Pesticides; tolerances in food, animal feeds, and raw agricultural commodities: Forchlorfenuron,

[Federal Register: September 30, 2004 (Volume 69, Number 189)]

[Rules and Regulations]

[Page 58314-58322]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr30se04-17]

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[OPP-2004-0272; FRL-7681-5]

Forchlorfenuron; Pesticide Tolerance

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

SUMMARY: This regulation establishes a tolerance for residues of forchlorfenuron, N -(2-chloro-4-pyridinyl)-N'-phenylurea in or on grapes and kiwifruit. Siemer & Associates, Inc. on behalf of KIM-C1, LLC requested this tolerance under the Federal Food, Drug, and Cosmetic Act (FFDCA), as amended by the Food Quality Protection Act of 1996 (FQPA).

DATES: This regulation is effective September 30, 2004. Objections and requests for hearings must be received on or before November 29, 2004.

ADDRESSES: To submit a written objection or hearing request follow the detailed instructions as provided in Unit VI. of the SUPPLEMENTARY INFORMATION. EPA has established a docket for this action under Docket identification (ID) number OPP-2004-0272. All documents in the docket are listed in the EDOCKET index at http://www.epa.gov/edocket. Although

listed in the index, some information is not publicly available, i.e., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the Internet and will be publicly available only in hard copy form. Publicly available docket materials are available either electronically in EDOCKET or in hard copy at the Public Information and Records Integrity Branch (PIRIB), Rm. 119, Crystal Mall 2, 1801 S. Bell St., Arlington, VA. This docket facility is open from 8:30 a.m. to 4 p.m., Monday through Friday, excluding legal holidays. The docket telephone number is (703) 305-5805.

FOR FURTHER INFORMATION CONTACT: Dennis McNeilly, Registration Division (7505C), Office of Pesticide Programs, Environmental Protection Agency, 1200 Pennsylvania Ave., NW.,Washington, DC 20460-0001; telephone number: 703-308-6742; e-mail address:mcneilly.dennis@epa. gov.

SUPPLEMENTARY INFORMATION:

1. General Information

   1. Does this Action Apply to Me?

      You may be potentially affected by this action if you are an agricultural producer, food manufacturer, or pesticide manufacturer. Potentially affected entities may include, but are not limited to:

      Crop production (NAICS 111), e.g., agricultural workers; greehouse, nursery, and floriculture workers; farmers.

      Animal production (NAICS 112), e.g., cattle ranchers and farmers, dairy cattle farmers, livestock farmers.

      Food manufacturing (NAICS 311), e.g., agricultural workers; farmers; greenhouse, nursery, and floriculture workers; ranchers; pesticide applicators.

      Pesticide manufacturing (NAICS 32532), e.g., agricultural workers; commercial applicators; farmers; greenhouse, nursery, and floriculture workers; residential users.

      This listing is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be affected by this action. Other types of entities not listed in this unit could also be affected. The North American Industrial Classification System (NAICS) codes have been provided to assist you and others in determining whether this action might apply to certain entities. If you have any questions regarding the applicability of this action to a particular entity, consult the person listed under FOR FURTHER INFORMATION CONTACT.

      [[Page 58315]]

   2. How Can I Access Electronic Copies of this Document and Other Related Information?

      In addition to using EDOCKET (http://www.epa.gov/edocket/), you may

      access this Federal Register document electronically through the EPA Internet under the ``Federal Register'' listings at http://www.epa.gov/fedrgstr/. A frequently updated electronic version of 40 CFR part 180

      is available at E-CFR Beta Site Two at http://www.gpoaccess.gov/ecfr/.

      To access the OPPTS Harmonized Guidelines referenced in this document, go directly to the guidelines at http://www.epa.gpo/opptsfrs/home/guidelin.htm/ .

