UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D

. C. 2046 0

MEMORANDUM

DATE: March 18,2014 OFFICE OF CHEMICAL SAFETY AND

POLLUT I ON PREVENTION

SUBJEC T: RESPONSE TO COMMENTS. The Hea l th Effec t s Division 's Response t o
Pest i cide Action Network North America on the Chloropicrin Registration

Review Scoping Document for Human Risk Assessment (O PP Docket# EPA-HQOPP-20 13-0 153).

PC Code: 081501

D ecisi o n No.:**'fi5!9~** Pe titi on N o. : NJA

Ri s k A ssess m e nt Ty p e: Single Chemical/Aggregate

TX R No.: N /A

MRI D No

. : N / A

FROM: Shalu Shelat, Industrial Hygieni st
Risk Assess ment Branch VI

and

Monique Pe r ro n
, S. D.

, Toxicologist

Risk Assessmen t Br a n ch I

Health Effec ts Division (7509P) DP B a r code: 0416740 Reg i stra tion No.: N/A

Re gulato ry Actio n : Re gistrat ion Review

Case N o

. : 0040

CAS No.: 76-06-2

40 CF R: N/A

THRU : Charles Smith, Branch Chief 

# c_

_ f?**~** Risk Assessment Branch I

## ~ - Health Effec ts Division (7509P)

TO: Carolyn Schroder, Chem i ca l Review Manager

Risk Management and Implementation Br an ch I V (7508P)

Pest ic ide Re-eva l uat i on Division

In response to the letter s ubmitted by the Pestic i de Action Network North America (PANNA) in regards to the use and application of fumigants as part of the chloropicrin Preliminary Work Plan 

### (Docket I D No. EPA- H Q-OPP-2013

- 0153).

Page 1 of 18I) Levels of concern must be reevaluated: US EPA needs to reevaluate the points of departure (PODs) and uncertainty factors (UFs) used for the residential and occupational

exposure assessments. The acute level of concern of73 ppb averaged over 8 hours is not sufficiently protective, a point that was clearly made in the California review and by US

EPA's Human Subjects Review Panel. Since chloropicrin has short-term irritant properties, the acute level of concern is also relevant for short-term exposures, as recognized by DPR in their Risk Characterization document.

EPA Response:

As stated by the Agency in th e Health Effects Division 2009 Response to Comments on the 2008 Reregistration Eligib ility Documents (D348636, May 14, 2009), the Agency has relied on three key guidance/framework documents for consideration of mode of action and refinement of the intraspecies factor for ch l oropicrin. These guidance and framework documents which focus on mode of action and kinetic and mechanistic data to refine inter-species and intra-species extrapolation factors have been outlined in a chloropicrin memo (Reaves and Lowit, 0293356,

TXR 0054860

, 06118/08). This memorandum considered toxicokinetics, dynamics and mode of

action as well as the level at which individuals in the popu l ation detect and become irritated to chloropicrin. All of this information was considered in the refinement of the intraspecies factor.

The BMCL10 or NOAEL of73 ppb is protective of all individuals without an i nclusion of intraspecies factor since it is 2-fold below a level that the most sensitive subpopulation was beginning to detect chloropicrin without direct irritation ( 150 ppb ). The point of departure (0

. 073 ppm) is 145-fold lower than the acute rodent inhalation study (1 0.6 ppm), 14-fold lower

than irritation produced in repeat inhalation rodent studies (1.0 ppm) and 14-fold lower than

acute eye and respiratory effects observed in incident reports (1.0 ppm).

The PANNA comments also discuss the differences between the California DPR toxico logy

database conclusions and those of the Agency. The Agency, as discussed in the cited memo, has

relied on human data for the acute ( 1-24 hour) point of departure with the endpoint based on eye irritation. The DPR approach uses a different endpoint of increased nitric oxide (NO) in expired

nasal air from the same human study for the acute (I hour) point of departure and in addition

, DPR retained the 1 OX intraspecies uncertainty factor. DPR also selected a separate acute (8 and

24 hour) point of departure from a developmental rabbit toxicity study which included I OX intraspecies and interspecies uncertainty factors.

The Agency maintains that the chloropicrin risk assessment is sufficiently protective and utilizes

the most appropriate points of departure and safety factors.

