UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES

**CERTIFIED MAIL**

Dear Registrant:
This is to inform you that the Environmental Protection Agency (hereafter referred to as EPA or the Agency) has completed its “Report of FQPA Tolerance Reassessment Progress and Interim Risk Management Decision (TRED) for chlorpropham”. A Notice of Availability, allowing public comment for a 30-day period, will be published in the Federal Register (FR) shortly. This TRED, which was approved on July 19, 2002, contains the Agency’s decision on chlorpropham.
The Federal Food, Drug and Cosmetic Act (FFDCA), as amended, requires EPA to reassess all the tolerances for registered chemicals in effect on or before the date of the enactment of the Food Quality Protection Act (FQPA) in August of 1996 against the new safety standard adopted in the FQPA. In reassessing 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 a modification or revocation occurs. A reregistration eligibility decision (RED) for chlorpropham, was finalized and signed on August 1, 1996, prior to FQPA enactment

**.** Therefore, it needed to be updated to reassess the tolerances under the FQPA standard.
The Agency has evaluated the dietary risk associated with chlorpropham and has determined that provided the Special Local Need registration (SLN) for Easter lily bulb use is amended to reduce the maximum rate of application from 3.99 lb a.i./A to 2.0 lb a.i./A as agreed upon by stakeholders, there is a reasonable certainty that no harm to any population subgroup will result from aggregate exposure to chlorpropham when considering dietary exposure and all other non-occupational sources of pesticide exposure for which there is reliable information. Therefore, with this mitigation measure in place, 15 tolerances are now considered reassessed and 9 new tolerances are will be established for residues of chlorpropham in/on raw agricultural commodities under section 408(q) of the FFDCA.FQPA requires that EPA consider “available information” concerning the cumulative effects of a

particular pesticide’s residues and “other substances that have a common mechanism of toxicity.” The reason for consideration of other substances is due to the possibility that low-level exposures to multiple chemical substances that cause a common toxic effect by a common mechanism could lead to the same adverse health effect, as would a higher level of exposure to any of the other substances individually. EPA did not perform a cumulative risk assessment as part of this reregistration review of chlorpropham, because the Agency has not determined if there are any other chemical substances that have a mechanism of toxicity common with that of chlorpropham. If EPA identifies other substances that share a common mechanism of toxicity with chlorpropham, then a cumulative risk assessment will be conducted that includes chlorpropham. Further, EPA is in the process of developing criteria for characterizing and testing endocrine disrupting chemicals and plans to implement an Endocrine Disruptor Screening Program. Chlorpropham will be reevaluated at that time and additional studies may be required.
The Agency’s human health findings for the pesticide chlorpropham, were discussed in a closure conference call, and are summarized in the enclosed chemical overview of the risk assessments. These risk assessments and other documents pertaining to the chlorpropham tolerance reassessment decision are listed at the end of this document (Attachment 1) and are available on the Internet at http://www.epa.gov/pesticides/reregistration/status.htm and in the public docket for viewing.
Tolerances are established for residues of chlorpropham in/on raw agricultural commodities as defined in 40 CFR §180.181. The current tolerance in or on potatoes is currently expressed in terms of the combined residues of chlorpropham and its 1-hydroxy-2-propyl-3'-chlorocarbanilate metabolite and is established at 50 parts per million (ppm). The tolerance for potatoes should be reduced to 30 ppm, and be expressed in terms of chlorpropham alone (chlorpropham per se ). Additionally, a tolerance for residues of chlorpropham on potatoes, wet peel, should be established at 40 ppm.
Interim tolerances have been established for residues of chlorpropham in/on plant and animal commodities in 40 CFR §180.319. The Agency will propose to reassess thirteen interim tolerances including milk, meat, fat, and meat byproducts of cattle, hog, horse, and sheep, based on results of the ruminant feeding study, and will propose to revoke one interim tolerance (spinach) for failure to provide additional data required to support reregistration. Tolerances will be raised or established to express combined residues of chlorpropham and 4-HSA (4-hydroxychlorpropham-O-sulfonic acid) for the meat and meat byproducts of cattle, horse, sheep, goat, and hog at 0.06 ppm (except kidney), 0.30 ppm for kidney and milk, and 0.20 ppm for fat (a total of 21 tolerances). A total of 24 tolerances will be raised, established, or revoked by the TRED for chlorpropham when the tolerances for post-harvest and wet peel potato are included, and the revocation for spinach occurs.
The Codex Commission has not established or proposed maximum residue limits (MRLs) for residues of chlorpropham in/on various raw agricultural and processed commodities. Therefore, there are no inconsistencies with respect to compatibility of U.S. tolerances with Codex MRLs. The following table summarizes EPA’s tolerance reassessment decision.**Table 1. Tolerance Reassessment Summary for Chlorpropham**

