Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 1 EPA Reviewer: John Doherty, Ph.D. Reregistration Branch II, Health Effects Division (7509P) EPA Secondary Reviewer: Linda Taylor, Ph.D. Reregistration Branch II, Health Effects Division (7509P)

TXR # 0050308



## Data Evaluation Record

Study Type: Special Non-Guideline Assessment for RBC Cholinesterase in Humans.

DP Barcode : D255538 Submission No.: S561108 PC Code: 059101 Tox Chem. No.: 219AA

Test Material: Dursban R, 

### 99.8% Chlorpyrifos (Lot No.: MM930503-17)

Citations: Kisicki, J.C., Seip, C.W. and Combs, M.L., 1999, “A Rising Dose Toxicology Study to Determine the No-Observable-E ffect-Levels (NOEL) for Erythrocyte Acetylcholinesterase (AChE) Inhibition and Cholinergic Signs and Symptoms of Chlorpyrifos at Three Dose Levels”, MDC Harris Laboratory, Lincoln Nebraska, Study No.: 21438 (for the Harris Project) and DR K-0044793-284 (for DOW AgroSciences), April 19, 1999, MRID No.: 44811002.

Brzak, K.A. "A Rising Dose Toxicology Study to Determine the No-ObservableEffect Levels (NOEL) for Erythrocyte Acetylcholinesterase (AChE) Inhibition and Cholinergic Signs and Symptoms of Chlorpyrifos at Three Dose Levels - Part B (Pharmacokinetic paraoxonase data)". Toxicology and Environmental Research and Consulting, DOW, Study No.: 981176, June 5, 2000. MRID No.: 45144101.

Juberg, D.R. and J.L. Mattsson “Updated DOW AgroSciences Response to EPA Query Regarding Two Toxicology Reports”. DOW AgroSciences LLC, Indianapolis, IN, May 28, 2008, MRID No.: 47436401. Unpublished.

Sponsor: DOW AgroSciences.

Executive Summary: In a special acute oral study (1999, MRID 44811002) performed to assess effects on human red blood cell (RBC) acetylcholinesterase (AChE), chlorpyrifos (99.8%; Lot # MM930503-17) in a gelatin capsule was administered to 6 human subjects/sex / dose group at dose levels of 0 (lactose-filled capsule), 0.5 or 1.0 mg/kg (Phase 1)

. When it was determined that there was no inhibition and no adverse reactions in these subjects, a second phase of 6 human subjects/sex/group were dosed similarly as control and 2.0 mg/kg chlorpyrifos

. The subjects vital signs (blood pressure, pulse, respiration and temperature were evaluated theChlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 2 morning prior to dosing and at 1, 2, 4, 8, 12, 24, 48 and 168 hours post dosing. In addition hematology

, clinical chemistry and urinalysis assessments were performed one week post dose. Blood was assessed at –10 hours, zero (pre-dose), and at 2, 4, 8, 12, 24, 36, 48, 72, 96, 144 and 168 hours post dose for RBC AChE activity. Plasma cholinesterase (ChE) was not assessed. Blood and urine were collected at selected intervals and analyzed for chlorpyrifos, chlorpyrifos oxon, and the principal metabolite 3,5,6- trichloro-2-pyridinol (TCP) to define the pharmacokinetics of chlorpyrifos in humans

. The paraoxonase (PON1) status was determined for each subject. Serum paraoxonase activity was measured against chlorpyrifos oxon, paraoxon, and diazoxon, and called chlorpyrifos oxonase (CPOase), paraoxonase, or diazoxonase, respectively (MRID# 45144101). Additionally, the PON phenotype (i.e. QQ, OR and RR) was determined for each subject. Systemic Effects. There were no apparent clinical reactions or changes in clinical chemistry parameters related to treatment. Pharmacokinetic Data. Chlorpyrifos was detected in the serum of 4 of the 12 subjects (2-8 hours post dose) in the1.0 mg/kg dose (range of 1.1-5.6 ng/g) and in 4 of the 12 subjects (2- 12 hours post dose) in the 2.0 mg/kg dose (range 1.3-18 ng/g). TCP was detected in the blood of all subjects through 120 hours (0.5 and 1.0 mg/kg) and through 168 hours (2.0 mg/kg). The highest concentration of TCP reached range d from 110-380 ng/g (0.5 mg/kg), 140-610 ng/g (1.0 mg/kg), and 370-1600 ng/g (2.0 mg/kg). Chlorpyrif os and chlorpyrifos oxon were not found in the urine at any dose level, and chlorpyrifos oxon was not found in the blood of any subject. Subject #56 (QQ phenotype) the only subject dem onstrating RBC AChE inhibition had a peak concentration of 18 ng/gm chlorpyrifos at 8 hour s following a 2 mg/kg dose, but withdrew from the study after 48 hours for a personal problem. This same subject had the highest levels of serum (6671 ng/gm) and urinary (22.8 mg) TCP accumulated up to 48 hours. The serum chlorpyrifos and serum and urinary TCP data all suggested that this subject absorbed more dose than the other subjects on the study. CPOase for this subject was similar to the other subjects with the phenotype QQ. RBC AChE. Zero time (predosing) baseline RBC AChE ranged from 8143±982 (±12%) to 9572±539 (±6%) U/L for males and 8576±556 (±6%) and 9165±709 (±8%) U/L for females indicating good precision for the baseline data. These RBC AChE values were within the expected range for humans. Only one individual had a decrease in RBC AChE that suggested inhibition by chlorpyrifos as indicated by being consistently decreased at the critical hours post dosing. For this subject (#56, a female dosed with 2 mg/kg), inhibition of RBC ACHE was observed at 8 (23% ↓ ), 12 (maximum 28% ↓ ), 24 (26% ↓ ), 36 (19% ↓ ) and 48 (21% ↓ ) hours post dose. There were no associated cholinergic symptoms reported, although a transient numbness in the upper arms in this subject was reported at about 2 hours post dosing or well before AChE inhibition and significant levels of TCP in the serum were detected. The proposed LOAEL is 2 mg/kg/day for RBC AChE based on 28% inhibition in one female subject. The proposed NOAEL is 1 mg/kg.

Classification: This study is classified as RESERVED. This study has a key deficiency, namely that no assessments of plasma cholinesterase were made. The study is considered a useful assessment for potential RBC AChE inhibition and contains important pharmacokinetic data as well as information on the PON status of the volunteers.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 3 Compliance: No-Data Confidentiality Claims (No claim of confidentiality within the United States), GLP and Quality Assurance Statements were provided. The study was said to be conducted in accordance with all applicable U.S. guidelines as specified in Title 21 of the Code of Federal Regulations parts 50, 556, and 321 and the International Guidelines for Human Testing as promulgated in the Declaration of Helsinki (1964 and as amended 1996).



## Part A. Clinical aspects includi ng AChE Assessments (MRID No.: 44811002).

Experimental Constants

A. Test Materials:

Test Chemical: Chemical: DursbanR - technical name for chlorpyrifos Source: DOW AgroSciences LLC Lot: MM930503-17 Purity: 99.8% (scheduled for decertification in June 2003) Appearance: White crystalline powder CAS # 2921-88-2 Chemical Name: 0,0-diethyl 0-(3,5,6-trichloro-2-pyridinyl) phosphorothioate

Negative Control (placebo): Chemical: Lactose Source: Mallinckrodt N.F. Lot: 6279 KXHA Purity: Not specifically stated but stated to “meets N.F. requirements” CAS # 63-42-3



### B. Human Subjects:

The subjects were recruited from the Lincoln, Nebraska area in response to an advertisement. The criteria for selection for inclusion and continuation in the study were described on pages 102 to106 of the study report.

Some of the characteristics of the participants who were actually dosed with either the control (lactose) or chlorpyrifos are as follows:

Number: 30 males and 30 females. Occupations: Not stated for each individual. Age: Males: 19 to 54 years; Females: 20 to 52 years. Weight: Males: 146 to 224 pounds; Females: 98 to 200. Race: Males: 28 Caucasian, 1 black and 1 Asian; Females: all Caucasian.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 4 Medical Table 4.4 (page 243) presented comments on the medical history of History: each subject. In the opinion of this reviewer, the medical history appeared to be typical of a group of 60 humans within this age bracket. There did not appear to be any medical conditions that would affect the outcome of the study. The only entries for subject #56 were that she was a non-smoker and was hospitalized twice for childbirth (12/93 and 10/97).

Note: Additional tables presented the results of ur inary analysis for drugs (cocaine, ethanol and cannabinoids) taken from samples at screening and "interim". All entries were indicated as being negative. Data were also presented for the results of the pregnancy test and all entries were negative.



### C. Experimental Protocol. The experimental protocol is described in Table 1 below.

Table 1. Experimental Design.

Group Phrase Dose (mg/kg) Subjects Comments

A I 0.5 6 ♂ /6 ♀

B I 1.0 6 ♂ /6 ♀

D(1) I 0 (placebo) 6 ♂ /6 ♀

C II 2.0 6 ♂ /6 ♀

D(2) II 0 (placebo) 6 ♂ /6 ♀ Blood sampled at -10 and 0

, hr pretreatment and at 2, 4, 8, 12, 24, 36, 48, 72, 96, 120 144 and 168 hours post treatment and analyzed for RBC AChE, chlorpyrifos and its metabolites.

Urine, blood pressure, pulse, ECG and body temperature and clinical laboratory assessments were made at pretest and one week after administration of placebo or chlorpyrifos. The subjects were released from the study after 7 days.

Total Subjects = 30 ♂ and 30 ♀

. Phrase I was conducted first and when it was determined that there was no inhibition of RBC AChE and there were no adverse effects, Phrase II was initiated. Phase I groups were dosed on 10/3/98 and Phase II groups were dosed on 10/17/98.