2) The bystander exposure assessment must be re-done: The Office of Pesticide Programs should eliminate any use of the "whole field" method of exposure assessment
that averages concentrations and results in

. substantially underestimated exposure predictions

. The "maximum direction" method used by CDPR should be utilized instead

because it provides a more realistic estimate of worst-case (but very common) bystander

exposures downwindjrom a.fumigation application. In addition, the ISCST3 model on which P ERFUM is based is out of date, and US EPA 's Office of Air and Radiation

Page 2 of 18Page 3 of 18

indicates that the current preferred models for atmospheric exposure assessments are

either AERMOD or CALPUFF. These models will better handle cal m wind conditions.

EPA Response:

In the 2009 amended REDs for the soil fumigants, the Agency used a weight of evidence approach to develop the buffer zone distances which included consideration of the hazard profile of the fumigants, information from inci dent reports, monitoring data, stakeholder comments along with comprehensive analysis of results from PERFUM modeling and consideration of results using other models. The analysis of PERFUM results considered distances at various percentiles of the whole field and maximum distance distributions, and Margins of Exposure (MOEs) for various distances. EPA’s goal for risk management was to achieve a buffer distance where associated risks were at or below target concentration levels at high percentiles of

expo sure. In other words, at the outer edge of the buffer zone surrounding an application site, the probability of exposure is extremely low.

The Office of Pesticide Programs (OPP) recognizes that different parts of the Agency use

different models for atmo spheric exposure assessments. OPP has previously conducted a preliminary comparative evaluation of the differences in outputs between the current version of

PERFUM (based on ISCST3) and an evaluation version of PERFUM (based on AERMOD) and

in most cases t he analysis indicates very similar buffer distance predictions. In addition, OPP has also previously conducted a preliminary comparative evaluation of the differences in outputs between the current version of PERFUM (based on ISCST3) and the FEMS model (b ased on CALPUFF) and in most cases the analysis indicates very similar buffer distance predictions. For most of the instances were small differences in buffer distance predictions were seen, use of AERMOD or CALPUFF as the base model resulted in slightly smaller buffer distance predictions. This indicates that the use of PERFUM (based on ISCST3) in the chloropicrin risk assessment should be considered health protective

.

3) The carcinogenicity of chloropicrin must be reevaluated: Significant concerns we re raised by the DPR toxicologists, OEHHA toxicologists, and the SRP members regarding the carcinogenicity of chloropicrin. DPR management’s classification of chloropicrin carcinogenicity as “equivocal” is in contradiction to the conclusions reached by DPR and OEHHA scientists and the SRP, a point we discuss at greater length below. For the chloropicrin reregistration, US EPA did not conduct an assessment of the carcinogenicity of chloropicrin stating that: “ . . . chloropicrin is currently not considered a carcinogen by the inhalation route of exposure since there is no evidence of increased tumorigenesis after chronic inhalation exposure.” This is incorrect. There is substantial evidence of carcinogenicity from less

- than

- lifetime

mouse and rat inhalation s tudies. Less

- than

- lifetime studies are well known to have reduced sensitivity for determining the statistical significance of observed effects. In consideration of the fact that mutagenicity studies and a number of oral

- dose animal studies provide data ind icating that chloropicrin is a potent carcinogen, US EPA must reevaluate its carcinogenicity. Because the existing studies were so poorly conducted, it may be necessary for US EPA to call in an additional lifetime inhalation cancer study.Page 4 of 18

EPA Response:

Th e Agency has reviewed the data submitted in regards to the carcinogenicity of chloropicrin. In

a letter (see Attachment 1 ) submitted to the Department of Pesticide Regulation (E. Reaves; 11/9/09) , the Agency provided an analysis of the data that DPR relied on for the mutagenic and carcinogenic classification of chloropicrin. In this analy sis, the Agency has stated that both agencies are using the same cancer data ; however

, there are key differences in the approaches

used to determine the classification of chloropicrin. In regards to the mutagenicity determination, in vitro mutagenicity assays for chloropicrin have mixed positive and negative results; however, in vivo data for chloropicrin are negative.

The Agency determine d the chronic mouse inhalation st udy (MRID 436 3 2201) is adequate for use in risk assessment and was analyzed consistent with procedures under the Can cer Review Committee (CARC) (Bru nsman, 2009; TXR 0055260). Although DPR and OEHHA have provided conclusions that chloropicrin is carcinogen ic through the inhalation route, the Agency believes that there is no concern for the carcinogenic potential for chloropicrin based on a

number of considerations: 1) no lung tumors were seen in male or female rats exposed to the same exposure concentratio ns for a longer period of time (104 weeks) in the same laboratory; 2) no increase in lung tumors was seen in male mice; and 3) the weak response in female mice ( i.e.