**Commodity Current** 

**Tolerance (ppm)**  **Tolerance**

**Reassessment (ppm)**  **Comment/Correct Commodity Definition**

**Current and Proposed Tolerances Under 40 CFR § 180.181**

**for chlorpropham per se**  Potato (Post-Harvest) 50 30 Tolerance lowered based on results of a magnitude of residue study in potatoes for chlorpropham per se. Currently listed under 40 CFR § 180.181 as combined residues of chlorpropham and its 1-hydroxy-2-propyl-3'- chlorocarbanilate metabolite. Potato, wet peel none 40 Tolerance to be established based on field trial and commercialscale processed potato waste studies. This tolerance is based on the Highest Average Field Trial (HAFT), the maximum expected residue in potato, wet peel, at 36 ppm , and the average concentration factor (3x) from a commercial-scale processed potato waste study. **Interim Tolerances Currently Listed Under 40 CFR § 180.319 for chlorpropham**  **per se and Proposed Reassessed Tolerances**  Cattle, meat 0.05 0.06

Tolerance raised (or established) based on results of a ruminant feeding study and calculated Maximum Theoretical Dietary Burden (MTDB) estimates. The current tolerance should be recodified under 40 CFR §180.181(a) (1) to be expressed for combined residues of chlorpropham and 4- hydroxychlorpropham-O-sulfonic acid (4-HSA). Cattle, fat 0.05 0.20 Cattle, kidney none 0.30 Cattle, meat byproduct 1 0.05 0.06

Hog, meat 0.05 0.06 Hog, fat 0.05 0.20 Hog, Kidney none 0.30 Hog, meat byproducts 1 0.05 0.06

Goat, meat none 0.06 Goat, fat none 0.20 Goat, kidney none 0.30 Goat, meat byproducts 1 none 0.06

Horse, meat 0.05 0.06 Horse, fat 0.05 0.20 Horse, kidney none 0.30 Horse, meat byproducts 1 0.05 0.06

Milk 0.05 0.30**Commodity Current**  **Tolerance (ppm)**  **Tolerance**

**Reassessment (ppm)**  **Comment/Correct Commodity Definition**

Sheep, meat 0.05 0.06 Tolerance raised (or established) based on results of a ruminant feeding study and calculated Maximum Theoretical Dietary Burden (MTDB) estimates. The current tolerance should be recodified under 40 CFR §180.181(a) (1) to be expressed for combined residues of chlorpropham and 4- hydroxychlorpropham-O-sulfonic acid (4-HSA). Sheep, fat 0.05 0.20 Sheep, kidney none 0.30 Sheep, meat byproducts 1 0.05 0.06

Spinach 0.3 Revoke The interim tolerance was based on insufficient data; proposed revocation is based on failure to provide additional data required to support tolerance reassessment
1 Revised Commodity Definition: (except kidney) **Labeling For End-Use Products**
In completing this TRED, the Agency has identified certain label amendments which should be implemented. A tabular summary of label amendments, listed below, describes how label language should be amended. The implementation of these amendments will ensure that the reassessed tolerances are adequate for the maximum label rates, and will also ensure consistency among the labels.
In order to be eligible for reregistration, registrants supporting chlorpropham registrations must submit label applications for amended registration. This application should include the following items: a completed EPA application form 8570-1, five copies of the draft label with all label amendments outlined in Table 2 of this document incorporated, and a description on the application, such as, “Responding to TRED Document”. All amended labels need to be submitted within 8 months of signature of this document to the Registration Division (RD). The RD contact is Cynthia Giles-Parker at (703) 305-7740.**Table 2. Amendments to CIPC Labels based on Formulation Class Formulation Class**  **Recommended Label Amendments** Aerosol Ready To Use (RTU) Products The product labels currently state that “if potatoes are held in storage longer than originally anticipated, the potatoes may be retreated.” The labels should clearly state a total seasonal rate of 0.028 lb ai/1000 lbs potatoes, not to exceed 165% of the typical (0.017lb ai/1000lbs of potatoes) rate. In the case of labels specifying 145% of the typical rate, the total seasonal rate should not exceed 0.025lbs ai/1000lbs of potatoes. For all products heated above 250 E F, including CIPC Briquette Aerosol (EPA Reg. Number 2749-520), and Pin Nip 98.6% Aerosol (EPA Reg. Number 65726-3) For entry into the enclosed treatment/storage area anytime after application until ventilation requirements listed on this labeling have been completed, in addition to PPE (long-sleeved shirt and long pants; shoes plus socks; chemical resistant gloves such as ormade of any waterproof material); handlers must wear a respirator with an organicvapor removing cartridge with a prefilter approved for pesticides (MSHA/NIOSH approval number prefix TC-23C), or a canister approved for pesticides (MSHA/NIOSH approval number prefix TC-14G), or a NIOSH-approved respirator with an organic vapor (OV) cartridge or canister with any R, P prefilter Emulsifiable Concentrate (EC) Label should be amended to reduce the maximum rate of application from 3.99 lb a.i. to 2.0 lb a.i. per acre for Easter lily use For potatoes, a maximum seasonal rate (0.0104 lb ai/1000lbs potatoes) should be specified.

