Docket Number EPA-HQ-OPP-2010-0923 

www.regulations.gov 

Chlorpropham Summary Document 

Registration Review: Initial Docket 

December 2010 

 

TABLE OF CONTENTS

I. Preliminary Work Plan (PWP) ....................................................................4 

II. Fact Sheet .....................................................................................................11 

III. Summary of Data Gaps...............................................................................17 

__________________________________________________________________ 

Please Note 

This Preliminary Work Plan and Fact Sheet summarize the Environmental Protection Agency’s 

current position on chlorpropham based on the following documents: 

1. Registration Review: Preliminary Problem Formulation for Environmental Fate and 

Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments for 

Chlorpropham. Dated November 4, 2010. 

2. Chlorpropham. Human-Health Assessment Scoping Document in Support of Registration 

Review. Dated November 2, 2010. 

3. Appendix A: Label, Use, and Usage Table. Dated March 5, 2010.

4. Chlorpropham: Review of Human Incidents. Dated August 20, 2010. 

5. Waiver Review on Generic DCI Regarding Chlorproham for Use on Easter Lilies and 

Ginkgo Trees. Dated September 20, 2001.

6. Report of FQPA Tolerance Reassessment Progress and Interim Risk Management Decision 

for Chlorpropham. Dated September 2002.

These and other supporting documents for the chlorpropham registration review case may be 

found in the docket EPA-HQ-OPP-2010-0923 at http://www.regulations.gov. 

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I. Preliminary Work Plan – Chlorpropham 

Introduction: 

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. All 

pesticides distributed or sold in the United States (U.S.) generally must be registered by the 

Environmental Protection Agency (EPA or the Agency), based on scientific data showing that 

they will not cause unreasonable risks to human health or the environment when used as directed 

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

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

meet the statutory standard of no unreasonable adverse effects to human health or the 

environment. 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 change occurs, products in the marketplace can be used safely. Information on this 

program is provided at: http://www.epa.gov/oppsrrd1/registration_review/. 

The Agency is implementing the registration review program pursuant to Section 3(g) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and will review each registered 

pesticide every 15 years to determine whether it continues to meet the FIFRA standard for 

registration. The Agency will consider benefits information and data as required by FIFRA. The 

public phase of registration review begins when the initial docket is opened for each case. The 

docket is the Agency’s opportunity to state what it knows about the pesticide and what additional 

risk analyses and data or information it believes are needed to make a registration review 

decision. After reviewing and responding to comments and data received in the docket during 

this initial comment period, the Agency will develop and commit to a final work plan and 

schedule for the registration review of chlorpropham. 

Chlorpropham is a carbamate plant growth regulator registered for use for sprout control on postharvest, stored potatoes. Also, Special Local Need (SLN) registrations for chlorpropham allow 

chlorpropham use to prevent bud formation on ginkgo trees in Washington, D.C. and to prevent 

bud formation and control Botrytis on Easter lilies in California and Oregon. There are currently 

no residential uses for chlorpropham. The Reregistration Eligibility Decision (RED) for 

Chlorpropham was completed in October 1996 and the Report of FQPA Tolerance Reassessment 

Progress and Interim Risk Management Decision (TRED) for Chlorpropham was completed in 

September 2002.

Anticipated Risk Assessment and Data Needs:

The Agency anticipates the need to require data and conduct an ecological risk assessment for 

chlorpropham, including an endangered species assessment. For human health, revised dietary 

and occupational risk assessments may be needed during registration review to incorporate 

updated toxicological endpoints, exposure estimates, and data anticipated to be required through 

a registration review data call-in. Below is a summary of the issues relevant to the registration 

review of chlorpropham. 

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Ecological Risk: 

• In past assessments, due to the limited amount of outdoor chlorpropham use, the potential 

for chlorpropham to enter the environment has been assumed to be low. Consequently, 

the Agency has not previously conducted an environmental fate and ecological risk 

assessment for chlorpropham. A summary of the available environmental fate and effects 

data was prepared in support of the 1996 RED. 