, the presence of a single common tumor that lacked biological or statistical significance with no increase in the proportion of malignant tumors nor decrease in the time to tumor occurrence). In addition, in the event that long

- term or chronic exposure is expected, the long

- term Human Equivalent Concentration (HEC) of 0.004 ppm would be used. The HEC is 250 fold lower than the concentration that induced biologically insignificant lung tumors and would be protective of any potential carcinogenicity from inhalation exposure to chloropicrin.

As a model of cancer risks assessed on an age

- adjusted basis, PANNA submitted the report on chloropicrin air monitoring conducted in Sisquoc, California. The Agency has previously provided comments on the monitoring study and analysis results as part of the 2009 Response to Comments on the 2008 Reregistration Eligibility Documents (D348636, May 14, 2009). Any

conclusions that PANNA has drawn in r egards to air concentrations have limitations based on the comments provided in 2009. The s e limitations include the lack of availability of the raw study data, vari ations in the sampler flow rates, and lack of valid methods for quantifying chloropicrin

air concentrations (i.e., use of the highest sample volume as the basis for air concentrations calculations) . In addition, the Agency has not determined chloropicrin to have mutagenic effects

in the in vitro system; therefore, an age

- adjusted cancer risk approach would not be appropriate. EPA guidance requires age

- dependent adjustment factors to be applied to children's cancer exposure only for carcinogenic pesticides that have been shown to have a mutagenic mode of

action

. The Agency's policies on conducting cancer risk assessments are contained in Guidelines for Carcinogen Risk Assessment 1 and Supplemental Guidance for Assessing Susceptibility from Early

- Life Exposu re to Carcinogens 2

.

1 Available at: http://www.epa.gov/raf/publications/pdfs/CANCER_GUIDELINES_FINAL_3

- 25

- 05.PDF

2 Available at: http://www.epa.gov/ttn/atw/childrens_supplement_final.pdfPage 5 of 18

4) Chloropicrin cannot be used safely

— it should not be re

- registered. However, if EPA allows its continued use, buffer zones will need to be reevaluated: Based on changes in 1), 2) and potentially 3) above, buffer zones will need to b e recalculated, and mitigations to protect handlers will need to be reassessed to be protective of human health. However, we think it is likely that mitigations that would prevent unreasonable adverse effects on human health or the environment will not pro ve possible, let alone practical, so chloropicrin re

- registration will not be supportable.

EPA Response:

The Agency reviews the use of pesticides in accordance with labels and best practices information. The Agency also takes into consideration incident s that may result in the modification of label allowances or restrictions. If information is provided that indicates certain label restrictions or application practices are not being met due to the nature of the application, the Agency will consider the m odifications to the labels that may be necessary to ensure the health and safety of the individuals affected. In general, b uffers will be reevaluated at the time of registration review and will take into consideration any changes in the exposure modeling or toxicological database at that time.

The waiting time between fumigation and tarp cutting activities has been measured in one study that was provided to the Agency by DPR. The Agency agreed with DPR that exposure concentrations were greater than prev iously assessed at the time of tarp cutting. The Agency has requested additional information from DPR and is awaiting their analysis in order to provide a comprehensive assessment of the tarp cutting issue.

The modeling programs used to predicted buffers after the application of fumigants, takes into consideration the varying wind patterns and stagnation that may occur in the days following an application. The good agricultural practices that are required during all applications are intended

to reduce ex posure but also provide the best conditions to make an efficient application of a fumigant.

5) Fumigant use is costly in many ways, and promising alternatives are available: Fumigations are expensive, with many of the costs externalized to neighbors and farm workers. California is aggressively pursuing alternatives to fumigants, with encouraging results. US EPA BEAD should evaluate these methods when they do their economic risk/benefit assessment for the use of chloropicrin.

EPA Response:

The soil fumi gants have been among the most widely used pesticides in the US, and its use provides benefits to both food consumers and growers. In determining the reregistration eligibility for chloropicrin, the Biological and Economic Analysis Division (BEAD) conduct ed a number of benefits assessments for the fumigants by crop, and these are located in the chloropicrin RED docket at EPA

- HQ

- OPP

- 2007

- 0350. In the Summary of Benefits of Soil Fumigation with Chloropicrin (EPA

- HQ

- OPP

- 2007

- 0350

- 0017), the Agency acknowledg ed therePage 6 of 18

may be registered pesticide alternatives to chloropicrin available depending on the crop, but the alternatives may not control the full suite of pests. In addition, alternatives frequently cited for chloropicrin are other fumigants.