2. Background and Statutory Findings

   In the Federal Register of May 16, 2003 (68 FR 26607-26611) (FRL- 7303-2), EPA issued a notice pursuant to section 408(d)(3) of FFDCA, 21 U.S.C. 346a(d)(3), announcing the filing of a pesticide petition (PP 3F6550) by Siemer & Associates, 4672 W. Jennifer, Suite 103, Fresno, California 93722. The petition requested that 40 CFR 180.569 be amended by establishing a tolerance for residues of the plant growth regulator forchlorfenuron, N-(2-chloro-4-pyridinyl)-N'-phenylurea, in or on grapes, raisins and kiwifruit at 0.03 parts per million (ppm). That notice included a summary of the petition prepared by Siemer & Associates, Inc., the registrant. The proposed uses are the first section 3 tolerances for this new active ingredient. Time-limited tolerances are currently in effect (69 FR 48799-48805, Aug 11, 2004) for residues of forchlorfenuron in or on grapes, kiwifruit, apples, blueberries, cranberries, figs, pears, plums (fresh), olives and almonds. These time-limited tolerances were established in conjunction with the granting of an Experimental Use Permit (EUP) originally issued on May 21, 2001. The time-limited tolerances were first established in the Federal Register on May 7, 2001 (66 FR 22930-22936 (FRL 6781-4)). Agency review of the submitted residue studies indicate that higher tolerances are required for raisins at 0.06 ppm and kiwifruit at 0.04 ppm. There were no comments received in response to the notice of filing.

   Section 408(b)(2)(A)(i) of FFDCA allows EPA to establish a tolerance (the legal limit for a pesticide chemical residue in or on a food) only if EPA determines that the tolerance is ``safe.'' Section 408(b)(2)(A)(ii) of FFDCA defines ``safe'' to mean that ``there is a reasonable certainty that no harm will result from aggregate exposure to the pesticide chemical residue, including all anticipated dietary exposures and all other exposures for which there is reliable information.'' This includes exposure through drinking water and in residential settings, but does not include occupational exposure. Section 408(b)(2)(C) of FFDCA requires EPA to give special consideration to exposure of infants and children to the pesticide chemical residue in establishing a tolerance and to ``ensure that there is a reasonable certainty that no harm will result to infants and children from aggregate exposure to the pesticide chemical residue....''

   EPA performs a number of analyses to determine the risks from aggregate exposure to pesticide residues. For further discussion of the regulatory requirements of section 408 of FFDCA and a complete description of the risk assessment process, see the final rule on Bifenthrin Pesticide Tolerances (62 FR 62961, November 26, 1997) (FRL- 5754-7).

3. Aggregate Risk Assessment and Determination of Safety

   Consistent with section 408(b)(2)(D) of FFDCA, EPA has reviewed the available scientific data and other relevant information in support of this action. EPA has sufficient data to assess the hazards of and to make a determination on aggregate exposure, consistent with section 408(b)(2) of FFDCA, for a tolerance for residues of forchlorfenuron, N- (2-chloro-4-pyridinyl)-N'-phenylurea on grapes at 0.03 ppm; raisins at 0.06 ppm; and kiwifruit at 0.04 ppm. EPA's assessment of exposures and risks associated with establishing the tolerance follows.

   1. Toxicological Profile

      EPA has evaluated the available toxicity data and considered its validity, completeness, reliability as well as the relationship of the results of the studies to human risk. EPA has also considered available information concerning the variability of the sensitivities of major identifiable subgroups of consumers, including infants and children. The nature of the toxic effects caused by forchlorfenuron is discussed in Table 1 of this unit as well as the no-observed-adverse-effect-level (NOAEL) and the lowest-observed-adverse-effect-level (LOAEL) from the toxicity studies reviewed.

      Table 1.--Subchronic, Chronic, and Other Toxicity

      Guideline No.

      Study Type

      Results

      870.3100

      90 -day oral toxicity- rat NOAEL = M >= 400, F = 84 milligrams/ kilogram/day (mg/kg/day) LOAEL = M = not determined, F = 428: decrease BW gain and food efficiency mg/kg/ day

      870.3150

      90 day oral toxicity -dogs NOAEL = M = 16.8, F = 19.1 mg/kg/day LOAEL = M = 162.4, F = 188.7; decreases (>= 10%) in BW gain, FC and food efficiency mg/ kg/day

      870.3700

      Developmental tox-rat..... Maternal NOAEL = 200 mg/kg/day Maternal LOAEL = 400 mg/kg/day based on increased incidence of alopecia: decrease in BW and BW gains Developmental NOAEL = 200 mg/kg/day Developmental LOAEL = 400 mg/kg/day based on decreased mean fetal BW

      870.3700

      Developmental tox -

      Maternal NOAEL = >=100 mg/kg/day nonrodent.