• An ecological risk assessment of all registered uses of chlorpropham will be conducted 

during registration review. The new assessment will incorporate the most up-to-date 

modeling methodologies, updated toxicological endpoints, and data submitted under the 

anticipated registration review data call-in. 

• The Agency has not conducted an ecological risk assessment that supports a complete 

endangered species determination for chlorpropham. The ecological risk assessment 

planned during registration review will allow the Agency to determine whether 

chlorpropham’s use has “no effect” or “may affect” federally listed threatened or 

endangered species (listed species) or their designated critical habitats. When an 

assessment concludes that a pesticide’s use “may affect” a listed species or its designated 

critical habitat, the Agency will consult with the U.S. Fish and Wildlife Service and/or 

National Marine Fisheries Service (the Services), as appropriate. 

• Data gaps exist in the environmental fate and toxicity databases for chlorpropham. The 

Agency had previously required through Data Call-In Notice GDCI-018301-17712, 

issued in December 1996, a number of environmental fate and ecological effects studies 

as confirmatory data for the chlorpropham RED. However, the Agency waived these 

study requirements after the registrant voluntarily cancelled the use of chlorpropham on 

spinach. The justification for waiving the study requirements was also based on the very 

limited use of chlorpropham on Easter lilies and ginkgo trees, and the determination that 

available data for structurally similar herbicides, propanil and propham, could be used as 

surrogate data for chlorpropham. However, based on current environmental fate and 

ecological risk assessment standards, data are needed for the registration review 

assessment of chlorpropham. 

• EPA anticipates requiring the following guideline studies in order to conduct a 

comprehensive ecological risk assessment, including an endangered species assessment, 

for the registration review of chlorpropham. 

 Guideline No. 835.1230 – Sediment and Soil Absorption/Desorption 

 Guideline No. 835.1240 – Soil Column Leaching 

 Guideline No. 835.4100 – Aerobic Soil Metabolism 

 Guideline No. 850.1300 – Daphnid Chronic Toxicity 

 Guideline No. 850.1400 – Fish Early-Life Stage Toxicity, freshwater 

 Guideline No. 850.2100 – Avian Acute Oral Toxicity, Passerine 

 Guideline No. 850.2300 – Avian Reproduction 

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 Guideline No. 850.4100 – Terrestrial Plant Toxicity: Tier 2 seedling emergence1

 Guideline No. 850.4150 – Terrestrial Plant Toxicity: Tier 2 vegetative vigor1

 Guideline No. 850.4400 – Aquatic Plant Toxicity, Tier 21

 Guideline No. 850.5400 – Algal Toxicity, Tier 21

• The Agency seeks additional information, particularly use and usage information, in 

order to conduct a refined, complete ecological risk assessment, including an endangered 

species assessment for chlorpropham. See the “Guidance for Commenters” section 

below. 

• Please refer to the November 4, 2010 document Registration Review: Preliminary 

Problem Formulation for Environmental Fate and Ecological Risk, Endangered Species, 

and Drinking Water Exposure Assessments for Chlorpropham in the registration review 

docket (EPA-HQ-OPP-2010-0923) for a detailed discussion of the anticipated risk 

assessment and data needs. 

Human Health Risk: 

• The most recent human health risk assessment, including an updated drinking water 

assessment, was completed in 2002 in support of the chlorpropham TRED. 

• During registration review, the Agency anticipates conducting a new drinking water 

assessment for the Easter lily use and the amount of chlorpropham that deposits from the 

aerial release into the environment from the stored potato use. 

• The Agency anticipates conducting a new dietary risk assessment, incorporating refined 

estimated drinking water concentrations (EDWCs), updated anticipated residues, and 

Pesticide Data Program (PDP) data. 

• The chlorpropham tolerance expression will be reviewed during registration review to 

ensure that it appropriately covers the metabolites and degradates of chlorpropham and 

that it specifies the residues to be measured for each commodity. 

