Request for Additional Information and Risk Management Suggestions for
the

Reregistration of Chlorflurenol

Phase 3 Public Comment Period

October 25, 2006

	 The Environmental Protection Agency (EPA) is developing a
Reregistration Eligibility Decision (RED) for chlorflurenol, an
herbicide and plant growth regulator, through a 4-phase public
participation process that the Agency uses to involve the public in
developing pesticide reregistration decisions.  During Phase 3 of the
process, the Agency seeks public comment on all elements of the
Agency’s risk assessments and supporting documents.  The Agency is
particularly seeking use and usage information, data refinement, and
risk management ideas or proposals to address the risks identified in
the Agency’s risk assessments.

Chlorflurenol is a nonfood use herbicide, plant growth retardant, and
plant growth regulator used in agricultural, commercial, and residential
settings.  As an herbicide or plant growth retardant, it is used for the
postemergent control of annual grasses, broadleaf weeds, trees, shrubs
and vines for nonagricultural rights-of-way (i.e., utility lines),
lawns, ornamental turf (including golf courses and parks), and high
density forestry management areas.  As a plant growth regulator,
chlorflurenol is used in the production of pineapple planting material
(sliplets); this use is considered to be nonfood as no finite residues
are expected.  

For the uses of chlorflurenol being considered for reregistration, the
Agency is seeking answers to the following questions:

Use and Usage

A complete analysis of the current labeling and available use
information for chlorflurenol was not possible due to lack of
information regarding the frequency of application and the number of
applications per season. What are the typical application intervals and
the number of applications per season for each use pattern?

How many pounds of chlorflurenol active ingredient are applied to each
use site per year?

How important is chlorflurenol to pineapple growers for pineapple
propagation? 

Chlorflurenol Alternatives

What other pesticides or treatments can be used commercially to control
pests that are controlled by chlorflurenol?

What other pesticides or treatments can be used commercially to produce
planting material for pineapples? 

Human Health Exposure and Risk Estimates of Concern

A complete discussion of human health exposures and risks from
registered uses of chlorflurenol is presented in the Chlorflurenol
Methyl Ester: HED Chapter of the Reregistration Eligibility Decision
Document (RED) dated July 10, 2006.

No increased fetal susceptibility was observed in chlorflurenol prenatal
studies with rats and rabbits.  However, a 1973 three-generation
reproduction study showed equivocal litter size and pup weight decrement
at birth and subfertility in adult offspring, but showed a poor dose
response.  Due to these ambiguous findings in the reproduction study, an
additional uncertainty factor of 3X was used when calculating human oral
risk.  

No chlorflurenol dermal absorption studies were available for use in the
risk assessment.  This resulted in the assumption of 100% dermal
absorption from an oral study endpoint for use in assessing dermal
exposure. 

Are there any additional reproduction studies for chlorflurenol that may
help refine the human health risk assessment?

 Are there any dermal absorption studies for chlorflurenol that may help
assess dermal exposure?

Human health risks of concern associated with the use of chlorflurenol
are: 

1) occupational dermal risks from applying liquid sprays with
rights-of-way equipment to the following use sites: 

to turf growing in culverts, rights of way, median strips, ditches,
and/or under security fences at the 3 lb a.i./A rate;

to non-agricultural rights-of-ways/fence rows and hedge rows at the 3 lb
a.i./A rate;

to gymnosperms and hardwoods at the 5 lb a.i./A rate;

to shrubs, shade trees and vines at the 4.5 lb a.i./A rate; and

to high density forestry management at the 4.0 lb a.i./A rate.

Risks remain a concern at maximum personal protective equipment and no
engineering controls are available for rights-of-way application
equipment;

2) residential postapplication dermal risks for adults at 3 lbs a.i./A;

3) residential postapplication risks to toddlers from high contact
activity on lawns at the 1.0/1.1 lb a.i./A and 3.0 lb a.i./A application
rates;  

4) residential risks to infants from chronic exposure to drinking water
using modeled ground water estimated concentrations.  The assessment for
ground water showed that the highest estimated exposure was 176% of the
chronic RfD for non-nursing infants and 142% of the chronic RfD for all
infants (< 1 year);

5) potential postapplication exposure to golf course workers.  For golf
course turf at the 1.0 and 1.1 lb a.i./A rates for sprays and granular
applications respectively and assuming 100% dermal absorption, risks are
not a concern for hand weeding and transplanting tasks at day 4 for
liquid formulations and at day 5 for granular formulations.  Using the
3.0 lb a.i./A rates for sprays and granular applications and assuming
100% dermal absorption, risks are not a concern for hand weeding and
transplanting tasks at day 14 and for mowing at day 8.  

Are there any additional data with which to assess the potential
occupational and residential dermal risks associated with the use of
chlorflurenol?

Are there any additional data with which to refine potential drinking
water risks from potential contamination of ground water? 

Are the above reentry intervals (REIs) for golf course workers
acceptable for hand weeding, transplanting and mowing activities?

What risk management ideas or proposals might address the above risks?

Environmental Fate 

A complete discussion of environmental fate and ecological exposures and
risks from registered uses of chlorflurenol is presented in the
Environmental Fate and Ecological Risk Assessment for Chlorflurenol
Methyl Ester, dated June 30, 2006.

The environmental persistence of chlorflurenol is difficult to determine
with any certainty due to the limited number of studies available and
the deficiencies within these studies.  Based on these limited data,
chlorflurenol appears to be highly to very highly mobile in soil and
hydrolytically stable at pH 6.  

Are there any additional data with which to assess the environmental
persistence of chlorflurenol?

Potential Risk to Nontarget Organisms

There is a great amount of uncertainty in the potential for risk to
non-target organisms, particularly freshwater and estuarine/marine fish
and invertebrates, and non-target plants, due to lack of data with which
to conduct a risk assessment.  Limited data suggest potential chronic
risk to mammals for species that feed on short grass, tall grass, and
broadleaf plants/small insects.

Are there any additional data with which to assess the risks to
nontarget organisms from the use of chlorflurenol?

What risk management ideas or proposals might address potential chronic
risks to mammals?

