United States
Environmental Protection
Agency
Office of Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-93-002
February 1993
R.E.D. FACTS
Pesticide
Re registration
Iron Salts
All pesticides sold or used in the United States must be registered by
EPA, based on scientific studies showing that they can be used without
posing unreasonable risks to people or the environment. Because of
advances in scientific knowledge, the law requires that pesticides which
were first registered years ago be reregistered to ensure that they meet
today's more stringent standards.
In evaluating pesticides for reregi strati on, EPA obtains and reviews a
complete set of studies from pesticide producers, describing the human
health and environmental effects of each pesticide. The Agency imposes
any regulatory controls that are needed to effectively manage each
pesticide's risks. EPA then reregisters pesticides that can be used without
posing undue hazards to human health or the environment.
When a pesticide is eligible for reregi strati on, EPA announces this and
explains why in a Reregi strati on Eligibility Document, or RED. This fact
sheet summarizes the information in the RED for iron salts.
Use Profile The iron salts consist of three pesticide active ingredients that are
eligible for reregi strati on: Iron (III) sulfate, Iron (II) sulfate monohydrate,
and Iron (II) sulfate heptahydrate.
Iron salts are registered for use as herbicides to control moss on
lawns, turf, ornamental herbaceous plants, woody shrubs and vines.
Registered products are formulated as soluble concentrates and granulars.
They are applied by sprinkler can, hose-end sprayer, spreader, or by hand.
The major use of iron salts in the United States is non-pesticidal, as a
fertilizer micronutrient. Iron salts also are used as an electrolyte in dry cell
batteries, as an animal feed additive, as a galvanizer and as an emulsion-
breaker. They have further uses in water purification and sewage treatment,
and in textile dying and calico printing.
Regulatory Iron salts first were registered as pesticides in 1962. In addition to the
History current outdoor moss control uses, iron salts were registered previously for
use inside households, and in and around commercial, institutional and
industrial premises.
At present, a total of 13 products are registered containing iron salts
as sole or one of several active ingredients; one product contains Iron (III)
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Human Health
Assessment
sulfate, nine contain Iron (II) sulfate monohydrate, and three contain Iron
(II) sulfate heptahydrate.
A fourth active ingredient, Iron II ammonium sulfate, is not being
supported for reregi strati on and so is not covered in this RED.
Toxicity
Iron salts are present normally in the environment. Iron is the fourth
most abundant element and the second most abundant metal in the earth's
crystal rocks. Iron occurs in a wide variety of minerals, and is present in
foods naturally and through added ingredients.
The iron salts are of low acute toxicity through oral, dermal and
inhalation routes of exposure. They have been placed in Toxicity Category
III for these effects. Although a mutagenicity study using microorganisms
showed positive results, it is unlikely that such effects would result in
humans or other mammals at the levels of exposure expected from the use
of iron salts as pesticides. Other toxicity studies normally required for
reregi strati on were not necessary to evaluate the risks of the iron salts.
Dietary Exposure
Dietary exposure is not expected to result from use of the iron salts as
pesticides. No food or feed-related uses are registered, and no tolerances
(maximum residue limits) or exemptions from the requirement of a
tolerance are established. Further, the iron salts are generally recognized as
safe (GRAS) by the Food and Drug Administration for use as a flavoring
agent and nutrient supplement in foods (please see 40 CFR 180.2(a)).
Occupational and Residential Exposure
The potential for mixer, loader and applicator exposure exists when
liquid or granular iron salts products are applied to lawns, turf and other
outdoor sites using spreaders, sprinkler cans or by hand. However, these
inorganic salts are of little concern from a toxicity perspective. Any
exposure of mixers, loaders or applicators is considered inconsequential.
Human Risk Assessment
The risks to people from dietary, occupational and residential
exposure to iron salts pesticides are considered negligible. It is general
knowledge that these compounds are of low toxicity. They are intentionally
added to foods as flavoring agents and nutrient supplements, and they have
an inherent function in the metabolic systems of humans and domestic
animals.