However, P ANNA is correct that non

- chemical alternatives are being explored and developed as has been noted in the critical use exemption responses to the methyl bromide phase

- out. Anaerobic soil disinfestation (ASD), soil substrate amendments, steam treatment, and others have potential for replacing some portion of currently fumigated land. If PANNA is aware of additional data on fumigant alternatives, please consider submitting this information to the Agency for consideration. Through the registration review pro cess, the Agency will revisit the mitigation measures from the REDs and update any benefits and alternatives assessments as

needed.

6) The risk assessment results need to be more clearly communicated: The 2009 US EPA Reregistration Eligibility Decision (RED) document for chloropicrin is poorly written, with important terms and abbreviations left undefined, and substantial inaccuracies in the summaries of the toxicology studies. In particular, US EPA does not even provide a term for concentrations of conc ern. It is important to include such a term to provide language for discussing the risk assessment. In the past, EPA has called these regulatory endpoints Reference Concentrations (RfCs), and in 2002, EPA Office of Research and Development (ORD) suggested new language for use in labeling endpoints and regulatory target concentrations that more clearly defines exposure route and duration. We urge EPA to adopt ORD’s suggested language and clean up the risk assessment in order to clearly communicate the scienc e

.

EPA Response: The Agency will take into consideration the comment provided in regards to clarity of the document in any future correspondences.Page 7 of 18



## Attachment 1: U.S. EPA Memo with Comments on CDPR

Chloropicrin Cancer AssessmentPage 8 of 18 ENVIRONMEN TAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

November 9, 2009

Carolyn Lewis California Department of Pesticide Regulation 1001 I Street, P.O. Box 4015 Sacramento, CA 95812

- 4015

Re: U.S. EPA Comments On CDPR Chloropicrin Cancer Assessment

Dear Carolyn Lewis

,

The attached/enclosed document is in response to your request to review the draft cancer assessment that CDPR provided to the Agency. The document and section we reviewed can be identi fied by the following information:

 Evaluation of Chloropicrin As A Toxic Air Contaminant. Part B. Human Health Assessment. June 1, 2009. Section III.A.4. Carcinogenicity

- Weight of Evidence.

Our review specifically addresses the cancer aspects of the ass essment for chloropicrin (Attachment A and B). It should be noted that lack of comments by the Agency on the other sections of the CDPR’s human health assessment is not an endorsement by the Agency.

Our findings indicate that our agencies are essentially using the same cancer data as the basis for our individual cancer assessments but the use of the information differs between agencies. These different approaches have resulted in different predictions of cancer risk. The key differences between the appr oaches identified include: differences in the uncertainties regarding the mutagenicity data and determination of a mutagenic mode of action, differences in the statistical analyses used to determine the significance of female mouse lung tumor data; differ ences in the determination of the biological significance of the tumor data; and differences in the use of a quantitative assessment for cancer via the inhalation route. It is noted that a formal Cancer Review Committee (CARC) will be

scheduled for chloro picrin during the Agency’s Registration Review process.

We understand that the chloropicrin human health document by the Department is still considered draft. It is our hope that the cancer review document which we have prepared will be utilized in the

c onsideration of the final cancer assessment. Please let me know if you have comments, questions or require further clarifications on this submission.

Sincerely, Elissa Reaves, Ph.D. Toxicologist, USEPA/OPP/HEDPage 9 of 18 

## Attachment A

The Health Effects Division ( HED) was asked to comment on the cancer assessment performed by the California Department of Pesticide Regulation (CDPR) for chloropicrin. HED has reviewed the draft CDPR document dated June 1, 2009.

Below is HEDs detailed response to CDPRs cancer assess ment.

