United States Prevention, Pesticides EPA 738-F-04-002
Environmental Protection and Toxic Substances September 2003
Agency (7508C)
SEPA Lactofen TRED
EPA has approved the "Report of the Food Quality Protection Act (FQPA) Tolerance
Reassessment Progress and Risk Management Decision (TRED) for Lactofen." The Federal Food,
Drug, and Cosmetic Act (FFDCA) as amended by FQPA in 1996, requires EPA to reassess all the
tolerances for registered chemicals in effect on or before the date of enactment of FQPA. In
reviewing these tolerances, the Agency must consider, among other things, aggregate risks from non-
occupational sources of pesticide exposure, whether there is increased susceptibility to infants and
children, and the cumulative effects of pesticides with a common mechanism of toxicity. The
tolerances are considered reassessed once the safety finding has been made or the tolerances are
revoked.
The Agency's TRED for lactofen includes a review of dietary exposure to lactofen from food
and drinking water. Lactofen was initially registered after 1984, and it meets the Agency's current
health and safety standards for agricultural workers and risks to nontarget organisms. Therefore, the
TRED does not address these risks. The TRED indicates that lactofen, by itself, poses no risk
concerns within the limits of the existing tolerances; therefore, no risk mitigation is needed, and no
further actions are warranted at this time. The two (2) tolerances for lactofen in/on raw agricultural
commodities are now considered reassessed as safe under section 408(q) of the FFDCA. This fact
sheet summarizes the information contained in the TRED and related documents for lactofen.
Uses
Lactofen is registered for use as an herbicide on snap beans, soybeans, cotton, kenaf, and
forestry (non-food use) for both pre- and post-emergent control of broad leaf weeds.
Lactofen is not registered for residential use. Although not currently registered, the proposed
new food uses of lactofen on peanuts and cotton were included in the risk assessment to
support the establishment of new tolerances for these two crops.
Lactofen is sold in the United States under the trade names Cobra® and Stellar®. Lactofen is
formulated as technical, manufacturing use product, and emulsifiable concentrate.
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• Lactofen may be applied by aerial and ground application; band treatment, broadcast, directed
spray, low volume spray, soil broadcast treatment, and soil incorporation. It is generally
applied at a rate of 1 Ib active ingredient (ai) per acre (A) or less per application. No more
than 1 Ib ai/A lactofen may be applied to a site in a single year.
Approximately 235,000 pounds of lactofen ai are applied annually to nearly 2.2 million acres.
Lactofen's largest markets in terms of total pounds of ai applied annually are soybeans (85%)
and cotton (12%). The remaining use is primarily on fresh beans.
Health Effects
Lactofen has low acute toxicity via the oral, dermal, and inhalation routes of exposure; causes
mild skin irritation; and is not a dermal sensitizer. The manufacturing use product is a
moderate eye irritant.
• EPA recently revised the cancer classification of lactofen based on new toxicity studies
and the Agency's 1999 Cancer Risk Assessment Guidelines. Lactofen is now
considered to be a threshold carcinogen, which means that lactofen is unlikely to be
carcinogenic at low doses and is carcinogenic only at high doses. See the lactofen
Overview document for details.
Human Health Risks
Dietary (Food and Drinking Water)
People may be exposed to residues of lactofen through food or drinking water. EPA has
assessed the dietary risk posed by lactofen and found that acute and chronic dietary risk from
food and drinking water are below the Agency's level of concern. In addition, dietary cancer
risk estimates are also below EPA's level of concern.
People may also be exposed to acifluorfen, a degradate of lactofen, in drinking water.
Because acifluorfen is also a degradate of sodium acifluorfen, another herbicide registered for
use in agricultural and residential settings, EPA included acifluorfen derived from both lactofen
and sodium acifluorfen in the drinking water assessment. The Agency does not have a concern
for drinking water exposure to the acifluorfen degradate from all sources.
Residential Risks
Lactofen is not registered for use in residential settings; therefore, a residential risk
assessment was not necessary.
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Aggregate Risk
Aggregate risk considers the combined exposure to pesticides through food, drinking
water, and, if appropriate, residential uses. Because there are no residential uses of lactofen,
there is no residential exposure to consider in the aggregate risk assessment; therefore the
aggregate assessment for lactofen includes exposures only from food and drinking water. The
aggregate risk from lactofen is not of concern.
Because lactofen degrades to acifluorfen in the environment, EPA also conducted an
aggregate risk assessment for the acifluorfen degradate from all sources. To do this, the Agency
considered the risk from combined exposures to the acifluorfen degradate from food and water
from use of both lactofen and sodium acifluorfen and exposure from the residential use of
sodium acifluorfen. EPA does not have a risk concern for aggregate risk from the acifluorfen
degradate derived from all possible sources.
Tolerance Reassessment Decisions
Tolerances for lactofen in or on raw agricultural commodities for plants are currently
established for the combined residues of lactofen and its associated metabolites, but will be
revised to include only lactofen parent. The two existing tolerances for lactofen have been
reassessed and will be lowered from 0.05 ppm to 0.01 ppm. There are currently no tolerances
for lactofen in processed commodities or animal commodities, and the available residue data
indicate that tolerances for these commodities are not necessary. No maximum residue limits
(MRLs) for lactofen have been established or proposed by Codex; therefore, there are no issues
with the compatibility of U.S. tolerances with international MRLs.
Risk Mitigation/Data Needs
Because no risks have been identified from exposure to lactofen or its acifluorfen
degradate, no risk mitigation is necessary at this time. However, the following confirmatory data
requirements have been identified for lactofen:
Prenatal Developmental Toxicity Study in Rabbits (OPPTS Guideline 870.3700, current
data gap, two developmental toxicity studies are required for every food use chemical)
• Confined Rotational Crop Study (OPPTS Guideline 860.1850, required because
confined rotational crop study in root crops indicated minimal uptake of radioactivity in
carrots and radishes planted in a field treated the previous season with lactofen).
Next Steps
A Notice of Availability of this tolerance reassessment decision document for lactofen
will be published in the Federal Register in January 2004. A copy of the 2003 TRED
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and supporting documents are available on the Agency's website at
www. gov. and www.epa.gov/pesticides/lactofen.htm.
A Data-Call In (DCI) will be issued for the confirmatory data requirements identified
above.
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