• The residue chemistry database is sufficient to support the current registrations; however, 

there are some outstanding data requirements concerning the analytical methods. These 

data were required by a previous Data Call-in (DCI) for chlorpropham issued in April 

1994. These data, when submitted, will complete the residue chemistry data 

requirements for chlorpropham. The overdue, outstanding data are: 

 

1 The Agency anticipates requiring a Tier II study. The anticipated Data Call-In Notice will note that a 

Tier I study may be conducted in lieu of a Tier II study with the understanding that adverse effects (even 

if <25%) would necessitate a Tier II study as well. The purpose of a Tier II study is to establish either a 

No Observed Adverse Effect Concentration (NOAEC) or a concentration at which there is a 5% observed 

effect (EC05) to be used in an endangered species risk assessment for nontarget plants. If neither an 

NOAEC nor an EC05 value is available, then the Agency may have to presume that chlorpropham “may 

affect” listed nontarget plant species in the registration review endangered species risk assessment.

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 A revised analytical method for tolerance enforcement in stored potato 

commodities. 

 Independent laboratory validation for the enforcement method to detect 

chlorpropham and its 4-HAS metabolite in meat and milk. 

• Occupational exposures have not been previously assessed for airblast application to 

ginkgo trees and for the post-application use on Easter lilies. In addition, the previously 

assessed occupational handler exposure scenarios did not include estimates of inhalation 

exposure. Therefore, the Agency anticipates conducting a revised occupational exposure 

assessment during registration review. 

• EPA anticipates requiring the following guideline studies in order to complete the 

toxicity database for chlorpropham and conduct a complete human health risk assessment 

for the registration review of chlorpropham: 

 Guideline No. 870.3465 90-day Inhalation-Toxicity1

 Guideline No. 870.6200 Acute and Subchronic Neurotoxicity 

 Guideline No. 870.7800 Immunotoxicity 

• Please refer to the November 2, 2010 document Chlorpropham. Human-Health 

Assessment Scoping Document in Support of Registration Review in the registration 

review docket (EPA-HQ-OPP-2010-0923) for a detailed discussion of the anticipated risk 

assessment and data needs. 

Endocrine Disruptor Screening Program: 

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor 

Screening Program (EDSP) 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.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, and or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine related effects caused by the substance, and 

establish a quantitative relationship between the dose and the E, A, or T effect. 

Between October 2009 and February 2010, EPA issued test orders/data call-ins for the first 

group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. 

This list of chemicals was selected based on the potential for human exposure through pathways 

such as food and water, residential activity, and certain post-application agricultural scenarios. 

This list should not be construed as a list of known or likely endocrine disruptors. 

 

1 While the inhalation guideline calls for a 90-day study duration, a 28-day study duration will satisfy the 

Agency’s inhalation exposure data needs.

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Chlorpropham is not among the group of 58 pesticide active ingredients on the initial list to be 

screened under the EDSP. Under FFDCA sec. 408(p) the Agency must screen all pesticide 

chemicals. Accordingly, EPA anticipates issuing future EDSP orders/data call-ins for all 

Registration Review cases, including those for which EPA has already opened a Registration 

Review docket for a pesticide active ingredient. 

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

chemicals, the test guidelines and the Tier 1 screening battery, please visit our website: 

http://www.epa.gov/endo/.

Timeline:

EPA has created the following estimated timeline for the completion of the chlorpropham 

registration review. 

Registration Review for Chlorpropham – Projected Registration Review Timeline

Activities Estimated Date 

Opening the Docket 

Open Docket and Public Comment Period 2010 – December 

Close Public Comment 2011 – February 

Case Development 

Final Work Plan 2011 – May 

Issue DCI 2012 – Jan. – March 

Data Submission 2014 – Jan. – March 

Open Public Comment Period for Draft Risk Assessments 2015 – July – Sept. 

Close Public Comment Period 2015 – Oct. – Dec. 