**Additional Generic Data Requirements**
Additional generic confirmatory data are required concerning UV/Visible Absorption (OPPTS 830.7050) for technical registrants of chlorpropham.
The Agency is also requesting a special residue study (under crop field trial guideline study, OPPTS 860.1500) to determine the potential for thermal degradates to form during aerosol application as a result of thermal degradation to deposit as residues in or on stored potatoes. The study is required because the Agency cannot determine whether or not the chlorophenyl isocyanate, or other thermal degradates, are produced during aerosol treatment based on the literature citations and the submitted plant metabolism study alone. The study should include the range of temperatures typically used by the aerosol generators, at what temperature the decomposition products are formed during the process and the presence and amount of any isocyanates; (in particular, chlorophenyl isoncyanate), as well as the potential intermediary 5-chloro-2-benzoxazolinone.
Note that Technical registrants will be sent a Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Section 3(c)(2)(B) Data-Call-In (DCI) letter in a separate mailing. Ifyou have questions on this document, please contact the Chemical Review Manager, Gary Mullins, at

(703) 308-8044.
Sincerely,

Lois A. Rossi, Director Special Review and Reregistration Division

2 Enclosures: Chlorpropham Summary and Overview**ATTACHMENT 1**

**Supporting Documents Considered for the Chlorpropham Tolerance Reassessment Decision**

1. Danette Drew (USEPA\OPPTS\OPP\HED).Chlorpropham (CIPC) (018301). HED’s Revised Human Health Risk Assessment Chapter for the Tolerance Reassessment Eligibility Decision. July 10, 2002.

2. Danette Drew (USEPA\OPPTS\OPP\HED).Chlorpropham (CIPC) (018301).Revised Product Chemistry and Residue Chemistry Chapter for the Tolerance Reassessment Eligibility Decision (TRED). June 10, 2002.

3. Danette Drew (USEPA\OPPTS\OPP\HED). Chlorpropham (CIPC) (018301).Acute, Chronic and Cancer Anticipated Residues and Dietary Exposure Assessments for the Tolerance Reassessment Eligibility Decision. February 25, 2002.

4. William B. Greear (USEPA\OPPTS\OPP\HED).Chlorpropham - Reregistration Case No. 0271 - Toxicology Chapter for the Reregistration Eligibility Decision Document on Chlorpropham. January 13, 1999.

5. Brenda Tarplee (USEPA\OPPTS\OPP\HED).Report of the FQPA Safety Factor Committee. December 17, 1998.

6. Dirk F. Young, Ph.D., (USEPA\OPPTS\OPP\EFED). Revised FQPA Drinking Water Assessment for Chlorpropham. June 3, 2002.

7. Danette Drew, (USEPA\OPPTS\OPP\HED). Response to Registrant’s Letter Regarding Label Amendments. November 20, 2001.

8. David G. Anderson, Ph.D., (USEPA\OPPTS\OPP\HED). Carcinogenicity Peer Review of Chlorpropham October 11, 1994.

9. Danette Drew, (USEPA\OPPTS\OPP\HED). Response to CIPC Task Force Comments on the Human Health Risk Assessment for the TRED. March 27, 2002

