 

honey bee acute contact toxicity study was included in the Data Call In for Registration Review. 

Concerns for ferric sulfate effects on individual honey bees contacting sprayed areas are weakly 

supported by the available data. Multiple lines of evidence would suggest that both compounds 

may lethally affect bees in treated areas. Consideration of the uncertain effects thresholds, the 

low attraction of target mossy areas for bees, and the expected low geographic extent for any 

given application of the compounds applied to the intended use areas would suggest that any 

putative bee effects would not rise to a level where hives would be impacted. 

Endangered Species Assessment 

There is no reasonable expectation for any registered use of iron salts to cause direct or indirect 

adverse effects to threatened and endangered terrestrial vertebrates, terrestrial plants, terrestrial 

invertebrates, and aquatic organisms. This is because the treated area is very small relative to the 

range of species, most of the product use is expected to occur outside of areas inhabited by listed 

species, and the viscosity and very low solubility of iron salts makes it unlikely to runoff or leach 

from the target application site into non-target areas. Furthermore, since iron salts are effective 

physical repellents, listed animals are generally expected to avoid treated application sites. EPA 

has made a “no effect” determination under the Endangered Species Act (ESA) to Federally 

listed terrestrial vertebrates, terrestrial invertebrates, plants and aquatic organisms and designated 

critical habitat for such species and has therefore concluded that consultation with the Fish and 

Wildlife Service and the National Marine Fisheries Service under ESA section 7(a)(2) is not 

required for these species. 

Endocrine Disruptor Screening Program 

EPA has developed the Endocrine Disruptor Screening Program to determine whether certain 

substances (including pesticide active and other ingredients) may have an effect in humans or 

wildlife similar to an effect produced by a “naturally occurring estrogen, or other such endocrine 

effects as the Administrator may designate.” Under FFDCA section 408(p), the Agency must 

screen all pesticide chemicals. Between October 2009 and November 2010, EPA issued test 

orders/data call-ins for the first group of 67 chemicals and published a second list of chemicals 

proposed for order issuance in the future. Iron salts is not among the group of 58 pesticide active 

ingredients on the initial list nor are they proposed on the second list of chemicals to be screened 

under the EDSP. Accordingly, as part of registration review, EPA will issue future EDSP 

orders/data call-ins for registration review chemicals, including iron salts. For further 

information on the status of the EDSP, the policies and procedures, the list of 67 chemicals, 

future chemical lists proposed for screening, the test guidelines and the Tier 1 screening battery, 

please visit our website: http://www.epa.gov/endo/. 
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In the interim, EPA is making no human health or environmental safety findings associated with 

the EDSP screening of iron salts. Before completing this Registration Review, the Agency will 

make an EDSP FFDCA section 408(p) determination. 

III. Interim Registration Review Decision 

In accordance with 40 CFR Sections 155.56 and 155.58, the Agency is issuing this Interim 

Registration Review Decision. EPA’s Interim Registration Review Decision for iron salts is that 

(1) no additional data are required at this time; and (2) no changes to the affected registrations or 

their labeling are needed at this time. In addition, EPA does not expect iron salts to have direct or 

indirect adverse effects to non-listed and listed terrestrial vertebrates, terrestrial plants, terrestrial 

invertebrates, and aquatic organisms or to adversely modify any designated critical habitat for 

such species and has made a “no effect” determination under the Endangered Species Act (ESA) 

for those species and designated critical habitat for such species. This Interim Registration 

Review Decision does not cover the EDSP component of the iron salts registration review case. 

The Agency is issuing an Interim Registration Review Decision pending the completion of 

EDSP work for this case under FFDCA Section 408(p). 

IV. Next Steps and Timeline 

A. Registration Review Decision

A Federal Register Notice will announce the availability of this Interim Registration Review 

Decision for iron salts. A final decision on the iron salts registration review case will occur after 

an EDSP FFDCA section 408(p) determination has been made.