Registration Review Decision 

Open Public Comment Period for Proposed Registration Review 

Decision 

 2016 – Jan. – March 

Close Public Comment Period 2016 – April – June 

Registration Review Decision and Begin Post-Decision Follow-up 2016 

Total (years) 6 

Guidance for Commenters: 

The public is invited to comment on EPA’s preliminary work plan and rationale. The Agency 

will carefully consider all comments as well as any additional information or data provided in a 

timely manner prior to issuing a final work plan for the chlorpropham case. 

Trade Irritants: 

Through the registration review process, the Agency intends to solicit information on trade 

irritants and, to the extent feasible, take steps toward facilitating irritant resolution. Growers and 

other stakeholders are asked to comment on any trade irritant issues resulting from lack of 

Maximum Residue Limits (MRLs) or disparities between U.S. tolerances and MRLs in key 

export markets, providing as much specificity as possible regarding the nature of the concern. 

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Water Quality: 

Chlorpropham is not identified as a cause of impairment for any water bodies listed as impaired 

under section 303(d) of the Clean Water Act, based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=88

5. In addition, no Total Maximum Daily Loads (TMDL) have been developed for chlorpropham, 

based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_ 

detail?p_pollutant_group_id=885&p_pollutant_group_name=PESTICIDES. More information 

on impaired water bodies and TMDLs can be found at http://www.epa.gov/owow/tmdl/. The 

Agency invites submission of water quality data for this pesticide. To the extent possible, data 

should conform to the quality standards in Appendix A of the OPP Standard Operating 

Procedure: Inclusion of Impaired Water Body and Other Water Quality Data in OPP’s 

Registration Review Risk Assessment and Management Process (see http://www.epa.gov/ 

oppsrrd1/registration_review/water_quality_sop.htm) in order to ensure they can be used 

quantitatively or qualitatively in pesticide risk assessments. 

Environmental Justice: 

EPA seeks to achieve environmental justice, the fair treatment and meaningful involvement of all 

people, regardless of race, color, national origin, or income, in the development, implementation, 

and enforcement of environmental laws, regulations, and policies. To help address potential 

environmental justice issues, the Agency seeks information on any groups or segments of the 

population who, as a result of their location, cultural practices, or other factors, may have 

atypical, unusually high exposure to chlorpropham compared to the general population. Please 

comment if you are aware of any sub-populations that may have atypical, unusually high 

exposure compared to the general population. 

Other Information: 

Stakeholders are also specifically asked to provide information and data that will assist the 

Agency in refining the risk assessments, including any species-specific ecological 

determinations. The Agency is interested in obtaining the following information: 

1. information which may help the Agency calculate how much chlorpropham is released 

into the environment from potato storage facilities where chlorpropham is used 

2. confirmation on the following label information 

a. sites of application 

b. formulations 

c. application methods and equipment 

d. maximum application rates 

e. frequency of application, application intervals, and maximum number of 

applications per season 

f. geographic limitations on use 

3. use or potential use distribution (e.g., acreage and geographical distribution of relevant 

crops) 

4. use history 

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5. median and 90th percentile reported use rates (lbs ai/1000 sq ft) from usage data – 

national, state, and county 

6. application timing (date of first application and application intervals) by crop – national, 

state, and county 

7. sub-county crop location data 

8. usage/use information for non-agricultural uses 

9. directly acquired county-level usage data (not derived from state level data) 

a. maximum reported use rate (lbs ai/acre) from usage data – county 

b. percent crop treated – county 

c. median and 90th percentile number of applications – county 

d. total pounds per year – county 

e. the year the pesticide was last used in the county/sub-county area 

f. the years in which the pesticide was applied in the county/sub-county area 

10. typical application interval (days) 

11. state or local use restrictions 

12. ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian and 

mammalian mortalities) not already reported to the Agency 

13. monitoring data 

Next Steps: 

After the 60-day public comment period closes, the Agency will review and respond to any 

comments received in a timely manner and then issue a Final Work Plan for the registration 

review of chlorpropham. 