10. Danette Drew, (USEPA\OPPTS\OPP\HED). Agency’s Response to Pin Nip April 08, 2002 Comments on the Human Health Risk Assessment for the Tolerance Reassessment Eligibility Decision (TRED). April 11, 2002

11. Lori L. Brunsman (USEPA\OPPTS\OPP\HED). Para-Chloroaniline Hydrochloride (Diflubenzuron, Dimilin), (017203), Quantitative Risk Assessment (Q 1 *) Based on B6C3F 1 Mouse Gavage Study With mg/kg Body Weight 3/4/Day Unterspecies Scaling Factor. June 14, 2001.12. William B. Greear (USEPA\OPPTS\OPP\HED). Chlorpropham - Report of the Hazard

Identification Review Committee. October 16, 1998.
These risk assessments and other documents pertaining to the chlorpropham tolerance reassessment decision are available on the Internet at http://www.epa.gov/pesticides/reregistration/status.htm , and in the public docket for viewing.

## OVERVIEW OF CHLORPROPHAM **RISK ASSESSMENT**

**Introduction**

This document summarizes EPA’s human health and drinking water risk findings and conclusions for the herbicidal carbamate pesticide chlorpropham, as presented fully in the documents, "Chlorpropham HED Revised Human Health Risk Assessment Chapter for the Tolerance Reassessment Eligibility Decision, June 7, 2002" and “Revised FQPA Drinking Water Assessment for Chlorpropham, June 5, 2002”. The purpose of this overview is to assist the reader by identifying the key features and findings of these risk assessments. This overview was developed in response to comments and requests from the public, which indicated that the risk assessments were difficult to understand, that they were too lengthy, and that it was not easy to compare the assessments for different chemicals due to the use of different formats.
The chlorpropham risk assessment, and additional supporting documents, are posted on EPA’s Internet website (http://www.epa.gov/pesticid es/chlorpropham.html) and are available in the Pesticide Docket for public viewing. The av ailability of the Agen cy’s report on the FQPA Tolerance Reassessment Decision (TRED) for chlorpropham will be announced in a Federal Register Notice. Prior to publication of the No tice, the Agency conducted a closure conference call to describe the regulatory decisions to stakeholders.
The Federal Food, Drug, and Cosmetic Act (FFDCA), as amended by the Food Quality Protection Act (FQPA) of 1996, require s EPA to review all the tolerances for registered chemicals in effect on or before the date of the enactment of FQPA. In reviewing th ese tolerances, the Agency must consider, among other things, aggregate risks from non-occupational sources of pesticide exposure, whether there is increas ed susceptibility to infants and ch ildren, 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 a revocation occurs. A reregistration eligibility decision (RED) for chlorpropham was finalized and signed on A ugust 1, 1996, prior to FQPAenactment; therefore, tolerances needed to be reassessed to reflect the provisions of FQPA.

Risks summarized in this document are those th at result only from the use of chlorpropham. The FQPA requires that the Agency consider “available information” concerning the cumulative effects of a particular pesticide’s residues and “o ther substances that have a common mechanism of toxicity”. The reason for consideration of other s ubstances is due to the possibility that low-level exposures to multiple chemical substances that cause a common toxic effect by a common mechanism could lead to the same adverse health effect as would a higher level of exposure to any of the other substances individually. The Agency did not perform a cumulative risk assessment as part of this tolerance reassessment of chlorp ropham because the Agency has determined that chlorpropham does not share a common mechanism of toxicity with other cholinesterase-inhibiting methyl-carbamates.2 

### Use Profile

**Herbicide:** registered for use on the following crops/s ites: sprout control on post-harvest stored potatoes. There are four Special Local Needs [24(c) ] registrations. They are for use on Easter lilies (on approximately 150 acres annually in Oregon and California), on gingko trees in Washington, DC, and on post-harvest stored potatoes growing in high humidity conditions in the state of Maine which requires a higher application rate.