A. HED’s comments on Genotoxicity for Chloropicrin

HED agrees with CDPR that the results of the genotoxicity studies are mixed. Chloropicrin was tested in a battery of standard genotoxicity and mutagenicity tests in vitro. The battery included

accep table FIFRA guideline studies for the Ames assay in Salmonella typhimurium, gene mutation in cultured mouse lymphoma cells, chromosomal aberration assay in Chinese hamster ovary (CHO) cells and unscheduled DNA synthesis (UDS) in rat hepatocytes. There is convincing evidence from the submitted bacterial reverse mutation assay (San and Wagner 1990, MRID 41960801) and the open literature (Haworth et al., 1983; Giller et al., 1995) that chloropicrin is mutagenic in Salmonella typhimurium TA 98 and TA100. The response is enhanced when the test agent was subjected to the pre

- incubation modification to the standard “Ames” test. Evidence provided by Schneider et al. (1999) also shows that chloropicrin is converted to active dechlorinated metabolites (possibly CHC l 2 NO 2 and/or CH 2 ClNO 2 ) in the presence of glutathione (GSH) alone or complete S9 cofactor mix but not when washed microsomes from the S9 liver homogenate are used as the sole source of P450 enzymes. It, therefore, appears that GSH is more important than P 450 in the initial metabolism of chloropicrin. However, the evidence of mutagenicity is limited to the microbial test system as indicated by the lack of a mutagenic or clastogenic effect in mammalian cells (San and Sigler 1990, MRID 41960803; Putnam and M orris 1990, MRID 41960802; Curren 1990, MRID 41060804). The positive results from the in vitro chromosome assay (Putman and Morris 1990, MRID 41960802) using CHO cells as the target organism was revisited and found to occur only at concentrations causing severe cytotoxicity (≤50% ↓ in mitotic indices). It is likely, therefore, that the increase in chromatid breaks (also suggestive of a cytotoxic effect) is secondary to cytotoxicity, and not indicative of a clastogenic response. No in vivo genetic toxicolo gy assays were available on chloropicrin; this deficiency in the database represents a data gap. Overall, the human health relevance of the reproducible positive Ames test can not be ascertained at this time since the mutation response appears to be rest ricted to bacterial systems and no in

vivo genetic toxicology studies ( e.g. transgenic mouse assay would be ideal, mouse micronucleus assay to satisfy FIFRA guideline requirements) were performed.

B. HEDs Response to the CDPR cancer assessment for Chloropic rin

1) Rationale for lack of concern for carcinogenic potential via the inhalation route

.

HED has performed a statistical analysis of the lung tumors observed in female mice in the chronic mouse inhalation study (43632201) consistent with procedures under

t he Cancer Review Committee (CARC) (Brunsman, 2009; TXR 0055260).Page 10 of 18

Table1. Results of the Fisher’s Exact Test for Lung Tumors Seen in Female CD

- 1 Mice +

.

Tumor Type 0 ppm 0.1 ppm 0.5 ppm 1.0 ppm

Adenomas (%)

p = 13/47

(28)

0.02470* 9/47

(19)

0.88860 17/ 47

(36)

0.25360 19 a

/48

(40)

0.15571

Carcinomas (%)

p = 0/47

(0)

0.1275 4/47

(9)

0.05849 3/47

(6)

0.12097 4 b /48

(8)

0.06112

Combined (%)

p = 13/47

(28)

0.009535** 12 c /47

(26)

0.67943 20/47

(43)

0.09722 22 d

/48 (46)

0.05192

+Number of tumor bea ring animals/Number of animals examined, excluding those that died before

week 40.

a First adenoma observed at week 40, dose 1.0 ppm. ; b First carcinoma observed at week 76, dose 1.0

ppm. ; c One animal in the 0.1 ppm dose group had both an adenoma and a carc inoma.

d One animal in the 1.0 ppm dose group had both an adenoma and a carcinoma.

There is no evidence of carcinogenicity in male mice. The incidences of lung tumors in

female mice are shown in T able 1 . There is a slight increase in adenomas at the high dose (19/48; 40%) compared to the controls (13/47; 28%)

. The incidences for carcinomas showed a flat dose response (i.e, 0, 4, 3, and 4). There is a n increase in the incidences of

adenomas and carcinomas combine d , driven by adenomas, at the high dose (22 /48; 46%) when compared to controls (13/47; 2 8%).

The statistical analyses of the tumor incidences consisted of two

- tailed Fischer’s exact test for pairwise comparisons. A Fisher’s exact test is employed when there are no significant disparities in surviv al between the treated and control groups. The analyses showed no pairwise significance for any of the tumor type ( i.e., adenomas, carcinomas or combined adenomas /carcinomas).