      Maternal LOAEL = not determined Developmental NOAEL = >=100 mg/kg/day Developmental LOAEL = not determined

      [[Page 58316]]

      870.3800

      Reproduction and fertility Parental/Systemic NOAEL = M = 11/13, F= 13/ effects.

      15 mg/kg/day Parental/Systemic LOAEL = 144-202 mg/kg/day based on decreased FC in F0 and F1 M; clinical signs of toxicity and lower BW in F1 M and F and growth retardation in F1 and F2 pups Reproductive NOAEL = M = 144/168, F = 169/ 202 mg/kg/day Reproductive LOAEL = 544-926 mg/kg/day based on increased pup mortality (F1a, F1b and F2a), emaciation in F1b, and decrease in F2 pups/litter

      870.4300

      Chronic carcinogenicity NOAEL = M = 7, F = 9 mg/kg/day rat.

      LOAEL = M = 93, F = 122 mg/kg/day based on Reduced BW and BW gain and FC; kidney toxicity (M = suppurative inflammation, F = non-suppurative interstitial nephritis) No evidence of carcinogenicity

      870.4100

      1-year feeding study-dogs. NOAEL (in mg/kg/day): M = 87, F = 91 ........................................... LOAEL (in mg/kg/day): M = 195, F = 246, decreases in BW, BW gains and FC

      870.4200

      18-month carcinogenicity NOAEL (in mg/kg/day): M = 10.0, F = 9.9 study-mice.

      LOAEL (in mg/kg/day): M = 991.4, F = 1001.8, decreases in BW and BW gains in M and F Not carcinogenic

      870.7485

      Metabolism study-rat...... Recovery of 97% (M and F) by 168 hours. Absorbed dose 72-84%. Urine 62-74%. Feces 16-28%. Biliary excretion, 20-23% in bile. Urine and feces, elimination half-life 13.1-16.2 hours. Analyses identified parent and six metabolites in excreta. Parent not in urine and 1-2% in feces. Major metabolite forchlorfenuron-sulfate in urine of males (84%) and females (57%). Hydroxy forchlorfenuron (2 isomers) S9 Chinese Hamster CHO-KI cells 10, 20, 40, and 80 [mu]g/mL S9 activation.

      870.5550

      Unscheduled DNA synthesis No increase in unscheduled DNA synthesis in primary rat hepatocytes/mammalian cell cultures 0.1 to 30 7[mu]g/mL.

      870.5265

      Salmonella/mammalian

      Evidence of a positive response in tester activation gene mutation strain TA1535 in absence of S9 at 50, 100, assay.

      and 200 [mu]g/plate 10-1000 [mu]g/plate +S9... 2-200 [mu]g/plate -S9.....

      870.5265

      Salmonella/mammalian

      Evidence of induced mutany colonies over activation gene mutation background in tester strain TA1535 in assay.

      absence of S9 10-1,000 [mu]g/plate +S9.. 2-200 [mu]g/plate -S9.....

   2. Toxicological Endpoints

      The dose at which no adverse effects are observed (the NOAEL) from the toxicology study identified as appropriate for use in risk assessment is used to estimate the toxicological level of concern (LOC). However, the lowest dose at which adverse effects of concern are identified (the LOAEL) is sometimes used for risk assessment if no NOAEL was achieved in the toxicology study selected. An uncertainty factor (UF) is applied to reflect uncertainties inherent in the extrapolation from laboratory animal data to humans and in the variations in sensitivity among members of the human population as well as other unknowns. An UF of 100 is routinely used, 10X to account for interspecies differences and 10X for intraspecies differences.

      Three other types of safety or uncertainty factors may be used: ``Traditional uncertainty factors;'' the ``special FQPA safety factor;'' and the ``default FQPA safety factor.'' By the term ``traditional uncertainty factor,''

      [[Page 58317]]

      EPA is referring to those additional uncertainty factors used prior to FQPA passage to account for database deficiencies. These traditional uncertainty factors have been incorporated by the FQPA into the additional safety factor for the protection of infants and children. The term ``special FQPA safety factor'' refers to those safety factors that are deemed necessary for the protection of infants and children primarily as a result of the FQPA. The ``default FQPA safety factor'' is the additional 10X safety factor that is mandated by the statute unless it is decided that there are reliable data to choose a different additional factor (potentially a traditional uncertainty factor or a special FQPA safety factor).