**Formulations:** registered formulations include a technical grade (from 98%, to 99% active ingredient (a.i.)), aerosol ready-to-use (RTU ) (from 46.5 to 98.7% a.i.), and liquid emulsifiable concentrate (EC), (from 23.8 to 36% a.i.). The re gistrant of an additional RTU product (formulated at 49.65% a.i.) has requested a voluntary cancellation of this product.
**Methods of Application:** may be applied by direct spray, lo w volume direct spray (concentrate), high pressure spray (dilute), stored commodity fumigation, and stored commodity non-fumigation (aerosol).
**Application Rate:** chlorpropham application rates to post-harvest potatoes vary, and depend on method of application, length of storage, and stor age temperature. Rates of application to postharvest potatoes destined for processing range fr om a maximum total application rate of 1.65 lb a.i./600 hundred weight (cwt) to 1.65 lb a.i./400 cwt. Post-harvest stored potatoes destined for fresh markets may receive a maximum total application rate of 1.45 lb a.i./600 cwt. Current labels do not restrict or limit the number of applications to st ored potatoes, as long as the maximum application rate is not exceeded. A total of approximately 300 lbs of chlorpropham a.i is used annually on gingko trees in Washington, DC, at an application rate of 0.02 lbs a.i./gallon. The maximum total application rate for the Easter lily bulb use is 3.99 lb a.i./A.
**Application Timing:** chlorpropham may be applied pre-bloom (for Easter lilies and gingko trees), and as a dormant application to post-harvest potatoe s in storage. Post-harvest potatoes are the only food/feed use.
**Annual Poundage:** the best available data for total annual amount of chlorpropham active ingredient (a.i.) used is from a USDA National Agricultural Statistics Service (NASS) publication for 1996. Total annual chlorpropham used was approximately 445,600 pounds.
**Registrants:** Aceto Agriculture Chemicals Corporation, Cerexagri, Inc., and Pin/Nip Inc.3 

### Human Health Risk Assessment
**Acute Dietary (Food) Risk**
Acute dietary risk from food is calculated by considering what is eaten in one day. A risk estimate that is less than 100% of the acute Popul ation Adjusted Dose (aPAD) (the dose at which an individual could be exposed on any given day and no adverse health effects would be expected) is not of concern to the Agen cy. The aPAD is the reference dose (RfD) adjusted for the FQPA Safety Factor.
The Agency performed a conservative determin istic (Tier 1) analysis (which assumed tolerance level residues based on existing and/or reassessed tolerances and 100 % crop treated (CT). The acute dietary exposure analysis is based on the Dietary Exposure Evaluation Model (DEEMTM). One day consumption data from USDA’s Continui ng Surveys of Food Intake by Individuals (CSFII 1989-92) are used on an individual-by-individual basis for acute exposure assessment.
• Acute dietary (food) risk is not of concern (4.0% of the aPAD) at the 95 thexposure percentile for females 13-50 years old (the only subgroup requiring an acute assessment).
• An acute endpoint for the general population, including infants and children, was not available from the toxicity studies, including the developmental toxicity studies. The maternal toxicity in these studies was not attributable to a single exposure. Therefore, no toxicity endpoint or dose was selected fo r the general population including infants and children.
• The toxicity endpoint for the acute dietary assessment is increased resorption and postimplantation loss based on a developmental toxicity study in rabbits (NOAEL = 250 mg/kg/day). These effects were observed at 500 mg/kg/day (LOAEL).
• The uncertainty factor is 100x, 10x for intr aspecies variability and 10x for interspecies extrapolation.
• The FQPA Safety Factor was reduced to 1X for acute and chronic exposures because: 1) the toxicology data base is complete; 2) there is no indication of increased susceptibility of rats or rabbit fetuses to in utero and/or postnatal exposure in the developmental and reproductive toxicity studies; 3) a developmental neurotoxi city study is not required; 4) dietary (food) exposure estimates are partially refined resulting in a more realistic estimate of dietary exposure; 5) quantifiable contamination of surface or ground water is not likely to result from this use; and 6) there are currently no registered residential uses of chlorpropham, therefore, this type of exposure to infants and children is not expected.
• The acute RfD (aRfD) is 2.5 mg/kg/day. Becau se the FQPA Safety Factor was reduced to4 1X, the aPAD is equal to the aRfD.
• There is no evidence of endocrine disruption from exposure to chlorpropham.
**Chronic Dietary (Food) Risk**
Chronic dietary risk from food is calculated by using the average consumption values for food and average residue values for those foods over a lifetime. Chronic dietary exposure that is less than 100% of the chronic Population Adjusted Do se (cPAD) does not exceed the Agency’s level of concern. The cPAD is the chronic reference dose (cRfD) adjusted for the FQPA Safety Factor.
Residues of chlorpropham per se from USDA Pesticide Data Program (PDP) monitoring data, calculated as point estimates, were used for potatoes in the chronic dietary assessment. Anticipated residues of parent chlorpropham and the 4-HSA metabolite in livestock tissues were derived from the ruminant feeding studies and were used as point estimates in the assessment. Total residues of chlorpropham and the metabolite 4-HSA in milk were calculated by determining the ratio of residues of parent to metabolite in milk fr om the feeding study and applied to the amount of parent reported in milk in the PDP monitoring data.
• Chronic dietary risk estimates for food are below the Agency’s level of concern (<100% cPAD) for the general U.S. population (4% of the cPAD) and all population subgroups. The chronic dietary exposure estimate for highe st exposed population subgroup, children 1-6 years old, is 10% of the cPAD.
• The toxicity endpoint for the chronic dietary ri sk assessment is thyroid toxicity, based on the results of a 2-year feeding study in dogs , where increased thyroid weights and histopathological changes in the thyroid were observed (NOAEL=5 mg/kg/day)