The statistical significance for the positive trends for adenomas (p=0.0247) and combined adenomas and carcinomas (p= 0.05192 ) are not considered to be biologically significant for a common tumor type ( i.e ., lung tumors in mice) since a statistical significance of p<0.05 is required. Similarly, the p=0.05192 obtained in the pairwi se comparison of the

combined adenomas/carcinomas is not considered to be biologically significant for this tumor type since a statistical significance of p<0.01 is required (Lin and Rahman, 1998

, Lin, 2000, Haseman, 1983, 1984 ). It is also noted that the adjusted denominator numbers of female mice (combined adenomas and carcinomas for lungs) in the last row of Table 8Page 11 of 18

(page 31 ) by CDPR is inappropriate for statistical analysis. The result of the statistical analysis performed on these adjusted numbers is therefore an artifact and not appropriate

for use in risk assessment.

HED determined the female mouse lung tumors to be of no concern because: lung adenomas are tumors of relatively common occurrence in mice, they did not show progression to carcinomas, there was a flat dose response for the carcinomas, they did not occur with a reduced latency (average time to tumor was 543 day in the high dose group

vs. 554 days in the controls ), with only an 11 day reduction in average time to lung tumor;

and there was no evidence of carcinogenicity in male mice or male and female rats.

HED concluded that there is no concern for the carcinogenic potential of chloropicrin based on the following weight of evidence considerations: 1) no lung tumors were seen in

male or fem ale rats exposed to the same exposure concentrations for a longer period of time (104 weeks) in the same laboratory; 2) no increase in lung tumors was seen in male mice; and 3) the weak response in female mice ( i.e. , the presence of a single common

tumor that lacked biological or statistical significance with no increase in the proportion of malignant tumors n or decrease in the time to tumor occurrence). The latest risk assessment for chloropicrin demonstrates that c hronic exposure is unlikely but include d a long

- term Human Equivalent Concentration (HEC) of 0.004 ppm

. The HEC of 0.004 ppb is 250

- fold lower than the concentration (1.0 ppm) that induced biologically insignificant lung tumors and would be protective of all chronic effects, including, any
pot ential carcinogenicity from inhalation exposure to chloropicrin.

C. HEDs Comment s to the CDPR Document Dated June 1, 2009

C DPR The CDPR report (Page 29; Line 31) stated that there was a trend for the combined adenomas/carcinomas but no pairwise significan ce by Fisher’s exact test although the p value

was 0.053.

HED Response : Results of the Fischer’s exact test by HED also yielded a comparable pairwise p value of 0.0519 for the combined adenomas/carcinomas.

C DP R : The CDPR report (Page 28; Line 33) stat es that the combined incidence of adenomas/carcinomas was further analyzed using the Poly

- 3 trend test. The Poly

- 3 test resulted in yielding statistical significances for both the trend and pair wise (p=0.021) for the combined

adenomas/carcinomas.

HED Re sponse: There are no issues related to survival in female mice. Survival was comparable among groups (i.e., 29%, 31%, 34%, and 33% at 0, 0.1, 0.5, or 1.0 ppm groups, respectively). The Poly 3 test is used only when survival is a confounding factor. The Poly 3 test adjusts for differences in mortality among treatment groups by modifying the number of animals at risk in

the denominators in the calculations of overall tumor rates.Page 12 of 18

In this chronic inhalation mouse study, there is no concern for time

- to

- tum or appearance since

there are no tumor

- related early deaths which affect survival. Consequently, it is unclear why CDPR elected to employ the Poly 3 test which is used only when survival time is the confounding factor. The National Toxicology Program (NTP ) uses the Poly 3 test to adjust for intercurrent mortality in their animal bioassays. The Poly 3 test was developed based on the

results of extensive time

- to

- tumor appearance data for a variety of tumors in NTP’s carcinogenicity bioassays using studies c onducted with Fischer 344 rats and B6C3F1 (Bailer and Portier, 1988). The chloropicrin study, however, used CD

- 1 mice and therefore, it is not appropriate to “extrapolate” the BC3F1 mice model to a different strain (CD

- 1) which has a different life span. Consequently, it is HED’s position that since survival was not a confounding factor in this study there is no need to use the Poly 3 test and that the Fischer’s exact test is the appropriate test for tumor analyses.

C DP R: The CDPR report (Page 29, 30; l ine 41) states that the average time to tumor was shorter in the high dose females (543 days) compared to controls (554 days) primarily due to two deaths that occurred within the first year, unrelated to treatment.

