[Federal Register Volume 79, Number 19 (Wednesday, January 29, 2014)]
[Pages 4691-4693]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2014-01234]

[[Page 4691]]



[EPA-HQ-OPP-2013-0676; FRL-9903-12]

Pesticides; Consideration of Spray Drift in Pesticide Risk 
Assessment: Notice of Availability and Request for Comment

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.


SUMMARY: EPA is announcing the availability of two draft guidance 
documents for public comment. These documents describe how off-site 
spray drift will be evaluated for ecological and human health risk 
assessments for pesticides. Once final, these guidance documents will 
be posted on EPA's Web site, to ensure consistent risk assessment 
practices and provide transparency for pesticide registrants and other 
interested stakeholders.

DATES: Comments must be received on or before March 31, 2014.

ADDRESSES: Submit your comments, identified by docket identification 
(ID) number EPA-HQ-OPP-2013-0676, by one of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 
Follow the online instructions for submitting comments. Do not submit 
electronically any information you consider to be Confidential Business 
Information (CBI) or other information whose disclosure is restricted 
by statute.
     Mail: OPP Docket, Environmental Protection Agency Docket 
Center (EPA/DC), (28221T), 1200 Pennsylvania Ave. NW., Washington, DC 
     Hand Delivery: To make special arrangements for hand 
delivery or delivery of boxed information, please follow the 
instructions at http://www.epa.gov/dockets/contacts.htm.
    Additional instructions on commenting or visiting the docket, along 
with more information about dockets generally, is available at http://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: For the ecological risk assessment 
guidance document, Faruque Khan, Environmental Fate and Effects 
Division, (7507P), Office of Pesticide Programs, Environmental 
Protection Agency, 1200 Pennsylvania Ave. NW., Washington, DC 20460-
0001; telephone number: (703) 305-6127; email address: 
    For the human health risk assessment guidance document, Jeff 
Dawson, Health Effects Division, (7509P), same address; telephone 
number: (703) 305-7329; email address: dawson.jeff.@epa.gov.


I. General Information

A. What is the Agency's authority for taking this action?

    Pesticides are regulated under both the Federal Insecticide, 
Fungicide and Rodenticide Act (FIFRA), 7 U.S.C. 136 et. seq., and 
section 408 of the Federal Food, Drug, and Cosmetic Act (FFDCA) 21 
U.S.C. 346a.

B. Does this action apply to me?

    you may be potentially affected by this action if you are a 
producer of pesticide products (NAICS 32532), importers of such 
products, or any person or company who seeks to obtain a tolerance for 
such a pesticide. The North American Industrial Classification System 
(NAICS) code is not intended to be exhaustive, but rather provides a 
guide to help readers determine whether this document applies to them. 
Other types of entities not listed could also be affected.

C. What should I consider as I prepare my comments for EPA?

    1. Submitting CBI. Do not submit this information to EPA through 
regulations.gov or email. Clearly mark the part or all of the 
information that you claim to be CBI. For CBI information in a disk or 
CD-ROM that you mail to EPA, mark the outside of the disk or CD-ROM as 
CBI and then identify electronically within the disk or CD-ROM the 
specific information that is claimed as CBI. In addition to one 
complete version of the comment that includes information claimed as 
CBI, a copy of the comment that does not contain the information 
claimed as CBI must be submitted for inclusion in the public docket. 
Information so marked will not be disclosed except in accordance with 
procedures set forth in 40 CFR part 2.
    2. Tips for preparing your comments. When submitting comments, 
remember to:
    i. Identify the document by docket ID number and other identifying 
information (subject heading, Federal Register date and page number).
    ii. Follow directions. The Agency may ask you to respond to 
specific questions or organize comments by referencing a Code of 
Federal Regulations (CFR) part or section number.
    iii. Explain why you agree or disagree; suggest alternatives and 
substitute language for your requested changes.
    iv. Describe any assumptions and provide any technical information 
and/or data that you used.
    v. If you estimate potential costs or burdens, explain how you 
arrived at your estimate in sufficient detail to allow for it to be 
    vi. Provide specific examples to illustrate your concerns and 
suggest alternatives.
    vii. Explain your views as clearly as possible, avoiding the use of 
profanity or personal threats.
    viii. Make sure to submit your comments by the comment period 
deadline identified.