      For dietary risk assessment (other than cancer) the Agency uses the UF to calculate an acute or chronic reference dose (acute RfD or chronic RfD) where the RfD is equal to the NOAEL divided by an UF of 100 to account for interspecies and intraspecies differences and any traditional uncertainty factors deemed appropriate (RfD = NOAEL/UF). Where a special FQPA safety factor or the default FQPA safety factor is used, this additional factor is applied to the RfD by dividing the RfD by such additional factor. The acute or chronic Population Adjusted Dose (aPAD or cPAD) is a modification of the RfD to accommodate this type of safety factor.

      For non-dietary risk assessments (other than cancer) the UF is used to determine the LOC. For example, when 100 is the appropriate UF (10X to account for interspecies differences and 10X for intraspecies differences) the LOC is 100. To estimate risk, a ratio of the NOAEL to exposures (margin of exposure (MOE) = NOAEL/exposure) is calculated and compared to the LOC.

      The linear default risk methodology (Q*) is the primary method currently used by the Agency to quantify carcinogenic risk. The Q* approach assumes that any amount of exposure will lead to some degree of cancer risk. A Q* is calculated and used to estimate risk which represents a probability of occurrence of additional cancer cases (e.g., risk). An example of how such a probability risk is expressed would be to describe the risk as one in one hundred thousand (1 X 10-\5\), one in a million (1 X 10-\6\), or one in ten million (1 X 10-\7\). Under certain specific circumstances, MOE calculations will be used for the carcinogenic risk assessment. In this non-linear approach, a ``point of departure'' is identified below which carcinogenic effects are not expected. The point of departure is typically a NOAEL based on an endpoint related to cancer effects though it may be a different value derived from the dose response curve. To estimate risk, a ratio of the point of departure to exposure (MOEcancer= point of departure/exposures) is calculated.

      A summary of the toxicological endpoints for forchlorfenuron used for human risk assessment is shown in the following Table 2:

      Table 2.--Summary of Toxicological Dose and Endpoints for Forchlorfenuron for Use in Human Risk Assessment

      Exposure Scenario

      Dose(mg/kg/day)

      Endpoint

      Study

      Acute Dietary

      NOAEL - assumed to be aPAD = 1.0 mg/kg/day Rabbit developmental 100

      study UF = 100...............

      Chronic Dietary

      NOAEL = 7.0

      Decreases in body

      2-year rat feeding weight, body weight study gain and food consumption as well as effects on the kidney at the LOEAL of 93 and 122 mg/ kg/day for males and females, respectively.

      UF = 100

      Chronic RfD = 0.07 mg/ NA FQPA = 1x.............. kg/day Chronic Population- Adjusted Dose (cPAD) = 0.07 mg/kg/day; apply to all population subgroups.

      Short-Term (Dermal)

      NOAEL = 200

      Decreases in maternal developmental rat study body weights and body weight gains as well as a decrease in mean fetal body weights.

      Intermediate-Term (Dermal)

      NOAEL = 87

      Based on decreases in 1-Year feeding study in body weight, bw gain, dogs and food consumption.

      Long-Term (Dermal)

      NA

      Based on the limited NA use, long-term exposure is not expected anda risk assessment not conducted

      Short-Term (Inhalation)

      NOAEL = 200

      Same as short-term developmental rat study dermal

      Intermediate-Term (Inhalation)

      NOAEL = 87

      Same as intermediate- 1-Year feeding study in term dermal

      dogs

      [[Page 58318]]

      Long-Term (Inhalation)

      NA

      Based on the limited NA use, long-term exposure is not expected anda risk assessment not conducted