Environmental Environmental Fate
Assessment The environmental fate and transport of iron salts is dominated by
three processes: the conversion of Iron (II) to Iron (III), the formation of
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insoluble oxides and hydroxides that also are well known components of
soils, and the distinct surface chemistry of the iron salts that causes their
adsorption with other soil components, forming larger soil particles.
Use of the iron salts produces iron oxides and hydroxides that are no
different from those normally found in soils, and which give them their
brown and red colors. Although certain bacteria can reduce Iron (III) to the
more mobile Iron (II), this is rapidly immobilized.
Therefore, the use of iron salts as herbicides to control moss is not
expected to contribute significantly to the chemistry and fate of the
compounds existing naturally in the environment. No unreasonable effects
are expected from the use of these pesticide products as directed.
Ecological Effects
In dietary acute toxicity studies, iron salts are practically nontoxic to
bird species and are nontoxic or slightly toxic to rats. Iron (II) sulfate
heptahydrate, the most toxic form of the iron salts compounds, is
moderately toxic to aquatic invertebrates and slightly toxic to fish.
No adverse effects to avian, mammalian or aquatic populations are
anticipated from the use of iron salts. Iron is one of the earth's most
abundant elements, and it is immobilized at the pH range of 5-9. Runoff to
aquatic systems is unlikely since the parent compounds convert very rapidly
to less soluble forms in the environment. Furthermore, the oxidized iron
compounds bind tightly to soil under turf.
No adverse effects to endangered species are anticipated from the use
of iron salts.
Additional Data
Required
EPA is requiring additional physical chemistry studies as confirmatory
data and to complete the generic data base for iron salts. Product-specific
product chemistry studies and revised labeling also are required for
reregi strati on. These additional studies are being required through Data
Call-Ins issued in conjunction with the iron salts RED.
Product Labeling
Changes Required
The labels of all registered iron salts products must comply with
EPA's current pesticide labeling requirements. In addition, to protect
surface waters, end-use product labels must bear the following
Environmental Hazards statement:
"Do not apply directly to water, or to areas where surface water is
present or to intertidal areas below the mean high water mark. Do not
contaminate water when disposing of equipment washwater or
rinsate."
Regulatory * The three pesticide active ingredients discussed in the iron salts
Conclusion RED will not result in unreasonable adverse effects to human health or the
environment, and all registered products containing these active ingredients
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For More
Information
are eligible for reregi strati on. These products will be reregistered once the
required generic and product-specific data and revised labeling are received
and accepted by EPA.
• Registered products containing iron salts as well as other active
ingredients will be reregistered once the other active ingredients also are
determined to be eligible for reregi strati on.
EPA is requesting public comments on the Reregi strati on Eligibility
Document (RED) for iron salts during a 60-day time period, as announced
in a Notice of Availability published in the Federal Register. To obtain a
copy of the RED or to submit written comments, please contact the
Pesticide Docket, Public Response and Program Resources Branch, Field
Operations Division (7506C), Office of Pesticide Programs (OPP), US
EPA, Washington, DC 20460, telephone 703-305-5805.
Following the comment period, the iron salts RED will be available
from the National Technical Information Service (NTIS), 5285 Port Royal
Road, Springfield, VA 22161, telephone 703-487-4650.
For more information about iron salts or about EPA's pesticide
reregi strati on program, please contact the Special Review and Reregi strati on
Division (7508W), OPP, US EPA, Washington, DC 20460, telephone 703-
308-8000. For information about reregi strati on of individual iron salts
products, please contact Joanne Miller, Product Manager, Registration
Division (7505C), OPP, US EPA, Washington, DC 20460, telephone 703-
305-7830.
For information about the health effects of pesticides, or for assistance
in recognizing and managing pesticide poisoning symptoms, please contact
the National Pesticides Telecommunications Network (NPTN). Call toll-
free 1-800-858-7378, between 8:00 am and 6:00 pm Central Time, Monday
through Friday.
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