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II. FACT SHEET 

 

Background Information: 

• Chlorpropham registration review case number: 0271. 

• Chlorpropham PC code: 018301. 

• Chlorpropham CAS No.: 101-21-3. 

• Chlorpropham was first registered for use in the United States in 1962.

• The RED for Chlorpropham was completed in October 1996 and the TRED for 

Chlorpropham was completed in September 2002.

• The technical registrants for chlorpropham are Aceto Agricultural Chemicals 

Corporation, Decco US Post-Harvest, Inc., and Pin Nip, Division of 1,4 Group, Inc. 

• There are currently thirteen end-use products and three technical products registered for 

chlorpropham. There are also 5 active state-specific Special Local Need (SLN) 

registrations. 

• Tolerances for chlorpropham are established in 40 CFR Part 180.181. 

• Pesticide Re-evaluation Division, Chemical Review Manager: Eric Miederhoff, 

miederhoff.eric@epa.gov. 

• Registration Division contact: Tony Kish, kish.tony@epa.gov.

Use & Usage Information: (For additional details on label rates and use sites, refer to Appendix 

A: Label, Use, and Usage Table in the chlorpropham docket EPA-HQ-OPP-2010-0923.) 

• Based on the percent of the volume treated and total pounds applied, chlorpropham is the 

top active ingredient (a.i.) used as a post-harvest treatment on potatoes (USDA NASS, 

2007). During the 2005-2006 marketing year, 168,100 pounds of chlorpropham were 

applied to potatoes accounting for nearly 50% of the volume treated (USDA NASS, 

2007). This usage covers applications made in off-farm warehouses, shipping and 

processing facilities, and on farms with storage facilities. Chlorpropham was also the 

leader when usage was previously surveyed in 1996. 

• Chlorpropham may be formulated as an emulsifiable concentrate, a liquid ready-to-use, 

and as a solid (for use in aerosol generator/fogger). 

• This chemical is applied as a post-harvest fumigation/non-fumigation treatment for 

potatoes. It may also be used as a broadcast (mist) treatment on ginkgo trees or as a 

directed spray for field grown Easter lilies. 

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Ecological Risk Assessment Status:

Please refer to the Registration Review: Preliminary Problem Formulation for Environmental 

Fate and Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments for 

Chlorpropham, dated November 4, 2010, for the most recent ecological review of chlorpropham. 

Due to the limited amount of outdoor chlorpropham use, the potential for chlorpropham to enter 

the environment had been assumed to be low. Consequently, the Agency had not previously 

conducted an environmental fate and ecological risk assessment for chlorpropham. Rather, a 

summary of the available environmental fate and effects data was prepared in support of the 

1996 RED. 

Additionally, during the evaluation of a waiver request for a number of ecological studies, the 

Agency used surrogate data from two structurally similar chemicals to perform a screening-level 

assessment. This assessment (please refer to Waiver Review on Generic DCI Regarding 

Chlorproham for Use on Easter Lilies and Ginkgo Trees. dated September 20, 2001 for 

additional information) concluded that chlorpropham may impact endangered species of 

freshwater fish and invertebrates. 

 

Exposure Pathways: 

• Based on the limited acceptable environmental fate data, chlorpropham is expected to be 

mobile to moderately mobile in soils. Surface water contamination resulting from the 

outdoor use may be expected to occur predominantly via spray drift and/or from the 

transport in runoff. Vapor pressure data suggest that one route of dissipation for 

chlorpropham will be volatilization.

• The geographically limited SLN Easter lily and gingko tree uses may result in 

chlorpropham deposition into local surface water and subsequent exposure to aquatic 

organisms. Terrestrial organisms may be exposed through dermal uptake/ingestion, root 

uptake, or inhalation.

• The potato storage use may result in atmospheric transport of chlorpropham as a vapor or 

aerosol. Terrestrial organisms may be exposed to chlorpropham through ingestion, root 

uptake, or inhalation.