      Cancer

      NA

      Not likely to be a NA human carcinogen

   3. Exposure Assessment

      1. Dietary exposure from food and feed uses-- i. Acute exposure. In conducting this acute dietary risk assessment the Lifeline Model Version 2.0 and the Dietary Exposure Evaluation Model (DEEMTM, Version 2.03) analysis evaluated the individual food consumption as reported by respondents in the USDA 1994-1996 and 1998 Nationwide Continuing Surveys of Food Intake by Individuals (CSFII) and accumulated exposure to the chemical for each commodity. The following assumptions were made for the acute exposure assessments: Tolerance-level residues and 100% crop treated assumptions were used. DEEM (Version 7.81) default processing factors were used to modify the tolerance values for processed commodities for which separate tolerances are not being established.

         ii. Chronic exposure. In conducting this chronic dietary risk assessment the Lifeline Model Version 2.0 and the DEEMTM analysis evaluated the individual food consumption as reported by respondents in the USDA 1994-1996 and 1998 Nationwide Continuing Surveys of Food Intake by Individuals (CSFII) and accumulated exposure to the chemical for each commodity. The following assumptions were made for the chronic exposure assessments: A conservative chronic dietary exposure analysis was performed for the general U.S. population and various population subgroups. Tolerance-level residues and 100% crop treated assumptions were used. The 1-in-10-year average surface water concentration from the Pesticide Root Zone Model/Exposure Analysis Modeling System (PRZM-EXAMS) Model was used as a point estimate for drinking water in the dietary analyses.

         iii. Cancer. A quantitative cancer dietary exposure assessment is not needed for forchlorfenuron since it is not a carcinogen.

      2. Dietary exposure from drinking water. The Agency usesthe FQPA Index Reservoir Screening Tool (FIRST) or the PRZM/EXAMS, to produce estimates of pesticide concentrations in an index reservoir. The screening concentration in ground water (SCI-GROW) model is used to predict pesticide concentrations in shallow ground water. For a screening-level assessment for surface water EPA will use FIRST (a tier 1 model) before using PRZM/EXAMS (a tier 2 model). The FIRST model is a subset of the PRZM/EXAMS model that uses a specific high-end runoff scenario for pesticides. Both FIRST and PRZM/EXAMS incorporate an index reservoir environment, and both models include a percent crop area factor as an adjustment to account for the maximum percent crop coverage within a watershed or drainage basin.

         None of these models include consideration of the impact processing (mixing, dilution, or treatment) of raw water for distribution as drinking water would likely have on the removal of pesticides from the source water. The primary use of these models by the Agency at this stage is to provide a screen for sorting out pesticides for which it is unlikely that drinking water concentrations would exceed human health levels of concern.

         Since the models used are considered to be screening tools in the risk assessment process, the Agency has generally not used estimated environmental drinking water concentrations (EDWCs), which are the model estimates of a pesticide's concentration in water. EDWCs derived from these models are used to quantify drinking water exposure and risk as a %RfD or %PAD. Instead, drinking water levels of comparison (DWLOCs) are calculated and used as a point of comparison against the model estimates of a pesticide's concentration in water. DWLOCs are theoretical upper limits on a pesticide's concentration in drinking water in light of total aggregate exposure to a pesticide in food, and from residential uses. Since DWLOCs address total aggregate exposure to forchlorfenuron they are further discussed in the aggregate risk Unit III. E. below.

         As EPA has gathered more information regarding pesticide residues in drinking water and drinking water consumption amounts, it has been working toward refining the screening-level DWLOC approach to conducting aggregate risk assessments that combine exposures across all pathways. As a first step in this process, EPA has begun using the chronic and cancer EDWCs directly in chronic and cancer dietary exposure assessments to calculate aggregate dietaryfood + water risk. This is done by using the relevant PRZM-EXAMS value as a residue for water (all sources) in the dietary exposure assessment. The principal advantage of this approach is that the actual individual body weight and water consumption data from the Continuing Survey of Food Intake by Individuals (CSFII) are used, rather than assumed weights and water consumption for broad age groups.

         Accordingly, the 1-in-10-year average surface water concentration from the PRZM-EXAMS Model was used as a point estimate for drinking water in the chronic dietary analysis. Estimated concentrations in drinking water were not included in the acute analysis. Instead, the maximum allowable exposure from drinking water was calculated by subtracting the exposure in food from the total allowable exposure. The maximum allowable exposure from drinking water is converted to the maximum allowable drinking water concentration, or DWLOCs. These values are then compared to the estimated drinking water concentrations.