### C. Basis for Dose Level Selection:

The low dose of 0.5 mg/kg was based on a previous study (Nolan, 1984 ; MRID 00124144) in which this dose level produced decreases in plasma ChE by 80% but had no effects on RBC AChE and did not result in clinical signs. This dose was included to provide a NOEL for RBC AChE. The next higher dose of 1 mg/kg was thought to be a dose where noticeable RBC AChE might be expected without showing clin ical signs in the subjects. The higher dose of 2 mg/kg was initiated when it was established that there was no inhibition of RBC AChE at 1 mg/kg in order to reach a level where noticeable inhibition of RBC AChE might be attained. It should be noted here that administration of the chlorpyrifos in this study was in a capsule, whereas chlorpyrifos was applied to a lactose tablet in the Nolan study.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 5 D. Dosing Data Each subject was dosed based on his/her body weight and chlorpyrifos was weighed out to the 0.1 mg and placed in white opaque number zero capsules the day prior to dosing. The capsule was "filled with lactose" and then closed prior to dosing. Data on the actual mg of chlorpyrifos administered to each subject that r eceived the chlorpyrifos were presented in Table 4.27, page 545. This table presents the weight of the capsule, the weight of the capsule plus the chlorpyrifos as well as the weight plus lactose and the subject’s weight to assure that each subject was administered the proper dose in mg/kg. For example, subject #56 had a body weight of 87.7 kg and was dosed with 173 mg of ch lorpyrifos (268 mg weight of capsule plus chlorpyrifos - 95 mg weight of capsule). The dose this person in the 2 mg/kg dose group received was 173 mg/87.7 kg = 1.97 mg/kg.

The subjects arrived at the clinic the day before scheduled dosing and at 8 PM were given a "snack" but fasted for the next 10 hours. The subjects were given a bracelet with a unique bar code to identify specimens collected. Starti ng at approximately 7 AM, each subject was given his/her dose of either lactose only or chlorpyrif os containing capsule. Each subject was watched to assure the capsule was swallowed. Following swallowing, each subject was given 240 mL of water and it was assured by the study team that the capsule was swallowed. The subjects were given their lunch at approximately 11:30 AM a nd dinner at 4:30 PM and then a snack at 8:30 PM. The subjects were kept at the clinic for 48 hours and were required to return to the clinic at 72, 96, 120, 144 and 168 hours after initial dosing. Although the subjects were asked about strenuous activity prior to coming to the clinic, there were no comments on the level of physical activity the subjects were allowed following dose administration. There were restrictions on the consumption of alcohol and tobacco as well as non-prescription and prescription drugs.

In response to several inquiries that HED made regarding why alternates were needed and the fate of some of the subjects, the DOW company responded in a supplemental report (2008, MRID 47436401). This report indicated that alternates were used because some of the originally assigned subjects either were late reporting or reported with various symptoms that the staff determined might affect the study. Of the alternates used there remains one subject (#47) where there is some confusion as to whether or not his dose was correct based on conflicting body weight and dose administered data. It cannot be determined with certainty if this person was dosed at a rate of 1.63 mg/kg or his group dose of 2 mg/kg.

C. Statistics

(Reproduced from the study report page 23-25).

Demographic variables : Descriptive statistics (mean, standard deviation. minimum, maximum, and sample size) were calculated for continuous demographic variables (age, height, and weight) and frequency counts were tabulated for categori cal demographic variables (gender, race, and frame size) by gender, by treatment group, and by phase.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 6 Vital signs: For each phase, descriptive statistics were reported for all vital signs measurements (sitting systolic and diastolic blood pressure, pulse, respiration rate, and temperature) at each time point of collection. If a vital signs measurement was re-tested prior to dosing, the re-test value was used, instead of the original value, to calculate the descriptive statistics. However, if a re-test was required for a post-dose assessment, the original value was used to calculate the descriptive statistics. All collected data were included in the summarization of vital signs assessments. Where individual data points were missing, data were summarized based on reduced denominators.

Signs and symptoms : Signs and symptoms were coded using the 5th Edition of the COSTART Adverse Event dictionary. These data were tabulated by the number of subjects reporting at least one symptom and as percent of number of subjects dosed in each treatment group.

RBC AChE : RBC AChE concentrations were presented by subject and blood collection timepoint and were summarized by treatment group and gender using means and standard deviations. RBC AChE percent of baseline concentration values were presented and summarized in the same way. Percent of baseline at time t was calculated as follows:

Percent of Baseline1 = (AChE* 100)/baseline

where AChE represents the RBC AChE concentrations at time t and that individual’s baseline is the average of the concentrations collected at time -10 and time 0 predose. All collected RBC AChE concentrations were included in the summarization by gender and treatment group. Where individual data points were missing, data were summarized based on reduced denominators. These percent of baseline data were inspected and a depression of 20% or more in any subject’s RBC AChE activity, relative to the baseline and in the absence of a concomitant shift in the RBC AChE activity for the control group, was considered a significant depression. The RBC AChE activity was also normalized for both baseline and for RBC AChE activity for the concurrent control (placebo) group for gender at the time interval. Percent of baseline normalized to concurrent control at time t was calculated as follows:

Normalized Percent of Baseline t 

### = (100*AChEt/baseline) — control t 

### + 100

where AChE and baseline are defined as above and control is the mean percent of baseline response for the control (placebo) group at time t by gender. These data were presented by subject and timepoint and were summarized by treatment group and gender for each timepoint using means and standard deviations.

For the statistical analysis, the normalized data were truncated after 96 hours for Phase 1 and after 48 hours for Phase 2 so that there would be a value for each subject at each time point. Then the truncated normalized data sets from Phase I and Phase 2 were analyzed, separately, using univariate repeated measures analysis of variance (ANOVA) methods and mixed effects modeling to investigate if there were statistical differences attributed to treatment.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 7 A univariate repeated measures ANOVA was performed as a split-plot analysis with the gender by treatment combinations, denoted as group, as the whole plot factor and time as the subplot factor. In this setting, the time and group by time interactions are valid only if the data satisfied the sphericity property, which says measurements at all time points are equally correlated. Since this was not expected to be true, statistical tests were adjusted for the violation of the sphericity assumption using Greenhouse-Geisser and Huynh-Feldt adjustments.

Mixed effects models were also used where gende r and treatment were considered to be fixed factors and time was considered to be a random continuous covariate.

This approach allowed the modeling of the effect of gender and treatment over time in a structured way, providing the opportunity to iden tify significant higher-order trends associated with AChE inhibition. Covariance structures and terms in the mixed effects models were tested using likelihood ratio tests comparing nested models. Covariance structures failing to provide adequate fit and terms not statistically significant at the 0.10 level of significance were excluded from the model. Differences among the treatment by gender combination pairs were tested using contrast statements within the final mixed effects model and were considered statistically significant at the 0.05 level of significance.

All summarization and analyses were conducted us ing SAS. Output from all SAS programs is included in Appendix 3, Supporting Statistical Documents.



## Specific Methods and Results

1. Comments on the Subjects and Their Participation During the Course of the Study.

There were sixty individuals (30 males and 30 females) enrolled in the study that were actually dosed with chlorpyrifos (36 subjects, 18 males and 18 females) or placebo (24 subjects, 12 males and 12 females). Of the 60 original subjects selected, about 14 were replaced by alternates prior to administration of the dose for various reasons. This is not considered to affect the outcome.

Two subjects, one female placebo (#32) and one female dosed with 2 mg/kg (#56) did not complete the study. The former did not return for the day 6, 7 or 8 post dosing assessments and was discontinued as per the SOP. Since this subject was in the placebo group, the dismissal of this subject is less consequential. The female (#56) dosed with 2 mg/kg chlorpyrifos was described as having a personal conflict and did not return on days 4, 5, 6, 7 or 8 for post dosing events. This subject will be discussed in the later sections of this review in more detail.

A third subject (#11), a male dosed with 1 mg/kg did not provide a blood sample at 168 hours since he was out of the area at the time. He returned to the clinic for subsequent follow up investigations (physicals) and was not dismi ssed from the study. This is not considered consequential because 168 hours is well past the expected time of effect of chlorpyrifos.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 8 One subject (#6), a male in the placebo group

, consumed alcohol on post treatment day 6 (equivalent to one Margarita). This is not considered consequential to the interpretation of the study.

Five subjects (#s 35, 43, 49, 50 and 60; mid-dose female, high-dose male, high-dose female, control female, control female, respectively) either failed to provide urine samples for a given interval or did not collect their samples prope rly such as failure to collect or did not collect in the proper container. This is not considered consequential to the assessment of AChE but may be relevant to the pharmacokinetic studies.

2. Clinical Signs and Electrocardiogram

The subjects were instructed to inform the physicians and/or nurses of any signs or symptoms that they experienced. They were also asked if they felt that they received the test material and if they did why. Vital signs included blood pressure, pulse, respiration and body temperature and were assessed on the morning prior to dosing and at 1, 2, 4, 8, 12, 24, 48 and 168 hours post dosing. The observers that examined the subjects classified symptoms as possibly and/or probably related to treatment if a symptom was noted within 48 hours of treatment. Since the observers did not know if a subject actually received chlorpyrifos, some of the subjects receiving the placebo were said to have symptoms possibly or probably related to the test material.

Appendix Table 1 shows the signs that were indicated by the subjects in either the placebo or groups dosed with 0.5, 1 or 2 mg/kg of chlorpyrifos.

Electrocardiograms (ECG) were done on screeni ng and one week after administration of the placebo or chlorpyrifos. Table 4.10 (pages 345 to 351) presented the data for these analyses. All result entries were reported as "normal". There were some subjects with "sinus bradycardia" noted at week one post dosing that was not present in the screen but these occurred in the placebos as often as in the treated subjects. Th ere were no indications of abnormal recordings to indicate that chlorpyrifos affected the heart. The one week interval between the time of test material administration and ECG assessment is considered by this reviewer too long to be meaningful to detect for an acute response to an OP.