Summary of Toxicity Data:

• Chlorpropham is classified as: 

 Moderately toxic to freshwater fish and invertebrates on an acute exposure basis. 

 Practically nontoxic to terrestrial birds on an acute oral and subacute dietary 

exposure basis. 

 Practically nontoxic to mammals on an acute oral exposure basis. 

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 Practically nontoxic to honey bees on an acute contact exposure basis. 

• No data are available on the toxicity of chlorpropham to aquatic or terrestrial plants. 

However, chlorpropham is a known herbicide and plant growth regulator and, thus, 

phytotoxic effects are considered likely. 

Human Health Risk Assessment Status: 

Please refer to Chlorpropham. Human-Health Assessment Scoping Document in Support of 

Registration Review, dated November 2, 2010, for a detailed discussion of the key findings of the 

most recent human health risk assessment. A summary follows: 

• Past chlorpropham risk assessments rely in part on data from studies in which adult 

human subjects were intentionally exposed to a pesticide to determine their dermal and 

inhalation exposure. Many such studies, involving exposure to many different pesticides, 

comprise generic pesticide exposure databases such as the Pesticide Handlers Exposure 

Database (PHED) and the Agricultural Reentry Task Force (ARTF) Database. EPA has 

reviewed all the studies supporting these multi-pesticide generic exposure databases, and 

has found no clear and convincing evidence that the conduct of any of them was either 

fundamentally unethical or significantly deficient relative to the ethical standards 

prevailing at the time the research was conducted. All applicable requirements of EPA’s 

Rule for the Protection of Human Subjects of Research (40 CFR Part 26) have been 

satisfied, and there is no regulatory barrier to continued reliance on these studies. 

Hazard Characterization:

• Chlorpropham is a plant growth regulator that works by stopping cell division and plant 

tissue growth. Chlorpropham is classified as a carbanilate herbicide and contains a 

carbamate linkage, but was not found to cause cholinesterase inhibition in a reproduction 

study or in chronic studies in dogs and rats. 

• Chlorpropham has low acute oral and dermal toxicities (Toxicity Category III for oral 

and IV for dermal exposure). Chlorpropham is a mild eye and skin irritant (Toxicity 

Category III and IV, respectively). It is not a dermal sensitizer. 

• Chlorpropham is classified as a Group E chemical (i.e., no evidence of noncarcinogenicity in humans). 

• Chlorpropham has an FQPA Safety Factor of 1x. 

Dietary (Food and Drinking Water):

• The most recent dietary-exposure assessment was performed in conjunction with the 

TRED in 2002. 

• An unrefined acute dietary-risk assessment was conducted for chlorpropham use on 

potatoes using tolerance-level residues and 100% crop treated. Dietary-risk estimates are 

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provided for the population subgroup females 13-50 years old (the only population 

requiring an acute assessment). This assessment concluded that the acute risk estimate is 

below the Agency’s level of concern (<100% acute population-adjusted dose (aPAD)) at 

the 95th exposure percentile (4% of the aPAD) for females 13-50 years old. 

• A partially refined chronic dietary exposure assessment was performed using PDP 

monitoring data for potatoes and milk and anticipated residues derived from feeding 

studies for other livestock commodities. This assessment concluded that for all 

commodities, the chronic risk estimates are below the Agency’s level of concern (<100% 

chronic population-adjusted dose (cPAD)) for the general U.S. population (4% of the 

cPAD) and all population subgroups. The chronic dietary exposure estimate for the 

highest exposed population subgroup, children 1-6 years old, is 10% of the cPAD. 

• The only chlorpropham use that may result in exposure through drinking water is 

application to Easter lilies. The Agency assessed potential exposure to water based on 

the Easter lily use which is limited to Curry County, Oregon and Del Norte County, 

California. Approximately 150 acres (1/4 square mile) receives treatment with 

chlorpropham annually. Any potential exposure would be limited to these two counties. 

Please refer to the 2002 chlorpropham TRED for more information on the drinking water 

assessment. 