HED Response: The reduction of 11 days (554 vs 543) in average time to lung tumor is not biologically significant, especially since (as noted by CDPR), the reduction was primarily due to two animals that died early of unrelated causes.

CDPR: The CDPR report (Page 30; line 32

- 38) states that no historical control data were available for the testing laboratory and therefore, historical control data published by Charles

River for this strain for studies conducted between 1987 and 1996 were used instead. These data showed an average incidence of 1 4% (0

- 28%, range) and 8.7% (0

- 27% range) for adenomas in males and females, respectively (Giknis and Clifford, 2000). The incidence of these tumors was above the average for historical control data for all groups and outside historical control range for

mo st groups including the control group of males.

HED Response: The concurrent control group is always the one that is most appropriate and important in testing treatment

- related increase in tumor rates in carcinogenicity studies Due to the large study

- to

- study variations caused by differences in nomenclatures, laboratory, time period, and pathologists it is extremely important that the historical control data chosen should be comparable with the current study. CDPR used the historical control data from Charles River Laboratories which is not appropriate since all of the studies cited were oral (gavage or dietary) studies (i.e., none were inhalation studies). The lung tumor incidences in the current study should be compared to the historical control data of inhalation studies since such a study would require a closer examination of the lung than oral or dietary studies which would result in the diagnosis of more lung tumors.) Even if the Charles River studies are considered, the fact that the concurrent

co ntrol lung tumor rates falls outside the historical control range essentially makes the historical control data useless in rendering a meaningful comparison.

In summary, HED does not concur with the conclusions reached by CPDR and reiterates its

conclusio n that there is no evidence of carcinogenic potential in chloropicrin inhalation studies and that quantification of cancer risk is not required.Page 13 of 18

Bailer, J.A and Portier, J. (1988). Effects of treatment

- induced mortality and tumor

- induced mortality on tes ts for carcinogenicity in small samples. Biometrics 44, 417

- 431.

Giknis, M.L.A and Clifford, C.B. (2000). Spontaneous neoplastic lesions in the Crl:CD

- 1 (ICR) BR Mouse. Charles River Laboratories. March, 2000.

Giller S., Le Curieux F, Gauthier L, Erb F, Marzin D. (1995). Genotoxicity assay of chloral hydrate and chorlopicrine. Mutat Res. 348(4): 147

- 152.

Haseman J.K (1983) A reexamination of false

- positive rates for carcinogenesis studes. Fundamental and Applied Toxicology 3: 334

- 339

Haseman J.K. (19 84) Statistical isssues in the design, analysis and interpretation of animal carcinogenicity studie. Environ. Hlth. Prespective 58: 385

- 393

Haworth S, Lawlor T, Mortelmans K, Speck W, Zeiger E. (1983). Salmonella mutagenicity test

results for 250 chemica ls. Environ Mutagen . 1983;5 Suppl 1:1

- 142.

Lin K.K and Rahman, M. A (1998). Overall false positive rates in tests for linear trend in tumor incidence in animal carcinogencity studies of new drugs. J. Biopharm. Stat. 8(1): 1

- 15.

Lin K. K. (2000) Carcinog enicity studies in pharmaceuticals. In Encyclopedia of Biopharmaceutical Statistics, edited by S.C.Chow, Marcel Dekker, New York, 88

- 103

Schneider, M, Quistad, GB, Casida, JE. (1999). Glutathione activation of chloropicrin in the Salmonella mutagenicity test. Mutat Res. 439: 233

- 238.

USEPA 2005. Guideline for Cancer Risk Assessment. March. EPA/630/P

- 03/001F.Page 14 of 18 

## Attachment B

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDE

AND TOXIC SUBS TANCES

MEMORANDUM

Date: September 10, 2009

SUBJECT: Chloropicrin Qualitative Risk Assessment Based on CD

- 1 Mouse Dietary Study

PC Code: 081501 DP Barcode: D215526

MRID No. : 43632201 Registration No. : NA

Petition No.: NA Regulatory Action: NA Assessment Type: NA Re registration Case No.: NA

TXR No.: 0055260 CAS No.: 76

- 06

- 2

FROM: Lori L. Brunsman, Statistician

Science Information Management Branch Health Effects Division (7509P)

THROUGH: Jessica Kidwell, EPS

and

B renda May, Acting Branch Chief Science Information Management Branch Health Effects Division (7509P)

TO: Elissa Reaves, Toxicologist

Risk Assessment Branch VI Health Effects Division (7509P)

I. CONCLUSIONS

Female mice had statistically signif icant trends for lung adenomas (p < 0.05) and combined lung adenomas and carcinomas (p < 0.01). There were no significant pair

- wise comparisons of the dosed groups with the controls.Page 15 of 18

There was no evidence of survival disparities among dose groups in fem ale mice.