. These effects were observed at 50 mg/kg/day (LOAEL).
• The uncertainty factor is 100x; 10x for intraspecies variability and 10x for interspecies extrapolation.
• The chronic RfD (cRfD) is 0.05 mg/kg/day. As noted in the Ac ute Dietary Risk section, the FQPA Safety Factor was reduced to 1x.
**Cancer Dietary (food) Risk**
The Agency has classified parent chlorpropham as a “Group E” human carcinogen (no evidence of carcinogenicity). However, some ch lorpropham is metabolized to 3-chloroaniline (3- CA) in potatoes and some anilines are known carci nogens. The Agency does not have data on 3-CA necessary to conduct a carcinogenicity risk assessment. However, data are available for 4-chloroaniline (4-CA) which is structurally similar to 3-CA and has a cancer potency factor (Q 1 *) of 1.12 x 10 -1 (mg/kg/day) -1 . This Q 1 * was used as a surrogate to assess the potential cancer risk from 3-CA. However, the use of the 4-CA carci nogenic potency is expected to overestimate risk.5 • In livestock metabolism studies, 3-CA was not detected in milk, meat, kidney or fat. 3-CA was detected in liver. Although no 3-CA was detected in milk, a cancer dietary exposure assessment was performed using 1⁄2 LOD (limit of detection) for milk as well as the 3-CA residue found in liver and potatoes. This exposure scenario reflects a conservative assumption that finite residues may be expected in milk and liver consumed by individuals living in a “local milkshed” where cattle may be fed processed potato waste from nearby potato processing plants. The cancer dietary risk estimate for the general population is 3.4 x 10 -6 , based on this conservative “local milkshed” scenario.
• A second cancer dietary exposur e assessment was performed usi ng estimated potato residues only and omitting milk and cattle liver. This assessment reflects an exposure scenario that assumes no potato waste containing chlorpropham is fed to livestock. This typical scenario is more realistic than the local milkshed s cenario since residues of 3-CA are not expected in milk and only a small amount of the population can be assumed to live in an area where local potato waste may be fed to livestock. The cancer dietary risk estimate for the typical scenario is 2.2 x 10 -6

. The Agency’s level of concern for lifetime cancer risk is generally 1.0 x 10 -6 . However, for chlorpropham, several factors are expected to contribute to overestimating risk including use of the surrogate Q 1 *, the 10-fold range between the NOAEL and LOAEL derived from the 2 year dog feeding study, and the conservatism associated with th e use of anticipated resi dues. Therefore, the Agency does not consider the dietary cancer risk estimate from chlorpropham use to be of concern.
**Drinking Water Dietary Risk**
Drinking water exposure to pesticides can occur through surface and/or ground water contamination. EPA considers acute (one day) a nd chronic (lifetime) drinking water risks and uses either modeling or actual monitoring data, if availa ble, to estimate those risks. To determine the maximum allowable contribution from water allowe d in the diet, EPA looks at how much of the overall allowable risk is contributed by food, thencalculates a “drinking water level of comparison” (DWLOC) to determine whether modeled or monitoring levels exceed this level.
The Agency uses a DWLOC as a surrogate to capture risk associated with exposure from pesticides in drinking water. The DWLOCs repr esent the maximum contribution to the human diet that may be attributed to residues of a pes ticide in drinking water after dietary exposure is considered. Risks from drinking water are asse ssed by comparing the DWLOCs to the estimated environmental concentrations (EECs) in surface and/or ground water. When the EECs are less than the DWLOCs, the Agency is not concerned with drinking water risks.