D. What action is the Agency taking?

    Pesticide drift can be characterized as the physical movement of a 
pesticide through the air at the time of application or soon thereafter 
from the target site to any non- or off-target site. This does not 
include pesticide movements by erosion, migration, volatility, or 
windblown soil particles after application. Drift is dependent on the 
design of application equipment, size of spray droplets or dry 
particles, weather conditions, and other factors.
    Once off-target, pesticide drift can potentially deposit in 
unintended areas or directly onto people or nontarget species. To 
provide guidance to EPA staff and stakeholders, EPA has developed two 
documents describing EPA's approach to assessing pesticide drift in 
human health and ecological risk assessments. Both documents are 
available in the docket for this action using the docket identifier 
     Guidance on Modeling Offsite Deposition of Pesticides via 
Spray Drift for Ecological and Drinking Water Assessments for the 
Environmental Fate and Effects Division (Draft dated 11/1/2013) (Ref. 
1), and
     Residential Exposure Assessment Standard Operating 
Procedures (SOPs), Addenda 1: Consideration of Spray Drift (Draft dated 
11/1/2013) (Ref. 2).
    The draft Ecological and Drinking Water Assessment Guidance 
provides information on estimating spray drift fractions of liquid 
sprays for modeling offsite deposition of a pesticide for ecological 
and drinking water assessment and on estimating distances from the 
treated field where adverse effects may be observed due to exposure to 
spray drift. The draft guidance also provides default assumptions for 
modeling inputs to use when estimating spray drift in terrestrial and 
aquatic assessments.
    The Residential Exposure Addenda describes a screening approach for 
defining when assessments are needed and the methodology for estimating 
risks for indirect exposures to pesticide drift, such as children 
playing on a lawn that has pesticide residues that drifted from a 
nearby treated field. The draft

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guidance describes when quantitative risk assessments for spray drift 
are generally needed, and also provides the modeling inputs needed to 
complete the exposure and risk assessments.
    EPA expects the model-generated values for spray drift fractions to 
provide realistic exposure and risk estimates for both ecological and 
human health assessments. These policies will promote consistency 
within EPA, as well as with other federal agencies and international 
regulatory partners that rely on predicted spray drift values.

II. Spray Drift Estimates Used for Risk Assessment

    EPA uses two peer-reviewed spray drift models (AgDRIFT and AGDISP) 
to estimate the contribution of spray drift to ecological and human 
health risk assessments. Both models estimate drift fractions, as 
applicable to spray of liquid materials. In general, OPP uses the 
AgDRIFT model to assess spray drift from agricultural applications, 
whereas AGDISP is used for other types of pesticide applications, such 
as aerial application of mosquito adulticides. It is noted that AGDISP 
has limited capability to estimate drift fractions from dry materials 
    EPA has prepared a support document (Ref. 3), which is available in 
the docket for this action, explaining the scientific basis for AgDRIFT 
and AGDISP, and providing information on this harmonized approach for 
estimating spray drift fractions.