The study author asserted that “There we re no differences noted during this study attributed to treatment with regard to signs or symptoms, vital signs or clinical laboratory results”. HED reviewers concur with this conclusion. There is no indication that a symptom in the treated groups was any greater than similar symptoms in the placebo groups. Other signs occurred at times that did not coincide with any indication of inhibition of RBC AChE.

3. Clinical Chemistry, Hematology and Urinalysis.

Clinical chemistry, hematology and urinalysis assessments were made at pretest screening and one week after dose administration. The one week interval following dosing andChlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 9 clinical chemistry, hematology and urinalysis is not considered by this reviewer to be the most appropriate time.

Serum chemistry included: ALT, AST, albumin, alkaline phosphatase, calcium, chloride, cholesterol, creatinine, GGT, glucose, inor ganic phosphorous, LDH, potassium, sodium, total bilirubin, total protein, urea nitrogen and uric acid.

Hematology included: basophils, eosinophils, HCT, Hgb, lymphocytes, monocytes, neutrophils, platelet count, RBC and WBC

Urinalysis included: bacteria, bilirubin, blood, casts, glucose, ketones, leukocyte esterase, nitrite, protein, RBC, specific gravity, urobilinogen, WBC and pH.

Inspection of the data tables (pages 413 to 454) did not indicate that these parameters were affected by chlorpyrifos treatment. It should be noted; however, that subject #56, the only subject showing inhibition of AChE , withdrew from study after 48 hours and did not provide blood or urine samples for clinical chemistry, hematology or urinalysis.

4. AChE Assessments.

Analytical Methods for AChE assessment.

Blood was withdrawn via venipuncture on an arm vein and there were a total of 14 blood specimens collected per subject (if they completed the study). Once drawn, the blood samples were centrifuged for 12 minutes at 3000 rpm and the plasma discarded (except for the prescreening sampling). The erythrocytes were then washed with saline and centrifuged for an additional 12 minutes at 3000 rpm. The saline was discarded and the erythrocytes were washed twice by the same procedure. The resulting erythr ocytes were stored frozen and shipped on dry ice from the clinical facility located in Lincoln, Nebraska to the MDS Clinical Laboratory located in Toronto, Ontario Canada. AChE was assessed by the Ellman method using acetylthiocholine as the substrate. The analysis was made using a Hitachi 917 automated analyzer. Appendix 5 (pages 547 to 573) described in detail the methods for the preparation and assay and mean data for assessment of the RBC AChE by the Laboratory. It was noted that the standard protocol for this assay called for initially centrifuging the whole blood for 30 minutes (see page 552) and not the 12 minutes as indicated for the subject’s samples in this study. This difference is noted but it is not considered to impact the interpretation of the data.

An overview of the results of the RBC AChE assessments is presented in Table 2. Comments on Table 2 are as follows. Additional mean and individual RBC AChE data are in Appendix – 11 in tables A-J.

The mean results for all groups for RBC AChE data are presented in Appendix 1. The mean data for RBC AChE in U/L for the untreated male subjects when assessed at 0 hour rangedChlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 10 from 8143 ± 982 (±12%) to 9572 ± 539 (±6%) for the five different groups. For females the range was 8576 ± 556 (±6%) to 9165 ± 709 (±8%). The highest mean for both males and females was found in Group B scheduled for dosing with 1.0 mg/kg with chlorpyrifos.

The mean values for males and females are within the expected range for human RBC AChE. In general, the analytical aspects of the measurement of RBC AChE are considered appropriate.

Males. No treatment-related effect was observed in RBC AChE activity at any dose level. Column three of Table 2 shows that the mean RBC AChE value for one of the two male placebo groups was 10.2% less than the predosing mean and this difference was noted at 144 hours post dosing. The treated males based on mean data had maximum decreases of -10.7%, - 13.7% for the 0.5, 1.0 and 2.0 mg/kg dose groups respectively when compared to the predosing values. These maximum depressions of the means were at 96 hours post dose

. Since chlorpyrifos is an organophosphate, it would be exp ected that inhibition would start to occur and remain from about 2 hours to over 24 hours. Thus, 96 hours is well past the critical hours for expected initiation of inhibition.

Females. No treatment-related effect was observed in RBC AChE activity at the 0.5 and 1.0 mg/kg dose levels. At 2.0 mg/kg, one (Subject #56) of the six females displayed RBC AChE apparent inhibition (19%-28%) during the 8-48 hour time interval post dose. All other females at this dose level showed no definite inhibition. Among females, the two control groups demonstrated that there was as much as a 9.6% decrease in RBC AChE and maximum difference was again at 96 hours. The treated female groups demonstrated group means of 6.8%, 8.7% and 10% lower activity readings for all subjects (but only 6.2% lower when one subject that did not complete the study is not included) for the 0.5, 1 and 2 mg/kg dose groups

, respectively. Thus, the decreases in the means for all treated groups are near the maximum decrease that was noted in the placebo group but one subject in the high dose appears to show inhibition.

The data from several individual subjects are discussed below.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 11 Table 2. Overview of the results of the RBC AChE assessments.

Group Mean Predosing (Hour 0) U/L Lowest Posttreatment Mean (U/L) Highest Posttreatment Mean (U/L) Lowest % for an individual

D: Control 1 Males

Females 8143±982 (12%) 1



### 8619±861 (10%) 7316±598 -10.2% @ 144 hr 2



### 7795±759 -9.6% @ 96hr 8043±705 +2% @ 12 hr

8817±884 +2.3% @ 8 hr 88.36% @ 144 hr #10 3



### 83.26% @6 hr #34

A: 0.5 m/kg Males

Females 8998±730 (8%)

8612±1160 (13%) 8036±738 -10.7% @ 96 hr

8028±917 -6.8% @ 144 9189±924 +2.1% @ 8 hr

8938±917 +3.8% @ 144 h 82.68% @ 96 hr #9

88.62% @ 36 hr #19

B: 1.0 mg/kg Males

Females 9572±539 (6%)

9165±709 (8%) 8263±399 -13.7% @ 96 hr

8366±499 -8.7% @ 168 hr 9862±865 +2.9% @ 4 hr

9396±517 +2.5% @ 4 hr 75.47% @ 96 hr #11

88.99% @ 144 hr #33

D: Control 2 Males

Females 9171±1112 (12%)

8576±556 (6%) 8999±1020 -2% @ 36 hr

8380±422 -2.2% @ 4 hr 9425±1041 +2.8% @ 72 hr

8941±442 +4.3% @ 72 hr 89.71% @ 144 hr #44

88.40% @ 144 hr #50

C: 2.0 mg/kg Males

Females 8608±896 (10%)

8623±855 (10%) 8584±806 (no difference)

7761±1239 -10% @ 12 hr. 8089±1088 -6.2% @ 12 hr 4 

### 9004±840 +4.6% @ 72 hr

8604±1064 (no difference) 89.97% @ 36 hr #48

71.77% @ 12 hr #56 92.82% @ 12 hr #58 4



### Data are from 5.1.1 and 5.1.2 for Groups A, B, and Control 1 and 9.1.1 and 9.1.2 for Group C and Control 2.

1 

### The number in () is the standard deviation as pe rcent of the mean for the predosing data. 2 

### The percentChlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 12 is the difference between the highest or lowest mean vs. the control at the interval given. 3 

### The individual subject number for the person showing the lowest relative reading for AChE and the interval that this reading was made. 4 

### Since subject 56 did not complete the study, the reading for the second lowest subject is also presented for this group or the m ean for the remaining 5 subjects is presented.



### Indications of RBC AChE Inhibition Based on Individual Responses. Note: Additional data on the phenotype association with RBC AChE are presented in Appendix 11 Tables. A-C.

. Comment. There is an apparent decrease in the activity noted in Phase I for the males and/or females in the placebo, 0.5 and 1 mg/kg dose groups since at hour 96 many of these (placebos included) suddenly have readings lowe r than their previous readings for RBC AChE. There was no explanation for this provided. See Table 5.1.2 on page 60 of the study report. Since hour 96 is well past the time when chlorpyrifos would be expected to start to cause inhibition, the impact of this sudden decrease in activity is not such as to seriously impact the interpretation of the data. This sudden decrease in activity was not noted for Phase II of the study when both placebo and 2 mg/kg chlorpyrifos were tested (see Table 9.1.2 page 79 of the study report).

Males. Refer to Table H in Appendix. Column five of Table 2 shows that for the control group males, one individual demonstrated 11.6% (subject # 10) and another demonstrated 10.3% (subject # 44) less than his predosing value. Among the treated groups , there was a maximum of 17.4% (subject #9), 24.5% (subject #11) and 10% (subject # 48) apparent decrease in RBC AChE for the 0.5, 1.0 and 2.0 mg/kg dose groups, respectively. Since there are subjects in both the 0.5 and 1.0 mg/kg dose groups that have apparent decreases in AChE it can be implied that these individuals may be unusually sensitive to inhibition of AChE by chlorpyrifos. Thus, the following will discuss in more detail the overall response of these individuals throughout the study. Selected other subjects will also be discussed for the reasons given below.

Subject # 9. Group A. (0.5 mg/kg chlorpyrifos treatment). Subject # 9 was a 19 year old Caucasian male 75 inches tall and weighing 210 pounds and was a non-smoker. No clinical signs or abnormalities were noted in this person’s clinical chemistry or ECG assessments. This subject was reported as having intestinal cramps starting at 2 days, 22 hours and 44 minutes post dosing that lasted 15 hours. This subject replied “no” when asked if he had received the test material and not the placebo.