As previously noted, annual outdoor use of chlorpropham is limited to 300 lbs a.i. each on Easter lilies and gingko trees. However, accurate assessment of the drinking water contamination potential posed by these limited outdoor uses of chlorpropham and its 3-chloroaniline metabolite, is hampered by the near complete lack of envi ronmental fate data for both compounds. Therefore, the Agency is relying on modeling to estimate drinking water dietary risks and on monitoring data for other pesticides used in the lily bulb growi ng region along with fate parameters from surrogate6 chemicals to characterize exposures.
Gingko Tree Use – Surface and Ground Water
Chlorpropham is applied to gingko trees in Wash ington, DC by mist blower to “near dripping point” at an application rate of 0.02 lbs a.i./gallon. There are no drinking water intakes on the Potomac River downstream of Washington, DC, so there is no potential for exposure to chlorpropham through drinking water. Therefore, neither surface water or ground water sources of drinking water are of concern as a result of the gingko tree use.

Easter Lilies – Surface Water
The only chlorpropham use that may result in exposure through drinking water is application to Easter lilies. The Agency assessed potential e xposure 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 chlorp ropham annually. Any pot ential exposure would be limited to these two counties. Surface water intake s are not located near lily bulb cultivating areas, therefore, the potential for exposure to CIPC/3-CA in surface water sources of drinking water is negligible. The Agency concludes that no population group is exposed to chlorpropham residues in surface water sources of drinking water at a level that poses an acute or chronic risk concern.

Easter Lilies – Ground Water
Estimated drinking water concentrations for ground water are based on the SCI-GROW model. The model is a conservative, Tier I assessment that provides a reasonable estimate of exposure in hydrologic environments similar to thos e in which lily bulbs are grown. However, the modeled EEC is a conservative estimate of lifetime exposure and does have considerable uncertainty because of the lack of environmental fate data.
• For acute risk, potential exposure to chlorpropham from drinking water is not of concern. The acute ground water EEC for chlorpropham of 100 ppb does not exceed the DWLOC (72,000 ppb).
• For chronic risk, the Easter lily use is not of concern. The modeled EEC is 100 ppb which does not exceed the 450 ppb DWLOC for kids 1- 6 years (the most sensitive subpopulation).
• 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.

**Residential Risk**7 There are currently no registered residential uses of chlorpropham. Therefore, there is no expected exposure of homeowners to chlorpropham and aggregation with dietary sources of exposure is not necessary.
**Aggregate Risk**
The aggregate risk assessment considers exposure through food, drinking water, and nonoccupational uses (i.e., residential use). Since there are no chlorpropham residential uses, the aggregate assessment examines the combined exposure through food and drinking water only.
• Acute aggregate risk estimates from exposure to chlorpropham in food and water do not exceed the Agency’s level of concern. Th e modeled groundwater EEC does not exceed the acute DWLOC for females 13-50 years old nor is there potential acute exposure to chlorpropham from surface water sources that exceed the Agency’s level of concern.
• Chronic aggregate risk estimates from expos ure to chlorpropham in food and water do not exceed the Agency’s level of concern. Th e modeled groundwater EEC does not exceed the chronic DWLOC for the US population and a ll population subgroups nor is there potential chronic exposure to chlorpropham from surface water sources that exceed the Agency’s level of concern.
**Aggregate Cancer Risk**
The carcinogenic risk estimate (2.2x10 -6 ) for dietary (food) exposure based on the typical use scenario fills the “risk cup”. The only potential drinking water concern is for ground water associated with the use on Easter lilies in Oregon and California (surface water is not of concern for any use). However, the cancer risk assessment is based on a surrogate Q 1 * which is likely to overestimate cancer risk. Similarly, the modeled ground water EEC reflects a bounding analysis which would not appreciately contri bute to aggregate risks at the lo w end but would represent a risk concern based on worse case assumptions. These uncertainties which likely overestimate exposure and risk, combined with the limited use area and reduction in the maximum application rate (50%), give the Agency reasonable assurance that aggregate cancer risks are not of concern.
**Occupational Risk**
Chlorpropham is currently under review for to lerance reassessment only. Occupational risk management decisions were made as part of the 1996 Chlorpropham RED, and no new data has been received to warrant reconsideration of these risks. Therefore, no occupational risk assessment was conducted.



### Ecological Risk8 Chlorpropham is currently under review for tolerance reassessment only. Ecological risk management decisions were made as part of the 1996 Chlorpropham RED, and no new data has been received to warrant reconsideration of these risks. Therefore, an ecological risk assessment was not conducted.