III. Consideration of Spray Drift in Ecological Risk Assessment

    To enhance consistency and provide more realistic risk estimates, 
the Agency has developed the draft ecological guidance (Ref. 1) to 
apply a uniform approach for estimating drift fractions for all tiers 
of ecological risk assessments. Unit III. provides historical 
information on OPP's approach for estimation of spray drift.
    Prior to the adoption of AgDRIFT and AGDISP, for aquatic exposure 
assessment purposes, default values of 5% were recommended to OPP for 
use as estimates for the spray drift loading from aerial and air-blast 
applications to a pond (Ref. 4). However, beginning in the 1990s, OPP's 
practice was to use default drift values--developed using best 
professional judgement--of 5% (aerial application), 3% (airblast 
application), and 1% (ground application) in terrestrial and aquatic 
assessments. Then, to make more realistic calculations of exposure from 
spray drift deposition, EPA implemented the use of AgDRIFT model-
generated values for spray drift fractions for:
     Screening-level (Tier I) aquatic exposure model GENEEC 
(GENeric Estimated Exposure Concentration) for ecological exposure 
assessments, and
     Tier I--FIRST (FQPA Index Reservoir Screening Tool) and 
Tier II--PRZM (Pesticide Root Zone Model)/EXAMS (Exposure Analysis 
Modeling System) for drinking water assessments.
    However, the practice of using default drift values of 5% (aerial 
application), 3% (airblast application), and 1% (ground application) in 
terrestrial and Tier II aquatic assessments continued.
    In 2004, EPA staff performed a comparison study of these 
previously-specified, percentage-based default spray drift deposition 
levels and AgDRIFT predictions. The comparison indicated these default 
values can potentially underestimate off-site deposition of spray drift 
under certain scenarios when compared to model-predicted values (Ref. 
    Based upon continued model refinements, EPA is now revising its 
approach for terrestrial and Tier II aquatic assessments. As a result 
of these revisions, EPA has developed default model input parameters to 
estimate the spray drift fraction for all tiers of aquatic and 
terrestrial exposure assessments. Use of these inputs in the AgDRIFT 
model should result in more realistic estimates of exposure from spray 
drift deposition for all terrestrial and aquatic environments.

IV. Consideration of Spray Drift in Human Health Risk Assessment

    The draft guidance for considering spray drift in human health risk 
assessment has been developed as an addendum to the EPA's existing SOPs 
For Residential Exposure Assessment (SOPs), which are available at 
EPA routinely uses the SOPs as the basis for evaluating the risks 
associated with residential exposures to pesticides, including 
residential turf assessments.
    The predominant sources of potential human health risks associated 
with spray drift is from direct contact with sprays and from contact 
with contaminated surfaces such as lawns in areas adjacent to pesticide 
applications. Direct contact with sprays is considered a violation of 
standard label language, and as applicable, EPA's Worker Protection 
Standard (40 CFR part 170). This means that direct contact is not 
evaluated in risk assessment but is addressed through enforcement 
action against persons not complying with label prohibitions/
directions, through applicator education, and through other means. The 
primary focus on spray drift in the human health risk assessment 
process is through indirect contact with contaminated surfaces such as 
lawns. The draft guidance document describes scenarios for which 
quantitative risk assessments for spray drift would generally be 
appropriate, and provides the information needed to complete a 
residential turf assessment using spray drift fractions predicted by 
    Spray drift is governed by a variety of factors which govern how 
much of the pesticide application deposits on surfaces where contact 
with residues can eventually lead to indirect exposures (e.g., children 
playing on lawns that are next to treated fields and where residues 
have deposited). The potential risk estimates from these residues can 
be calculated using drift modeling coupled with methods employed for 
residential risk assessments for turf products. There is a regulatory 
precedent for this approach as it has been used by the Agency in a 
number of previous situations that include:
     Response to a petition to cancel 14 pesticides, (69 FR 
30042; May 26, 2004; FRL-7355-7),
     Development of buffer zone estimates for two 
organophosphate insecticides used on orchard crops in the Pacific 
Northwest, and
     Development of a recent spray drift risk assessment for 
all uses of an organophosphate insecticide, available at http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2008-0850-0105.
    Using default assumptions, the AgDRIFT model is used to predict 
spray drift estimates (similar to the ecological assessment process 
described in Unit III.) in the absence of application parameters such 
as droplet size spectrum, release height, wind speed, and percent of 
swath displacement (i.e., the same Tier 1 input parameters are used to 
compute drift fractions for both human health and ecological risk 
assessment). In the human health risk assessment process, deposition 
estimates are integrated over 50 feet wide lawns to account for the 
fact that small children can play anywhere on an impacted lawn. In the 
draft guidance document (Ref. 2), drift estimates are then used to 
adjust deposition values for the standard methods for evaluating 
children's exposure from treated turf. Small children are the focus of 
this methodology because they have the highest exposures. Values are 
calculated using lawns at different distances away from a treatment 
area--adjoining it to 300 feet away. Also, additional spray