This subject had RBC AChE readings (in U/L) of 8294, 8602, 8437, 8646, 8844, 8723, 8580, 8261, 8107, 8250, 6985 (-19%), 7535 (-12%), 7376 (-14% ) and 7700 (-11%) for the - 10, zero, 2, 4, 8, 12, 24, 36, 48, 72, 96, 120, 144 and 168 hour assessment times respectively. The apparent decrease in RBC AChE did not begin until 96 hours after dosing. It is noted that the cramps did not coincide with the lower AChE levels. It was noted above that there is a problem with the assays after hour 96 (see comment above).

At the onset of this subject ’ s intestinal cramps (~72 hours) , his RBC AChE was at mostChlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 13 3% less than the zero time reading. However, at 96 hours, his RBC AChE was lowest but his cramps had already disappeared by 85-86 hours (see Appendix I).

In conclusion, there is no justification to support that this individual was unusually sensitive to inhibition of RBC AChE. Inhibition would be expected to appear within a few hours (~ 4-8 hours) post dosing and not 96 hours later. There were also no symptomatic expressions indicative of AChE inhibition (i.e. intestinal cramps are not a specific response to a AChE inhibitor and could be due to many things).

Subject #11. Refer to Table F in Appendix. Group B (1.0 mg/kg chlorpyrifos treatment). Subject # 11 was a 45 year old black male 71 inches tall and weighing 191 pounds and smoked one and a half packages of cigarettes a day. This subject did not report for his day 7 examinations or blood sampling. He did not submit urine for the 144 to 156 hour or 156 to 168 hour collection intervals. He returned to the clinic “the following week” for a post physical exam, ECG and laboratory work up. There was no record of how he responded to whether or not he thought he had received the test material rather than the placebo. This subject's clinical laboratory work up for post treatment indicated he was “moderately lipemic”.

On two occasions (refer to page 468 and Appendix 4.21/1) this subject was reported to have a headache. The first occasion began 3 hours and 40 minutes post dosing and lasted for 19 hours. This means the headache started at 11 am on October 3 and lasted until 6 am on October 4. The second occasion began 22 hours and 40 minutes (approximately 6 am on October 4 post dosing and lasted 1 day and 9 hours. [There seems to be a reporting glitch here because the first headache is reported to be resolved at 6:00 and the second headache starts at 6:00 both on October 4, 1998. There may actually be just one headache.]

This subject had RBC AChE readings (in U/L) of 10307, 10098, 9097 (–10%), 10318, 9768 (- 3%), 9779 (-3%), 9977, 9768, 9141 (-10%), 10153, 7700 (-24%), 9185 (–9%), 9218 (–9%) for the -10, zero, 2, 4, 8, 12, 24, 36, 48, 72, 96, 120 and 144 hour assessment times

, respectively (not assessed at 168 hours). Thus, there was considerable variation in this individual’s readings for RBC AChE but they do not fit an expected pa ttern of inhibition by an organophosphate. Since maximum apparent decrease occurred at 96 hours post dosing (again there is a problem with the hour 96 readings) and the reading at 72 hours was 10153 or essentially the same as the predosing zero hour, this subject is not considered to have chlorpyrifos related inhibition of ChE.

It is noted that there was no consistent depression of RBC AChE during this interval when the subject experienced his headache. For example, the readings were -10%, similar, -3%, -3%. -3%, and -3% at 2, 4, 8, 12, 24 and 36 hours respectively.

In conclusion, there is no justification to support that this individual was unusually sensitive to RBC AChE inhibition by chlorpyrifos. The headache that this individual was reported as having did not coincide with decreased levels of RBC AChE and it was not present when AChE was lowest.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 14 Subject #47. Group C (2 mg/kg chlorpyrifos treatment, but this subject may have actually received a dose of 1.66 mg/kg). Subject #47 was a 24 year old Caucasian male 69 inches tall and 184 pounds. He responded "no" to the question about whether or not he thought he received the test material and did not have any obvious symptoms of AChE intoxication. This subject had highest "estimated dose received" (1.130 mg/kg compared with the group mean of 0.59 mg/kg, see Table 16, page 47 of the Pharmacokinetics report) based primarily on plasma and urinary content of TCP. This subject did not have indications of AChE inhibition since there was at best a 5% decrease in activity at 24 hours but the preceding and succeeding assessments were both higher than the baseline.

Subject #48. Refer to Table D in Appendix. Group C (2.0 mg/kg chlorpyrifos treatment). Subject # 48 was a 23 year old Caucasian male 71 inches tall and weighing 162 pounds and smoked 10-14 cigarettes a day. He responded no to the question about whether or not he thought he received the test material. Acco rding to the data table on page 471, this subject did not experience any symptoms during the post dosing phrase.

This subject had RBC AChE readings of 8569, 8206, 8019, 8008, 7887, 7689, 8206, 7546 (-8%), 7832, 8074, 7766, 7766, 7942 and 8184 for the -10, zero, 2, 4, 8, 12, 24, 36, 48, 72, 96, 144 and 168 assessment times respectively. Thus, this subject’s maximum decrease at 36 hours was immediately proceeded by a value actually the same as the zero time assessment and thus does not show a pattern consistent with inhibition by an organophosphate.

Females . Refer to Tables I and J in Appendix. Column five of Table 2 shows that for the control group females, one individual demonstrated 16.7% (subject # 34) and another 11.6% (subject # 50) less than her predosing value. Among the treated groups there was a maximum of 11.4% (subject #19), 11% (subject #33) and 28.2% (subject # 56) apparent decrease in RBC AChE for the 0.5, 1.0 and 2.0 mg/kg dose groups

, respectively. Since the subjects in both the 0.5 and 1.0 mg/kg dose groups did not exceed the placebo group for apparent decreases in AChE , it is not implied that there are individuals in these dose groups that may be unusually sensitive to inhibition of AChE by chlorpyrifos. Subjects # 51 and 56 are discussed as follows.

Subject #51. Phase II Group C female, 2 mg/kg chlorpyrifos. Refer to Table 4 below for AChE data on this subject. This subject sustained a decrease of 5 to 6% RBC AChE over the critical hours of 12, 24, and 36. However, her pretest variation was also near 5%. This subject also had one of the highest levels of TCP in her blood. But the peak level of TCP did not correspond with the lower readings for AChE.

The placebo female group for Phase II was demonstrated to be very stable over the course of the seven days on the study (see last column in Table 4) as indicated by the data from one individual who demonstrated the most vari ation of the six females in the placebo group. Overall, the 5-6% lower reading in subject #51 is noted but not considered to be definite inhibition caused by chlorpyrifos.

Subject # 56. Group C, 2 mg/kg chlorpyrifos. As indicated previously, subject # 56Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 15 dropped out of the study after 48 hours. It was originally reported that “repeated attempts were made to contact this individual were unsu ccessful and no post study medical evaluation was performed” (refer to page 28 of the study report). However, the supplementary report (2008, MRID 47436401) in response to HED’s questions about the fate of this individual asserts “In, 1999, Richard Nolan PhD was a DAS toxicologist th at was the toxicology contact for the Kisicki study. Dr. Joel Mattsson was in 1999 a DAS toxicologist working with Dr. Nolan and was assured that the testing laboratory had contacted subject #56 personally and she reported no problems with the study but had personal reasons for not returning for further evaluations. DAS is not aware of any additional information on subject #56”. There is still ambiguity with regard to statements about this subject regarding the comments in the study report (page 28) where no contact was made and in the supplementary report (page 17) where contact was said to have been made. Overall, failure of this person to have data after 48 hours does not preclude that data on AChE assessment and pharmacokinetics obtained prior to 48 hours are not useful and informative although the lack of data following 48 hours limits the assessment of the total PK picture. The possibility that this subject developed clinical signs in response to treatment cannot be resolved on the basis of available information.

Page 472 of the study report indicates that this subject reported experiencing "numbness of the upper arms" starting 2 hours and 24 minutes after administration of the chlorpyrifos and lasting a total of 42 minutes. On page 510, the table listing the subject's response to the question if they thought they received the test material does not include subject #56.

This subject was the only subject on the st udy that demonstrated apparent RBC AChE inhibition. Table 3 below provides details about th is subject and shows the extent of inhibition at the critical time interval. It is apparent th at this individual's RBC AChE is decreased starting at 8 hours and remaining so until 48 hours when she was last tested.

Table 3. Summary of Subject #56

Parameter Results Comments

Description (a) A 34 year old Caucasian female 72 inches talland weighing 193 pounds and was a nonsmoker. This individual did not report for the day 4, 5, 6, 7 or 8 blood collection (see page 28) or assessment of vital signs and did not provide urine samples after 48 hours. There is nothing obviously different about this subject to suggest an unusual susceptibility to chlorpyrifos. The subject was genotype QQ but about half the persons on the study had this genotype.

Symptoms (b) Subject had a transient "numbness in upper arms" that started to occur 42 minutes after dosing and lasted for 2 hours and 24 min (self resolved without medication). The numbness alone does not seem to be a response to an AChE inhibitor and since this occurred and was resolved by three hours , or before there wasChlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 16 Parameter Results Comments appreciable apparent inhibition of AChE at 8 hours post dosing, the finding is not considered treatment-related.

RBC AChE IU/L (c) 8426 at -10 hours 8910 at 0 hour 8668 predosing mean 8602 (no difference) at 2 hours, 8525 (-2%) at 4 hours, 6688 (-23%) at 8 hours , 6221 (-28%) at 12 hours 6424 (-26%) at 24 hours 7051 (-19%) at 36hours 6882 (-21%) at 48 hours No additional assessments. Subject shows decrease in RBC AChE that can be considered the critical times expected for an OP following an oral administration.

No other subject shows a similar pattern of decrease in activity.