### Summary of Pending Data

• All product chemistry data requirements have been fulfilled for 1. Aceto 98% T (EPA Reg. No. 2749-102, 2. Cerexagri 99% T (EPA Reg. No. 2792-67), and 3.Pin Nip 98% T (EPA Reg. No. 65726-2) except data are required concerning UV/Visible Absorption (OPPTS 830.7050).
• The requirements for Analytical Methodology (OPPTS 860.1340) will remain unfulfilled until receipt of the revised version of the proposed GC/NPD method for tolerance enforcement in stored potato commodities.

• Method validation for HPLC/UV method for to lerance enforcement in stored potato commodities will remain unfulfilled for the re gistrant (Pin Nip, In c) until successful radiovalidation, confirmatory method, and independent laboratory validation have been submitted and reviewed.
• Separate enforcement methods (GC/MSD for chlorpropham and HPLC for 4-HSA) have been submitted for determination of chlorpr opham and its 4-HSA metabolite in meat and milk. Method validation for tolerance enfo rcement will remain unfulfilled until successful ILVs are submitted.
**Additional Generic Data Requirements**
• A special residue study (under crop fiel d trial guideline study number OPPTS 860.1500) is required to determine the potential for chlorpropham degradates to form and possibly deposit as residues in or on stored potatoes during application as a result of thermal degradation. The study is required because the Agency cannot determine whether or not the chlorophenyl isocyanate, or other thermal degradates, are produced during aerosol treatment (based on the literature citations and the submitted metabolism study alone). The study should include the range of temperatures typically used by the generators, at what temperature the decomposition products are formed during the pr ocess, and the presence and amount of any isocyanates (in particular, chlorophenyl isoncyanate, and 5-chloro-2-benzoxazolinone).
• The protocol for this study must be submitte d to the Agency prior to initiating the study. A residue analytical method may need to be developed, should existing methodology be insufficient. Technical registrants will be sent a Federal Insecticide, Fungicide, Rodenticide Act (FIFRA) Section 3(c)(2)(B) Data-Call -In (DCI) letter in a separate mailing.**Chlorpropham Summary**
**Use** • Chlorpropham is a plant growth regulator us ed for sprout control on post-harvest stored potatoes. • There is a Special Local Need (SLN) registration for use on post-harvest potatoes grown in high humidity areas in the state of Maine. • There are two SLN registrations for use on Easter lilies for floral bud removal and to decrease botrytis infection in limited acreage (about 150 acres annually), in two counties of Oregon and California. • There is also a SLN registration for flower bud/immature fruit removal on gingko trees in Washington, DC. • Annual usage of chlorpropham is approximately 445,600 pounds of active ingredient (a.i.). There are 3 technical grade formulations and 12 active end-use products. • Chlorpropham can be applied by: spray, low volume spray (concentrate), high pressure spray (dilute), stored commodity fumigation (aerosol), and stored commodity non-fumigation (aerosol).
**Risks**

• **Acute and chronic dietary (food) risk**is not of concern.

• **Cancer dietary (food) risk**for the general U.S. population is estimated to be 2.2 x 10 -6 which slightly exceeds the Agency’s level of concern for lifetime cancer risk of 1.0 x 10 -6 . However, because conservative surrogate data were used to estimate the cancer potency (Q 1 *), the Agency does not consider the chlorpropham dietary cancer risk to be of concern.

• **Drinking water dietary risk**is not of concern for surface water sources. The Easter lily ground water drinking water assessment suggests a potential cancer risk of concern for that very limited use. However mitigation measures provide sufficient assurance that cancer risks are not of concern for the limited Easter lily use. For ginko trees, the Agency is not concerned with potential acute or chronic exposure to ch lorpropham from surface or ground water sources of drinking water.

• **Residential risk** was not assessed. There are no registered residential uses for chlorpropham.

• **Acute and chronic aggregate (food and water) risks** are not of concern.

• **Aggregate** cancer risks for ground water suggest a risk concern. However mitigation measures combined with the conservatism in the asse ssment provide sufficient assurance that cancer risks are not of concern for the limited Easter lily use, the only area of potential concern.

• **Occupational and ecological risk** have not been assessed. Occupational and ecological risk management decisions were made as part of the 1996 chlorpropham reregistration eligibility decision (RED). No new data has been received to warrant reconsideration of these risks.