 Surface water intakes are not located near lily bulb cultivating areas; therefore, the 

potential for exposure to chlorpropham in surface water sources of drinking water is 

negligible. The Agency concluded that no population groups are exposed to 

chlorpropham residues in surface water sources of drinking water at a level that 

poses an acute or chronic risk concern. 

 For acute risk from ground water sources of drinking water, potential exposure to 

chlorpropham from drinking water is not of concern. 

 For chronic risk from ground water sources of drinking water, the Easter lily use is 

not of concern. 

 For carcinogenic risk, potential chronic exposure to chlorpropham from ground 

water sources of drinking water associated with the Easter lily bulb use is estimated 

to range from 2.0 ppb to 8.0 ppb. This range is based on varying modeling 

parameters including degradation half life and assuming 100% of the parent 

chlorpropham is degraded to 3-chloroanaline. As such, these estimates may not be 

suitable for a cancer assessment and will overestimate cancer risk. The 

conservative nature of the risk estimates, combined with the limited use area, gave 

the Agency reasonable assurance that aggregate cancer risks are not of concern. 

Residential (Non-occupational):

 

• As there are no registered uses at residential sites, residential handler and post-application 

assessments were not conducted in the most recent risk assessment. 

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Occupational: 

• The most recent occupational exposure assessment was completed in 1995 in support of 

the chlorpropham RED. 

• The 1995 assessment included the potential for exposure to handlers resulting from the 

chlorpropham Section 24(c) use on Easter lilies. However, these handler assessments did 

not include estimates of inhalation exposure. Also, handler exposure has not been 

previously assessed for airblast application to ginkgo trees. 

The post-harvest application of chlorpropham on potatoes can be done using either 

automated sprayers or a forced air distribution method. Exposure data were not available 

for the automated sprayer application on potatoes. Additionally, it was assumed that the 

forced air distribution method was a closed automated system; therefore, a handler 

assessment on this use was not warranted. 

Provided that commercial pesticide handlers use label-required personal protective 

equipment (PPE), all assessed margins of exposure (MOEs) were not of concern. 

• Occupational post-application exposure was not assessed previously. 

Cumulative: 

• Although chlorpropham is a carbanilate herbicide and contains a carbamate linkage, it 

was not included in the carbamate cumulative risk assessment because it is not an Nmethyl carbamate. Chlorpropham does not inhibit cholinesterase and, thus, does not 

share a common mechanism of toxicity with the N-methyl carbamate assessment group.

Incidents: 

• The Agency consulted the Ecological Incident Information System and the Avian 

Incident Monitoring System databases for reports of ecological incidents. Neither 

database reported any incidents involving chloropropham. 

• The Agency consulted the OPP Incident Data System (IDS), the Centers for Disease 

Control and Prevention/National Institute for Occupational Safety and Health 

(CDC/NIOSH), Sentinel Event Notification System for Occupational Risk-Pesticides 

(SENSOR) and the Agricultural Health Study databases for human health incidents 

involving chlropropham. From 1998 to 2007, the NIOSH SENSOR database identifies 

seven cases that reportedly involve the active ingredient chlorpropham. The health 

effects reported include: gastrointestinal (75%), respiratory (50%), ocular (25%), 

neurological (25%), and dermal (25%). Symptoms are not mutually exclusive; a patient 

may have many symptoms. These cases are classified as low to moderate severity (three 

as low, one as moderate). Two cases (one occupational and one nonoccupational) were 

the result of drift exposure. One case involved a landscaper experiencing dermal 

symptoms while applying chlorpropham. One case involved exposure to the applicator 

while spraying greenhouse ornamentals.