Serum chlorpyrifos (d) 18 ng/gm at 8 hours 2.5 ng/gm at 12 hours All other times - not detected (< 1 ng/gm)

The highest level in all other subjects was only 5.6 in a female (#21) dosed with 1 mg/kg.

Serum TCP (0 to 48 hours) (e) Subject has total of 6671 ng/gm TCP in serum with values of 71, 120, 1600, 1500, 1300, 1100 and 980 ng/gm for the 2, 4, 8, 12, 24, 36 and 48 hour intervals, respectively. Note there was little TCP in blood at 2 to 4 hours or at the time the numbness was noted.



### This is the highest (total ng/gm 

### ) for the group dosed with 2 mg/kg since the range for all others (both sexes) was 1404 (#42) to 5860 (#47) ng/gm for up to 48 hours. Among females, the other five had values of 2910, 5010, 2730, 2560 and 3310 ng/gm.

Urine TCP (corrected for creatinine) (0 to 48 hours) According to Table 14b for the 0-48 hour interval, Subject 56 had a total of 22.8 mg or was highest for the group dosed with 2 mg/kg. The range for the others in this group was 4.8 (#40) to 16.2 (#47) with a mean of 8.4 ± 3 for all individuals excluding #56. The serum chlorpyrifos data and the serum and urine TCP data all indicate that subject # 56 absorbed chlorpyrifos to a greater extent than the other subjects in this study.

Since no assessments were made after 48 hours, the total TCP picture cannot be determined to compare with the other subjects who seemed to have TCP present in the blood at the later times.

Estimated internal dose of 0.640 mg/kg. - from Table 16 The group mean of 0.59 ± 0.21 mg/kg (range The calculation of the total internal dose for subject #56 is limited since no assessments forChlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 17 Parameter Results Comments chlorpyrifos (g) 0.323 (#40) to 1.130 (#47) mg/kg for the group dosed with 2 mg/kg. males 0.61±0.28; females: 0.568±0.12 mg/kg based on collection for 7 days. TCP or parent chlorpyrifos were made after 48 hours.

CPOase (h) Subject has reading of 9278 Units/liter comparing favorably with the group mean of 9523±1517 Units/liter.

Paraoxonase 367 U/L compared to group mean 737±430 U/L There is nothing unusual about the serum activity of CPOase, or diazoxonase. Although her paraoxonase level was much lower than the group mean this should not affect dosing with chlorpyrifos. Subject was described as phenotype "QQ low" which was a typical classification for many (about half) of the subjects in the study.



### (a) Data are from Appendix 4.3, page 242.. (b) Da ta are from Appendix 4.21.1, page 472. (c) Data are from Table 4.13.2, page 407. (d) Data are from Table 5, page 34 of the Pharmacokinetics report. (e) Data are from Table 7, page 36 of the Pharmacokinetic s report. (f) Data are from Table 14b (corrected for creatinine), page 45 of the Pharmacokinetics report. (g) Data are from Table 16, page 47 of the study report. (h) Data are from Table 17, page 50 of the Pharmacokinetics report.

It is noted that in the screening study this individual had a RBC AChE of 7678 U/L. This was listed as a clinical laboratory comment as “not significant in the context of this study”. When compared to the mean for the -10 and zero hour samplings (mean = 8668 U/L), this would be 11% less. This value of 11% less is not as much as the approximately 28% decrease that was noted for this person following treatment with 2 mg/kg chlorpyrifos. Thus, the decrease in AChE after 8 hours is greater than the spontaneous variation for this subject.

This subject has inhibition rather than random decrease in activity since the decrease in activity starts at 8 hours and rises to a peak at 12 hours and then appears to start to decline at 24, 36 and 48 hours. This would be expected for an organophosphate AChE inhibitor. The pattern of decreased activity also correlates with the amount of TCP in the serum as shown in Table 4.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 18 Table 4. Correlation between RBC AChE activity and blood level of TCP in humans dosed with 2 mg/kg chlorpyrifos.

Hour Sub. #56(QQ ♀ )

_ RBC TCP AChE Blood Sub. #47 (QQ ♂ )

_ RBC TCP AChE Blood Sub. #51(OR ♀ )

_ RBC TCP AChE Blood Sub. #48(OR ♂ ) RBC TCP AChE Blood Placebo #44 (OR ♂ ) RBC AChE Placebo #60 (QQ ♀ ) RBC AChE

2 = 71 +2% 580 -2% 420 -4% 180 -1% -3%

4 -2% 120 +2% 640 -1% 580 -5% 250 = -5%

8 -23% 1600 = 790 -2% 1300 -6% 240 -3% +1%

12 -28% 1500 = 910 -6% 690 -8% 260 -6% +2%

24 -26% 1300 -5% 980 -5% 540 -2% 380 -6% -1%

36 -19% 1100 = 960 -5% 750 -10% 460 -4% =

48 -21% 980 -1% 1000 -3% 730 -7% 470 -5% =

72 +4% 690 +1% 600 -4% 300 +1% -3%

96 +2% 460 +4% 420 -7% 210 -4% -3%

120 +7% 320 +6% 150 -7% 140 -4% =

144 +2% 220 -2% 170 -6% 77 -10% -3%

168 Subject did not return for additional sampling.

+7% 150 = 110 -2% 48 = +1%

Net TCP 

### 0 to 48 hrs 6671 0 to 168 hrs - no data 0 to 48 hrs 5860 0 to 168 hrs 7700 0 to 48 hrs 5010 0 to 168 hr s 6410 0 to 48 hrs 2240 0 to 168 hrs 3015 N/A N/A

Definitely shows inhibition correlating with blood level of TCP. Highest levels of TCP do not correlate with ↓ RBC AChE. Sustains a slight decrease at critical times and is thus possibly showing inhibition. Subject has lowest level of blood TCP but seems to sustain a decrease in RBC AChE Shows that activity varies to - 10%. Shows that female RBC AChE is stable.

TCP data are from Table 7 page 36 in MRID No.: 45144101 and are ng/gm. Note: TCP data were not reported for the blood from the placebo group in Table 7 of the study report. RBC AChE data are from Table 9.1.2 page 78 from MRID No.: 44811002 and are the percent decrease (-) or increase (+) in RBC AChE relative to the baseline. The = sign indicatesChlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 19 that the assessment was within ±1% of the baseline.



### Table 4 also presents data on the variation of RBC AChE activity in one other female and two males dosed with 2 mg/kg of chlorpyrifos and the amount of TCP in their blood. In addition, a male and a female from Phase II placebo group are included to show the spontaneous variation of RBC AChE. It is noted that the female (#60) is stable but the male (#44) showed decreases. One other placebo male (Subject #41, data not shown here because if space limitations) also showed what appeared to be sustained decreased activity (4%-7% from 8 hours to 36 hours post dose).

Table 4 indicates that female subject #51 su stains a slight decrease in RBC AChE and also has a high blood level of TCP but not at the critical times of lower AChE readings. Therefore this subject is not considered to show definite evidence of RBC AChE inhibition in response to 2 mg/kg of chlorpyrifos since the level of decrease is too low and not coincident with serum TCP.



## Part B. Pharmacokinetic and Par aoxonase Data (Refer to MRID No.: 45144101).

Part B 1. Pharmacokinetic data.

Note: Additional data including individual subject data on the pharmacokinetics are in Appendix II Tables A-K..

The sixty subjects on this study gave blood samples (5 mL) for the purpose of determination of chlorpyrifos, chlorpyrifos oxon and 3,5,6-trichloro-2-pyridinyl (TCP) at -10 hours prior to dosing, at zero hour prior to dosing and at 2, 4, 8, 12, 24, 36, 48, 72, 96, 120, 144 and 168 hours post dosing. Urine samples from all urine voided (as per the protocol) for the intervals -48 to -36 hours, -36 to -24 hours, -24 to -12 hours, -12 to 0 hours pretreatment and 0 to 6 hours, 6 to 12 hours, 12 to 24 hours, 24 to 36 hours, 36 to 48 hours, 48 to 60 hours, 60 to 72 hours, 72 to 84 hours, 84 to 96 hours, 96 to 108 hours, 108 to 120 hours, 120 to 132 hours, 132 to 144 hours, 144 to 156 hours and 156 to 168 hours post treatment. The blood and urine were analyzed by GC/MS for chlorpyrifos, its oxon analog and TCP and the method of preparation using internal standards was described. TCP was derivitized prior to analysis.

Data were presented that demonstrated the recovery of spiked samples for chlorpyrifos (98.0 to 99.8%), chlorpyrifos oxon (95.4 to 98.0%) and TCP (91.1 to 97.1%) , and the lower limit of detection was about 1 ng/gm of blood fo r chlorpyrifos and its oxon analog but was about 12.1. ng/gm for TCP. Similarly, recoveries of 96 to 104% for these chemicals from urine were demonstrated. Additional data demonstrated the stability of these chemicals in blood and urine stored -20 or -80 ° C for 6 or 10 days.

Blood and urine analysis for chlorpyrifos and chlorpyrifos oxon.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 20 Chlorpyrifos and chlorpyrifos oxon were not found in any of the urine samples from any of the subjects (refer to Table 10 of the study report page 39). Chlorpyrifos oxon was not found in the blood of any subject (refer to Table 6 of the study report page 35).