         Based on the PRZM/EXAMS and SCI-GROW models, the EDWCs of forchlorfenuron for chronic exposures are estimated to be 0.32 parts per billion (ppb) for surface water and 0.003 ppb for ground water. Based on the PRZM/EXAMS and SCI-GROW models, the EDWCs of forchlorfenuron for acute exposures are estimated to be 0.54 ppb for surface water and 0.003 ppb for ground water.

      3. From non-dietary exposure. The term ``residential exposure'' is used in

         [[Page 58319]]

         this document to refer to non-occupational, non-dietary exposure (e.g., for lawn and garden pest control, indoor pest control, termiticides, and flea and tick control on pets).

         Forchlorfenuron is not registered for use on any sites that would result in residential exposure.

      4. Cumulative effects from substances with a common mechanism of toxicity. Section 408(b)(2)(D)(v) of FFDCA requires that, when considering whether to establish, modify, or revoke a tolerance, the Agency consider ``available information'' concerning the cumulative effects of a particular pesticide's residues and ``other substances that have a common mechanism of toxicity.''

         Unlike other pesticides for which EPA has followed a cumulative risk approach based on a common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding as to forchlorfenuron and any other substances and forchlorfenuron does not appear to produce a toxic metabolite produced by other substances. For the purposes of this tolerance action, therefore, EPA has not assumed that forchlorfenuron has a common mechanism of toxicity with other substances. For information regarding EPA's efforts to determine which chemicals have a common mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see the policy statements released by EPA's Office of Pesticide Programs (OPP) concerning common mechanism determinations and procedures for cumulating effects from substances found to have a common mechanism on EPA's web site at http://www.epa.gov/pesticides/cumulative/ .

   4. Safety Factor for Infants and Children

      1. In general. Section 408 of FFDCA provides that EPA shall apply an additional tenfold margin of safety for infants and children in the case of threshold effects to account for prenatal and postnatal toxicity and the completeness of the database on toxicity and exposure unless EPA determines based on reliable data that a different margin of safety will be safe for infants and children. Margins of safety are incorporated into EPA risk assessments either directly through use of a MOE analysis or through using uncertainty (safety) factors in calculating a dose level that poses no appreciable risk to humans. In applying this provision, EPA either retains the default value of 10X when reliable data do not support the choice of a different factor, or, if reliable data are available, EPA uses a different additional safety factor value based on the use of traditional uncertainty factors and/or special FQPA safety factors, as appropriate.

      2. Prenatal and postnatal sensitivity. There is a lack of increased qualitative or quantitative susceptibility in developmental or reproductive studies. There are no concerns and no residual uncertainties with regard to pre-and/or postnatal toxicity.

      3. Conclusion. As indicated, available data do not show any increased susceptibility to the young from exposure to forchlorfenuron and there are no residual uncertainties regarding pre- or post-natal toxicity. There is an adequate toxicity database for forchlorfenuron. As there was no evidence of neurotoxicity, it is not necessary to require a developmental neurotoxicity study. In addition, data used to evaluate exposure are adequate, and conservative assumptions are being used to evaluate aggregate exposure through food and drinking water. As a result, exposures are probably considerably overestimated. Accordingly, EPA concludes it has reliable data supporting removal of the additional FQPA 10-fold safety factor for the protection of infants and children.

   5. Aggregate Risks and Determination of Safety

      To estimate total aggregate exposure to a pesticide from food, drinking water, and residential uses, the Agency either calculates DWLOCs which are used as a point of comparison against EDWCs or uses the EDWCs directly in the aggregate exposure assessment. DWLOC values are not regulatory standards for drinking water. DWLOCs are theoretical upper limits on a pesticide's concentration in drinking water in light of total aggregate exposure to a pesticide in food and residential uses. In calculating a DWLOC, the Agency determines how much of the acceptable exposure (i.e., the PAD) is available for exposure through drinking water [e.g., allowable chronic water exposure (mg/kg/day) = cPAD - (average food + residential exposure). This allowable exposure through drinking water is used to calculate a DWLOC.