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Tolerances and International Harmonization: 

• The U.S., Mexican, Canadian, and Codex residue definitions for plant commodities are 

harmonized. For potatoes, the U.S. tolerance and Codex maximum residue limits 

(MRLs) are harmonized; however, the U.S. tolerance level and the Canadian MRL for 

residues in/on potato are not harmonized (U.S.: 30 ppm vs. Canadian: 15 ppm). Only 

the U.S. has a tolerance established for residues in/on potato processed products (wet 

peel). For livestock commodities, the Codex tolerance expression is not harmonized and 

the MRLs are set at different levels for cattle meat, byproducts, and milk (i.e., U.S. meat: 

0.06 ppm vs. Codex MRLs cover cattle commodities and are established for residues in 

fat and kidney, while U.S. tolerances cover commodities from cattle, goats, hogs, horses, 

and sheep). Canadian MRLs are not established for residues in livestock commodities 

and are therefore not harmonized. 

Data Call-In Status: 

• Generic data call-ins (GDCI-018301-17113, GDCI-018301-17712, and GDCI-018301-

17906) were issued in April 1994, December 1996, and December 2003, respectively, to 

provide data for the 1996 Chlorpropham RED and the 2002 TRED. Analytical method 

data from Guideline Nos. 171-4d and 171-4j are overdue and remain outstanding from 

GDCI-018301-17113. All data requirements from subsequent data call-ins for 

chlropropham have been fulfilled. 

Labels: 

 

• Labels can be obtained from the Pesticide Product Label System (PPLS) website: 

http://oaspub.epa.gov/pestlabl/ppls.home. 

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III. Summary of Data Gaps – Chlorpropham 

The table below summarizes all anticipated and previously required data for 

chlorpropham in Section I of this document (Preliminary Work Plan), the Registration Review: 

Preliminary Problem Formulation for Environmental Fate and Ecological Risk, Endangered 

Species, and Drinking Water Exposure Assessments for Chlorpropham, dated November 4, 

2010, and the Chlorpropham. Human-Health Assessment Scoping Document in Support of 

Registration Review dated November 2, 2010. 

Guideline 

Number Data Needs Test 

Material 

Estimated 

Timeframe 

ANTICIPATED REGISTRATION REVIEW DCI STUDIES 

870.3465 90-Day Inhalation Toxicity1 TGAI 24 

870.6200 Acute and Subchronic Neurotoxicity TGAI 24 

870.7800 Immunotoxicity TGAI 12 

835.1230 Sediment and soil absorption/desorption for parent and 

degradates TGAI 12 

835.1240 Soil Column Leaching TGAI 12 

835.4100 Aerobic Soil Metabolism TGAI 24 

850.2100 Avian Acute Oral Toxicity, passerine TGAI 12 

850.4100 Terrestrial Plant Toxicity, Tier II (seeding emergence)2 TGAI 12 

850.4150 Terrestrial Plant Toxicity, Tier II (vegetative vigor)2 TGAI 12 

850.4400 Aquatic Plant Toxicity, Tier 22 TGAI 12 

850.5400 Algal Toxicity, Tier 22 TGAI 12 

850.2300 Avian Reproduction TGAI 24 

850.1300 Daphnid Chronic Toxicity TGAI 12 

850.1400 Fish Early-Life Stage Toxicity, freshwater TGAI 12 

 OUTSTANDING DATA FROM GDCI-018301-17113 

171-4d Res. analyt. method - animal 12 

171-4j Mag. Meat/milk/poultry/egg 18 

 

1 While the inhalation guideline calls for a 90-day study duration, a 28-day study duration will satisfy the 

Agency’s inhalation exposure data needs.

2 The Agency anticipates requiring a Tier II study. The anticipated Data Call-In Notice will note that a 

Tier I study may be conducted in lieu of a Tier II study with the understanding that adverse effects (even 

if <25%) would necessitate a Tier II study as well. The purpose of a Tier II study is to establish either a 

No Observed Adverse Effect Concentration (NOAEC) or a concentration at which there is a 5% observed 

effect (EC05) to be used in an endangered species risk assessment for nontarget plants. If neither an 

NOAEC nor an EC05 value is available, then the Agency may have to presume that chlorpropham “may 

affect” listed nontarget plant species in the registration review endangered species risk assessment.