There was no evidence of carcinogenicity in male mi ce.

II. ACTION REQUESTED

Prepare a qualitative risk assessment of the female mouse lung tumors.

III. BACKGROUND

An inhalation oncogencity study in CD

- 1 mice was conducted by Bushy Run Res earch Center, Export, Pennsylvania, for The Chloropicrin Manufacturers Task Force c/o Nicklor Chemical Company, Long Beach, California, and completed April 25, 1995 (Laboratory Project No. 92N1105).

The study design allocated groups of 50 mice to target exposure concentrations (in air) of 0, 0.1, 0.5 or 1.0 ppm of Chloropicrin vapor for 6 hours/day, 5 consecutive days/week for 78 weeks. Doses were equivalent to analyzed mean concentrations of 0, 100, 498 or 988 ppb.

IV. RESULTS/DISCUSSION

Survival Anal yses

There was no evidence of significant differences in mortality with increasing doses of Chloropicrin in female mice (Table 1).

Tumor Analyses

Female mice had statistically significant trends for lung adenomas (p < 0.05) and combined lung adenomas and carcinomas (p < 0.01). There were no significant pair

- wise comparisons of the dosed groups with the controls. The statistical analyses of the tumors in the female mice were based upon Fisher’s Exact Test for pair

- wise comparisons and the Exact Test f or trend (Table 2).Page 16 of 18 Table 1. Chloropicrin

– CD

- 1 Mouse Study (MRID 43632201 )

Female Mortality Rates + and Cox or Generalized K/W Test Results



## Weeks

Dose (ppm) 1

- 26 27

- 52 53

- 82 f Total

0 1/49 a 2/47 a 11/45 14/48

(29)

0.1 1/49 b 2/48 12/46 15/49

(31)

0. 5 0/49 c 1/47 c 15/46 16/47

(34)

1.0 0/49 d 6/48 d 10/42 16/48

(33)

+ Number of animals that died during interval/Number of animals alive at the beginning of the

interval.

f Final sacrifice at weeks 81

- 82.

a Two accidental deaths in the control group, one eac h at weeks 3 and 50.

b One accidental death at week 8, dose 0.1 ppm.

c Three accidental deaths in the 0.5 ppm dose group, one each at weeks 5, 31 and 32.

d Two accidental deaths in the 1.0 ppm dose group, one each at weeks 25 and 42.

( )Percent.

Note: Time intervals were selected for display purposes only.

Significance of trend denoted at control

. Significance of pair

- wise comparison with control denoted at dose level.

If * , then p < 0.05. If ** , then p < 0.01.Page 17 of 18 Table 2. Chloropicrin

– CD

- 1 Mouse St udy (MRID 43632201 )

Female Lung Tumor Rates +

and Fisher’s Exact Test and Exact Test for Trend Results

Dose (ppm)

0 0.1 0.5 1.0

Adenomas (%)

p = 13/47

(28)

0.02470* 9/47

(19)

0.88860 17/47

(36)

0.25360 19 a

/48 (40)

0.15571

Carcinomas (%)

p = 0/47

(0)

0.1275 4/47

(9)

0.05849 3/47

(6)

0.12097 4 b /48

(8)

0.06112

Combined (%)

p = 13/47

(28)

0.009535** 12 c /47

(26)

0.67943 20/47

(43)

0.09722 22 d

/48 (46)

0.05192 +Number of tumor bearing animals/Number of animals examined, excluding those that d ied before

week 40.

a First adenoma observed at week 40, dose 1.0 ppm.

b First carcinoma observed at week 76, dose 1.0 ppm.

c One animal in the 0.1 ppm dose group had both an adenoma and a carcinoma.

d One animal in the 1.0 ppm dose group had both an adenoma and a carcinoma.

Note: Significance of trend denoted at control

.

Significance of pair

- wise comparison with control denoted at dose level.

If * , then p < 0.05. If ** , then p < 0.01.Page 18 of 18

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