      A DWLOC will vary depending on the toxic endpoint, drinking water consumption, and body weights. Default body weights and consumption values as used by the EPA's Office of Water are used to calculate DWLOCs: 2 liter (L)/70 kg (adult male), 2L/60 kg (adult female), and 1L/10 kg (child). Default body weights and drinking water consumption values vary on an individual basis. This variation will be taken into account in more refined screening-level and quantitative drinking water exposure assessments. Different populations will have different DWLOCs. Generally, a DWLOC is calculated for each type of risk assessment used: Acute, short-term, intermediate-term, chronic, and cancer. As explained above, however, EPA is beginning to use EDWCs directly in estimating aggregate exposure in chronic and cancer assessment.

      When EDWCs for surface water and ground water are less than the calculated DWLOCs, OPP concludes with reasonable certainty that exposures to the pesticide in drinking water (when considered along with other sources of exposure for which OPP has reliable data) would not result in unacceptable levels of aggregate human health risk at this time. Because OPP considers the aggregate risk resulting from multiple exposure pathways associated with a pesticide's uses, levels of comparison in drinking water may vary as those uses change. If new uses are added in the future, OPP will reassess the potential impacts of residues of the pesticide in drinking water as a part of the aggregate risk assessment process.

      1. Acute risk. From the Lifeline Model, the U.S. population and all population subgroups had risk estimates that were below 1% of the acute population adjusted dose (aPAD) from exposure to forchlorfenuron in food. The most highly exposed population subgroup was children 1-2 years old, which had a risk estimate of 0.08% of the aPAD. The general U.S. population utilized 0.02% of the aPAD. In addition, there is potential for acute dietary exposure to forchlorfenuron in drinking water. After calculating DWLOCs and comparing them to the EDWCs for surface and ground water, EPA does not expect the aggregate exposure to exceed 100% of the aPAD, as shown in the following Table 3:

         [[Page 58320]]

         Table 3.--Aggregate Risk Assessment for Acute Exposure to Forchlorfenuron

         Surface Water Ground Water Acute DWLOC Population Subgroup

         % aPAD (Food) EDWCs (ppb) EDWCs (ppb)

         (ppb)

         U.S. Population

         0.000157

         0.54

         0.003

         35,000

         All Infants

         0.000526

         0.54

         0.003

         10,000

         Children 1-2 years

         0.000846

         0.54

         0.003

         10,000

         Children 3-5 years

         0.000557

         0.54

         0.003

         10,000

         Children 6-12 years

         0.000217

         0.54

         0.003

         10,000

         Youth 13-19 years

         0.000089

         0.54

         0.003

         30,000

         Adults 20-49 years

         0.000101

         0.54

         0.003

         35,000

         Adults 50+ years

         0.000105

         0.54

         0.003

         35,000

         Females 13-49

         0.000112

         0.54

         0.003

         30,000

         \1\ Maximum Allowable Water Exposure = PAD - sum of all quantifiable exposures. \2\ Drinking Water Level of Comparison = Maximum Allowable Water Exposure x Body Weight (10 kg infants and children, 60 kg females, 70 kg all others) x 1,000 [mu]g/mg / Consumption (1 L/day infants and children, 2 L/ day all others).

      2. Chronic risk. The U.S. population and all population subgroups had risk estimates that were below 1% of the chronic population adjusted dose (cPAD) from exposure to forchlorfenuron in food. The most highly exposed population subgroup was children 1-2 years old, which had a risk estimate of 0.3% of the cPAD. There are no residential uses for forchlorfenuron that result in chronic residential exposure to forchlorfenuron. Based on the use pattern, chronic residential exposure to residues of forchlorfenuron is not expected. However, there is potential for chronic dietary exposure to forchlorfenuron in drinking water. The Agency does not expect the aggregate exposure to exceed 100% of the cPAD, as shown in Table 4 of this unit:

         Chronic (non-cancer) aggregate risk is the sum of exposures resulting from chronic dietary food + chronic drinking water + chronic residential uses. Forchlorfenuron has no registered or proposed residential uses. Therefore, this risk assessment is the aggregate of chronic food and chronic drinking water exposures only. As stated above, the drinking water EDWCs were included in the dietary exposure analysis. As a result, the aggregate risk assessment is equivalent to the dietary analysis, the results of which are reported in Table 4 below. The results of the DEEM-FCID analysis were comparable to those of the Lifeline analysis. In the DEEM-FCID analysis, the general U.S. population and all population subgroups used