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drift deposition values are included which account for more options 
available in the AgDRIFT model which allows for flexibility in the risk 
management process. These include:
     All canopy types for orchard airblast sprayers,
     All boom height and spray quality combinations available 
for groundboom sprayers, and
     Different options for aircraft including consideration of 
helicopter use and differing spray qualities (e.g., coarse instead of 
fine to medium spray quality).

V. Request for Comment

    EPA is providing an opportunity, through this notice, for the 
public to provide comments and input on any additional information that 
may impact the Agency's assessment of spray drift in pesticide risk 
assessments. Specifically included within the Agency's request for 
comments are the model-generated spray drift values as described in 
either or both of the draft guidance documents.
    With regards to the Ecological and Drinking Water Assessment 
Guidance, as discussed in Unit III., EPA currently uses spray drift 
estimates, developed in the 1990s, using best professional judgement: 
5% (aerial application), 3% (air-blast application) and 1% (ground 
application) in selected terrestrial and Tier II aquatic exposure 
assessments. Based upon continued model refinements, EPA is revising 
this approach and is beginning to incorporate AgDRIFT model estimates 
in all tiers for terrestrial and aquatic environments to estimate more 
realistic exposure from spray drift deposition. This approach is more 
consistent with current approaches throughout OPP. EPA is seeking 
comment on this approach.
    While EPA does not intend to formally respond to all comments made, 
comments in response to this notice will be taken into consideration as 
EPA finalizes these guidance documents. If substantive comments are 
made that may substantially change the EPA's consideration of spray 
drift in pesticide risk assessment, EPA will notify the public of these 
comments and describe how EPA has responded to them.

VI. References

    As indicated under ADDRESSES, a docket has been established for 
this notice under docket ID number EPA-HQ-OPP-2013-0676. The following 
is a listing of the documents that are specifically referenced in this 
action. The docket includes these documents and other information 
considered by EPA, including documents that are referenced within the 
documents that are included in the docket, even if the referenced 
document is not physically located in the docket. For assistance in 
locating these other documents, please consult the persons listed under 

1. USEPA. Guidance on Modeling Offsite Deposition of Pesticides via 
Spray Drift for Ecological and Drinking Water Assessments for the 
Environmental Fate and Effects Division (Draft dated 11/1/2013).
2. USEPA. Residential Exposure Assessment Standard Operating 
Procedures (SOPs), Addenda 1: Consideration of Spray Drift (Draft 
dated 11/1/2013).
3. USEPA. Use of AgDRIFT and AGDISP in OPP Risk Assessments.
4. RESOLVE. 1992. Improving Aquatic Risk Assessment under FIFRA: 
Report of the Aquatic Effects Dialogue Group. Published by World 
Wildlife Fund, Suite 500, 1250 24th Street NW., Washington, DC 
5. Birchfield N B. 2004. Pesticide spray drift and ecological risk 
assessment in the U.S. EPA: A comparison between current default 
spray drift deposition levels and AgDRIFT predictions in screening-
level risk assessments. Aspects of Applied Biology 71: 125-131.

List of Subjects

    Environmental protection, Administrative practice and procedure, 
Agricultural commodities, Pesticides and pests.

    Dated: January 13, 2014.
Steve Bradbury,
Director, Office of Pesticide Programs.
[FR Doc. 2014-01234 Filed 1-28-14; 8:45 am]