Chlorpyrifos was found only occasionally in the blood (refer to Table 5 page 34 of the study report). No subjects dosed with 0.5 mg/kg chlorpyrifos were found to have chlorpyrifos in their blood. Subjects #11 (1.0 ng/gm at 2 hours), #14 (2.7 and 1.5 ng/gm at 4 and 8 hours), #21 (5.6 and 2.9 ng/gm at 2 and 4 hours) and #30 (1.1 ng/gm at 8 hours) dosed with 1 mg/kg were noted to have chlorpyrifos in their blood at the assessment times indicated. Subjects #47 (3.1, 1.3, 3.4 and 1.8 ng/gm at 2, 4, 8 and 12 hours), #49 (3.1 and 1.7 ng/gm at 2 and 8 hours), #56 (18.0 and 2.5 ng/gm at 8 and 12 hours) and #59 (2.2, 4.1, 4.1 and 1.5 ng/gm at 2, 4, 8 and 12 hours) dosed with 2 mg/kg were also shown to have chlorpyrifos in their blood. These are very small amounts of chlorpyrifos. The highest level (18 ng/gm) was found in subject #56 at 8 hours. These data suggest a short half-life for parent chlorpyrifos in blood but there does not appear to be sufficient data to establish a firm number for the half-life of chlorpyrifos in the blood.

Blood and urine analysis for the principal metabolite TCP.

TCP was detected in the blood of all subjects dosed with chlorpyrifos. Refer to Appendix Tables. D, E, F, G, and H.

“The percent recovery corrected for dose as urinary TCP” was reported to be for both sexes combined 34.7±19.6%. 30.8±9.9% and 29.5±10.4% for the 0.5, 1 and 2 mg/kg dose groups, respectively. (Refer to Table 16 “Estimation of dose Received by Volunteers”, page 47.)

The extent of absorption is less than the 70% earlier report from Nolan (1984) 1 and this may be attributed to the fact that the chlorpyrifos in this study was administered in a capsule and this would lead to slower absorption. In contrast, in the Nolan study, chlorpyrifos was dissolved in methylene chloride and placed on a 0.5-gram lactose tablet, which was swallowed with 100 mL of water.

The half-life of TCP as indicated by the blood and urine data are shown in Table 5.

Table 5. Half-lives (in hours) based on TCP in the blood and urine.

Dose (mg/kg) Blood a 

### Males Females Combined Urine b



### Males Females Combined 0.5 29.7±7.4 44.5±32.4 37.1±23.7 29.5±8.9 38.6±24.3 34.3±16.1 1.0 27.7±5.6 30.5±7.4 29.1±6.4 20.5±5.9 33.6±7.4 31.0±7.3

1 Nolan, R.J. et al, (1984) Chlorpyrifos: Pharmacoki netics in human volunteers. Toxicol. Appl. Pharmacol. 73 :8-15.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 21 2.0 36.2±5.9 35.2±4.8 35.8±5.6 38.1±6.5 32.8±6.5 35.7±6.7

a. Table 9, page 38. b. Table 15, page 46.

(Note in MRID 45144101) the printing is small and in some places difficult to distinguish 5, 6 and 8. The best read of the number is in Table 5. Since there were only a few and mostly in the standard deviation, these questionable numbers should not impact the interpretation.)



### Additional serum TCP data on selected subjects are presented in Table 4.

Part B. 2. Serum Paraoxonase and chlorpyrifos oxonase (CPOase) Assessment.

A 5 mL blood sample was taken prior to dosing and sent to the laboratory of Dr. Clement Furlong, Department of Medicine and Genetics, University of Washington, Seattle, Washington and assessed for paraoxonase activity using a spectrophotometric assay. Paraoxonase was tested with chlorpyrifos oxon, paraoxon, or diazoxonase. When the test substance was chlorpyrifos oxon, the activity was called CPOase.

Table 17 of the study report presented data for each subject and group means for the subjects dosed in both phase I (October 3, 1998) and II (October 17, 1998). Table 6 summarizes the CPOase data in this study. Paraoxonase (range - ~250 to ~2502 units/L, when paraoxon was the substrate) and diazoxonase (range ~6548 to 22452 units, when diazinon oxon was the substrate) data were also presented but not shown in this review since the subject of the review is chlorpyrifos.

Table 5. CPOase Data

Group CPOase Range Comment

Phase 1 Control 8418±1639 5430 to 10410 56subjects were QQ, 5 were QR. and 1 was RR. were "QQAow" . Both the high and low readings were from OR individuals.

Phase 1 0.5 mg/kg 7965±1536 5412 to 13341 5 were QQ and 7 were QR. The low was from a QQ and the high was from a QR.

Phase 1 1 mg/kg 8463±1386 6599 to 11615 6 were QQ, 5 were QR and 1 was RR. The high value was from a QQ and the low value was also from a QQ.

Phase 2 Control 11357±3097 6904 to 17333 6 were QQ and 5 were QR and one was RR. The high value was from the RR person and the low value was from a QQ

person.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 22 Group CPOase Range Comment

Phase 2 2 mg/kg 9523±1517 7048 to 13018 6 were QQ, 5 were QR and 1 was RR. The high value was from a QR person and the low value was also from a QR

person.

Subject # 56 has a value of 9278 Units/liter 

### and is very close to the group mean and thus does not have an unusual ability to metabolize chlorpyrifos oxon.



## Conclusions, Discussion, Study Deficiencies and Classification.

1. Study author’s conclusions.

The study author (page 10 of the study report) concluded "The NOEL for signs and symptoms in fasted humans following a single oral dose was 2.0 mg chlorpyrifos/kg of body weight. The NOEL for RBC AChE inhibition in human s given a single oral dose of chlorpyrifos was 1.0 mg/kg of body weight. The 2.0 mg ch lorpyrifos/kg of body weight dose level represented a threshold in that it produced greater than 17.3% depression in 1 of 12 volunteers."

2. Reviewer’s conclusion and discussion.

Signs and Symptoms. There was no indication that any of the signs and symptoms that were noted in the subjects dosed with chlorpyrifos were different in either their nature or degree of severity from the signs and symptoms that were noted in the placebo groups. Some reported symptoms in the subjects that were dosed with chlorpyrifos occurred either well before or after the time when chlorpyrifos absorption was maximal or when the blood or urine level of TCP the principal metabolite of chlorpyrifos was at its maximal level. Also, the only subject showing definite inhibition of RBC AChE did not display any symptoms when maximum inhibition of AChE was attained and this subject's only reported sign (“upper arm numbness”) occurred and resolved well before her RBC AChE was shown to be inhibited and before her serum level of TCP reached higher levels. If the "upper arm numbness" was related to some other cause due to chlorpyrifos than inhibition of RBC AChE it would still be expected for the numbness to persist while the absorption of chlorpyrifos increased. Thus, the proposed NOAEL for symptoms is > 2 mg/kg chlorpyrifos.

Pharmacokinetic Data. Based on the pattern of occurrence of TCP, the principal metabolite of chlorpyrifos in the blood and urine, chlorpyrifos is absorbed rather slowly from the gut and requires about 8 to 12 hours for the TCP blood level to reach a maximum. Based on the blood level of TCP, subject # 56 absorbed more chlorpyrifos in the first 48 hours than any otherChlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 23 subject and this subject also had clear evidence of RBC AChE inhibition.

The rate and extent of absorption of chlorpyr ifos in this study was slower and lower than reported in an earlier study (Nolan, 1984), and this was attributed by the study author to be due to the differences in administration. In this study, chlorpyrifos was administered in a capsule but in the earlier study it was administered on top of a lactose pill. The need for the capsule itself to dissolve in the g-I tract may be a factor.

RBC AChE Inhibition. Review of this study identified one subject (#56, a female dosed with 2 mg/kg, with genotype QQ) as demonstrati ng inhibition of RBC AChE. The decreases in RBC AChE were shown to correlate with high levels of TCP in her serum. As much as 28% inhibition was noted at 12 hours post dosing.

A second subject (#51, with genotype OR) was considered as possibly also showing inhibition and also had one of the highest levels of serum TCP for the group dosed with 2 mg/kg. Although this subject had decreases to only 5 to 6% of her predosing mean, this level of decrease was sustained over the critical hours of expected time for an OP to inhibit blood AChE (i.e. 8 to 24 hours). Inspection of the other four females in Phase II indicated that their RBC AChE activity was very stable over the 168-hour post dosing period. Overall, subject #51 is considered to have only very minimum and indefinite inhibition.

None of the males were determined to be showing definite decreases in RBC AChE. It was noted that one subject (# 48, 2 mg/kg gr oup, OR) had decrease of 8% at 12 hours and 10% at 36 hours but two placebo males indicated that variation in RBC AChE activity can also vary to a decrease of 10%. Also subject # 48 had one of the lowest net totals of TCP in his blood for the group receiving 2 mg/kg.

Thus, the proposed NOAEL for RBC AChE inhibition is 1 mg/kg and the LOAEL is 2 mg/kg. Only one female was concluded to have definite inhibition.

CPOase

This study has important data on each person's PON and CPOase. The single person showing inhibition had CPOase similar to other individuals in the group dosed with 2 mg/kg, but this person also had the highest absorption of chlorpyrifos. Thus, the persons ability to absorb chlorpyrifos from the gastro-intestinal tract may be more important than the CPOase status of the individual.

Study Classification.

This study is being classified as RESERVED.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 24 4. Study deficiencies and compromising issues.

-Plasma ChE was not assessed for. This is considered important since other recent studies with humans and OPs include plasma ChE assessment. Also it was reported in the earlier (Nolan, 1984) study with humans that plasma ChE is inhibited at lower doses than RBC AChE by chlorpyrifos. This deficiency is considered a potentially serious omission.

-The only subject that showed definite i nhibition of RBC AChE did not complete the study after the 48th hour assessments. This subject did not provide blood samples for hematology or clinical chemistry at the scheduled one-week post treatment time. The supplementary report (2008, MRID 47436401) indicated that this person was contacted via telephone and did not report adverse effects and that she had to leave the study for personal

reasons.

-The hematology, clinical chemistry, urinalysis and ECG assessments were made one week following the administration of chlorpyrifos. This is considered a poor design. These assessments should have been done during the time of peak effect of chlorpyrifos on AChE. The assessments after one week are of little value since the chlorpyrifos has been cleared from the body and it would be expected that inhibition of AChE would have been partially reversed by this time or that the body adapted to the decreased AChE activity.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 25 Appendix I - Individual Subject Analysis for subj ects showing symptoms or variation in AChE

Subject # Symptoms or Events (a) RBC AChE Comments HED’s Conclusion

Placebo-Males

2 (no) Increased appetite, headache ( moderate)- vomited. Starting 47 hrs postdosing, lasting for 4 days, 6 hrs. Possibly related to treatment. "One can coca-cola next day". Maximum decrease 12% @ 48 hrs. Other values are 89% to 105%. of predose

8 (yes) Headache (mild)- Starting 10 hrs postdosing, lasting ~13 hrs. Possibly related to treatment. Maximum decrease 9% @ 48 hrs. Other values are 94% to 103%.

10 (yes) No symptoms or events. Maximum decrease 14% @ 96 hrs. Other values are 88% to 103%.

13 (yes) No symptoms or events. Maximum decrease 12% @ -10 hrs. Other values are 97% to 112%.

37 (yes) Dizzy, feels weak, nausea, vomited, body aches - Starting 2 days, 18 hrs lasting (some symptoms) for up to 2 days 11 hrs. Possibly related to

treatment. Maximum decrease 3% @ 96 hrs. Other values 97% to 107% of predose.

41 (no) Itching of insect bite. Starting 2 days 5 hrs, lasting 11 hrs. Unrelated to treatment. Maximum decrease 7% @ 24 hrs. Other values 95% ti 107% of predose.

45 (no) Nausea, vomited. Starting 2 days. Lasting ~20 min. Possibly related

to treatment. No decreases. Values are 100 to 110% of the predose.

46 (no) Headache (mild). Starting ~ 3 hrs. Lasting ~ 3hrs. Possibly related to

treatment. Maximum decrease 6% @ 2 hrs. Other values 98% to 108% of predose. Since these subjects are in the placebo group, there symptoms or events cannot be due to chlorpyrifos treatment.

3/12 subjects have headaches. 4/12 thought they received the chlorpyrifos when it was not given. As much as a 14% decrease in RBC AChE can occur with in the untreated group over the 7 day period.

Placebo-Females

20 (yes) No symptoms or events. Maximum decrease 7% at -10 hrs. Other values 94% to 107%. Since these subjects are in the placebo group,Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 26 Subject # Symptoms or Events (a) RBC AChE Comments HED’s Conclusion

23 (yes) No symptoms or events. Maximum decrease 7% at 144 hrs. Other values 96 to 110%.

29 (no) “hiccough”, heartburn. Starting 11 hrs, lasting 11 hrs. Unrelated to

treatment. Maximum decrease 13% at 96 hrs. Other values 95 to 107%.

32 (no) No symptoms. Maximum decrease 17% and sustains from 96 to 144 hrs. Other values 85 to 105%. Subject included to show variation in AChE.

50 (no) Headache (mild)- Starting 1 day 21 hrs. lasting 3 hrs. Unlikely related

to treatment. Maximum decrease 12% at144 hrs. Other values 97 to 108% of predose.

52 (yes) Headache (mild), loose stool, nausea, intestinal cramps, vomited. Starting on days 3 and 4, lasting 6- 10 hrs (some symptoms). Possibly related to treatment. Maximum decrease 7% at 24 hrs. Other values 97 to 103% of predose.

54 (no) Headache (moderate and mild), nausea. Starting 4-5 hrs, and again at 11 hrs. Lasting 6-7 hrs and 17 hours. Possibly related to

treatment. Maximum decrease 4% at 36 hrs. Other values 97 to 107% of predose.

60 (yes) lack of appetite, headache (mild), nausea. Starting at 3-5 hrs or 13 hours. Lasting 5 to 17 hrs. Possibly related to treatment. Maximum decrease 5% at 4 hrs. Other values 97 to 102% of predose. there reactions cannot be due to chlorpyrifos

treatment.

4/12 (33%) females had headaches. 4/12 thought they received the chlorpyrifos when it was not given. As much as 17% reduction in RBC AChE can be a ttained in the untreated female group.

0.5 mg/kg Chlorpyrifos-Males

3 (no) Increased appetite. Starting 1 day and 23 hrs. Lasting 4 days. Unlikely related to treatment. Maximum decrease 15% at 48 hrs. Other values 94 to 102% of predose. Increased appetite is not an expected response to an OP. Not related to treatment Maximum decrease not supported by earlier or later decreases.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 27 Subject # Symptoms or Events (a) RBC AChE Comments HED’s Conclusion

5 (yes) Subject implied excessive salivation was why he thought he received the test material but there were no indications of excessive salivation listed in the events Table. Maximum decrease 8% at 96 hours. Other values 90 to 108%. No support from either the symptoms or AChE data to for subjects "yes" response.

9 (no) Intestinal cramps. Starting 2 days 22 hours. Lasting 15 hrs. Unlikely related to treatment. Maximum decrease 17% at 96 hrs followed by 11%, 13% and 9% at 120, 144 and 168 hours. Other values Other values were 87% to 105% of predose. Not related to treatment since onset did not coincide with AChE ↓

.

None have headaches. 1/6 thought they received the chlorpyrifos. Note hour 96 had largest decrease in RBC AChE for all but one subject in this group suggesting some assay problem. Since it is hour 96, this should not confound the interpretation of the data.

0.5 mg/kg Chlorpyrifos-Females

26 (no) Nausea. Starting at 1 hr. Lasting 90 min. Probably related to treatment. Maximum decrease 8% at 96, 144 and 168 hrs. Other values are 93% to 104%. An initial localized nausea may result from an OP administration in a capsule without concomitant ↓ in AChE. Maximum ↓ in AChE does not coincide with symptoms. Not considered a definite response to chlorpyrifos.

31 (no) Headache (moderate). Starting 1 day and 3 hrs. Lasting ~2 hrs. Unlikely related to treatment

. Maximum decrease 14% at 96 hrs. Other values were 90% to 104% of predose. Onset of headache does not coincide with maximum ↓ in AChE occurring much later. Not related to

treatment.

36 (yes) Headache (mild), lightheaded, headache (mild). Starting 1 hr or 6 hrs. Lasting ~2 hrs or ~11 hrs. Possibly related to treatment

. Maximum decrease 9% at 4 and 96 hrs. Other values were 92% to 106%. Onset of headaches did not coincide with maximum ↓ in AChE.

2/6 (33%) females had headaches. 1/6 thought they received the chlorpyrifos. Maximum decrease in RBC AChE does not exceed the placebo group.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 28 Subject # Symptoms or Events (a) RBC AChE Comments HED’s Conclusion 1.0 mg/kg chlorpyrifos-Males

1 (yes) Increased appetite. Starting 1 day and 23 hrs. Lasting 4 days six hrs. Unlikely related to treatment. Maximum decrease 7% @ 48 hrs. Other values are 95% to 113% of predose. Symptom not expected of an OP exposure and does not coincide with maximum ↓ AChE.

4 (yes) Loose stool. Starting 2 days and 15- 20 hrs and again on day 4 and 12 hrs. Lasting 1 min. Unlikely related to treatment. Maximum decrease 15% @ 96 hrs followed by deceases of 8%, 12% and 8% at 120, 144 and 168 hrs. Other values 90% to 107%. Symptoms do not coincide with maximum ↓ in AChE.

7 (yes) No symptoms or events. 

### Maximum decrease 16% at 96 hours. Other values are 91% to 116%. No support for subjects "yes" response.

11 not listed Headache (moderate and mild). Starting ~3 hrs and again at ~ 23 hrs. Lasting ~ 19 hrs and 1 day 9 hrs. Possibly related to treatment. Maximum decrease 25% @ 96 hrs. Other values were 89% (at 2 hrs) to 101% (at 4 hrs) of predose. First headache may be associated with ~11% ↓ in AChE. Second headache not associated with ↓

AChE or maximum decrease.

14 (yes) Queasy stomach. Starting 24 min. Lasting 10 min. Possibly related to treatment. Maximum decrease 15% @ 144 hrs. Other values 88% to 99% of predose. An initial unsettled (queasy) stomach may result from the capsule. Symptom does not coincide with ↓ AChE.

1/6 has a headache. This is less than the placebo group and there is no indication that this subjects headache

was more severe. 4/6 thought they received the chlorpyrifos. The maximum decrease in this group was in an individual at 96 hrs postdosing.

1.0 mg/kg Chlorpyrifos-Females

24 (no) Lost voice. Starting ~ 18 hrs. Lasting 8 hrs. Maximum decrease 11% @ 168 hrs. Other values 95% to 105% of predose. Lost voice not an expected response to an OP. Symptom does not coincide with ↓

AChE. Not related to

treatment.

25 (yes) Tired. Starting ~4 hrs. Lasting 1 hrs. Possibly related to treatment. Maximum decrease 9% @ 96 and 120 hrs. Other values 92% to 102%. Symptom does not coincide with maximum ↓ ACHE.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 29 Subject # Symptoms or Events (a) RBC AChE Comments HED’s Conclusion

Not related to

treatment.

30 (no) Headache (mild), tired and repeated headaches (mild). Starting 22 min, ~ 2hrs, ~ 10 hrs and ~ 23 hrs. lasting. Up to 8 days and 7 hrs. Possibly related to treatment. Maximum decrease 8% @ 96 hrs. Other values 95% to 109% of predose/ Onset and duration of symptoms so not coincide with ↓ AChE.

33 (no) Headache (mild). Staring ~ 2hrs. Lasting 4 hrs. Possibly related to

treatment. Maximum decrease 11% @ 144 hrs. Values from 96 hrs to 168 hrs were 89% to 955. Other values were 97% to 111%. Onset of symptom does not coincide with maximum of any ↓ in AChE.

35 (no) Back stiffness. Starting 22 min. Lasting ~4 hrs. Unlikely related to treatment. Maximum decrease 6% @ 168 hrs. Other values 94% to 115%. Symptom not an expected response to OP treatment and does not coincide with maximum ↓ AChE. Not related to

treatment.

2/6 (33%) females had headaches. 1/6 thought they received the chlorpyrifos. Maximum decrease does nor exceed placebo group for RBC AChE.

2.0 mg/kg Chlorpyrifos-Males

40 (yes) No symptoms or events. 

### Maximum decrease 2% at 48 hrs. Other values 99% to 103%. No support for subjects "yes" response.

47 (no) Cut on chin. Starting 2 days. Lasting 6 days. Unrelated to

treatment. Maximum decrease 5% at 24 hrs. Other values 98% to 107% of predose. Not related to

treatment.

None have headache. 1/6 thought they received the chlorpyrifos. Maximum decrease in group was to 10% for one subject (#48 at 36 hours) and dose not exceed the placebo.

2.0 mg/kg Chlorpyrifos-Females

51 (yes) Headache (mild - moderate). Starting at 47 min and again at 3 hrs 7 min and lasting 2-7 hrs. Possibly/probably related to

treatment . One can coca-cola. Maximum decease 6% at 12 hrs. Other values were 95 to 105% of the predose. Onset of headache does not coincide with AChE ↓ . Not related to

treatment.

55 (no) Headache (mild). Starting 3 hrs, lasting 19 hrs. Possibly related to Maximum decrease 5% at 120 hrs. Other values were 97 to Onset of headache does not coincide withChlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 30 Subject # Symptoms or Events (a) RBC AChE Comments HED’s Conclusion

treatment. 107% of predose. AChE ↓

.

56 not listed Numbness in upper arms. Starting 42 min. Lasting 2 hrs and 24 min. Possibly related to treatment. Maximum decrease 28% at 12 hrs. ↓ starts at 8 hours (23% ↓ ), See special discussion. Numbness does not coincide with AChE ↓

.

58 (yes) No symptoms or events. 

### Maximum decrease 7% at 12 hrs. Other values are 96% to 101% No support for subjects "yes" response.

59 (yes) Tired, headache (mild), chest tightness, shortness of breath, headache . Starting ~ 2hrs, and 10 hrs. Lasting 3-13 hrs. Possibly related to treatment. Maximum decrease 7% at 12 hrs. Other values were 95% to 104% of predose. First headache does not coincide with ↓ AChE, the onset of the second headache is two hours before maximum ↓ in AChE but ↓ is only 7%. HED does not conclude that the headache is treatment related.

3/6 (50%) females had headaches. Severity of headach e not greater than placebo subjects and onset does not coincide with AChE decrease. 3/6 thought they received the chlorpyrifos. One subject has definite inhibition of RBC AChE based on sustained decrease at critical times. 

### (a) Only those subjects having reports of symptoms, "events" or responded "yes" (column 1) to the question if they thought they received the test material are listed. Symptom data are from Appendix 4. Under symptoms, the entry in italics refers to the study author’s conclusion regarding whether or not the symptom was related to treatment was made before the subjects were identified as to their dose group. AChE data are from Table 5.1.2 for phase I and Table 9.1.2 for Phase II.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 31 

# Appendix II - List of Tables*

Table A. Mean RBC Cholinesterase Activity (for all groups and all times).

Table B. Serum Paraoxonase/CPOase and 0-hour RBC AChE Activity and Phenotype for dosed

groups.

Table C. Serum Paraoxonase/CPOase and 0-hour RBC AChE Activity and Phenotype for control groups.

Table D. Male RBC AChE Activity, Blood TCP Level and CP Level for the Group Dosed with 2 mg/kg.

Table E. Female RBC AChE Activity, Blood TCP Level and CP Level for the Group Dosed with 2 mg/kg.

Table F. Male RBC AChE Activity, Blood TCP Level and CP Level for the Group Dosed with 1 mg/kg.

Table G. Female RBC AChE Activity, Blood TCP Level and CP Level for the Group Dosed with 1 mg/kg.

Table H. Male and Female RBC AChE Activity and Blood TCP Level for the Group Dosed with 0.5 mg/kg.

Table I. Individual Male and Female RBC AChE Activity (Phase I Control).

Table J. Individual Male and Female RBC AChE Activity (Phase 2 control)

Table K. Individual Male and Female Urinary TCP levels.

* Tables were prepared by Dr. L. Taylor, HED.Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 32 Table A. Mean RBC Cholinesterase Activity (U/L; mean ± s.d.) Time/Dose (mg/kg) 0 A 0 B 0.5 A 1.0 A 2.0 B

Males -10 7520±733 9292±1130 8758±706 9317±790 8802±753 0 8143±982 9171±1112 8998±730 9572±539 8608±896 2 8023±795 9282±1026 9145±714 9568±427 8675±844 4 7948±756 9145±1066 9046±623 9862±865 8642±924 8 8008±645 9189±1101 9189±924 9524±352 8613±872 12 8043±705 9198±1003 8848±663 9543±678 8584±806 24 8036±815 9051±852 9046±817 9599±637 8637±878 36 7674±556 8999±1020 8716±821 9295±626 8663±937 48 7505±845 9042±904 8246±896 8694±669 8567±881 72 7920±838 9425±1041 8974±810 9623±652 9004±840 96 7421±745 9209±849 8036±738 8263±399 8815±868 120 7536±694 9337±765 8571±691 8939±255 8807±904 144 7316±598 9302±800 8764±837 8714±418 8857±907 168 7770±734 9304±994 8527±764 8600±470 8793±562 Females -10 8488±829 8485±373 8804±1068 8833±597 8503±939 0 8619±861 8576±556 8612±1160 9165±709 8523±855 2 8611±915 8444±494 8666±1194 9095±366 8395±855 4 8762±902 8380±422 8412±1368 9396±517 8557±1181 8 8817±884 8716±535 8547±1010 9060±528 8230±1274 12 8404±696 8589±499 8334±917 8886±400 7761±1239 24 8503±900 8510±667 8434±857 9053±241 8092±1191 36 8089±829 8399±476 8244±1015 8617±379 8166±1100 48 8349±735 8545±496 8459±1068 8895±641 8057±1202 72 8551±583 8941±442 8938±1083 9181±477 8604±1064 96 7795±759 8620±537 8147±1213 8508±791 8551±812 120 8092±721 8712±507 8301±857 8466±612 8591±682 144 8144±872 8428±727 8028±917 8462±714 8526±1111 168 8036±876 8549±571 8198±910 8366±499 8419±814 Data from Tables 5.1.1 (pages 55-57) and 9.1.1 (pages 76-77) of MRID 44811002; A Phase 1; B Phase 2Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 33 Table B. Serum Paraoxonase/CPOase and 0- hour RBC AChE Activity and Phenotype #/phenotype CPOase (U/L) Paraoxonase (U/L) RBC AChE (U/L) 0.5 mg/kg [range] 3M (OR) 6850 706 8613 5M (QQ) 8666 317 7942 9M (QQ) 10446 417 8602 12M (QQ) 5412 250 9471 15M (OR) 6871 745 9889 18M (OR) 5412 562 9471 7276±1963 (male) 500±204 (male) 8998±730 (male) 19F (OR) 8073 595 7282 22F (OR) 6994 717 9218 26F (QQ) 8954 373 8602 28F (OR) 8091 895 9900 31F (QQ) 6671 261 9515 36F (OR) 13341 1346 7156 8687±2424 (female) 698±391 (female) 8612±1160 (female ) mean±s.d. 7965±1536 (both) 599±315 (both) 1.0 mg/kg [range] 1M (QQ) 6599 317 9108 4M (RR) 8505 1479 9669 7M (OR) 9008 984 9713 11M (QQ) 7785 361 10098 14M (QQ) 8774 367 10087 16M (OR) 8325 834 8756 8166±874 (male) 724±464 (male) 9572±539 (male) 21F (QQ) 11615 467 9900 24F (QQ) 7534 295 9757 25F (QQ) 7426 339 9548 30F (OR) 10141 923 9130 33F (OR) 8019 1040 8140 35F (OR) 7821 756 8514 8754±1719 (female) 637±314 (female) 9165±709 (female) mean±s.d. 8463±1386 (both) 680±380 (both) 2.0 mg/kg [range] 38M (OR) 13018 1234 8283 40M (QQ) 8918 345 10021 42M (OR) 7048 890 9372 43M (OR) 9134 801 8118 47M (QQ) 10213 456 7645 48M (OR) 8199 823 8206 9422±2051 (male) 758±320 (male) 8608±896 (male) 49F (QQ) 9997 367 7766 51F (OR) 10716 1234 7942 55F (RR) 9422 1590 10076 56F (QQ) 9278 367 8910 58F (QQ) 10141 389 8195 59F (QQ) 8199 345 8250 9626±871 (female) 715±551 (female) 8523±855 (female) mean±s.d. 9523±1517 (both) 737±430 (both)

pages 48-50, 55-57, and 76-77 (MRID 45144101); QQ (low); OR (mid); RR (high)Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 34 Table C. Serum Paraoxonase/CPOase and 0-hour RBC AChE Activity (control) and Phenotype Subject # CPOase (units/L) Paraoxonase (units/L) RBC AChE (U/L) Control [range] 2M (RR) 9565 1668 9196 6M (OR) 5430 645 8921 8M (OR) 6329 728 6809 10M (OR) 9350 882 7821 13M (QQ) 7678 317 8833 17M (QQ) 8001 311 7277 mean±s.d. 7726±1632 (male) 558±500 (male) 8143±982 (male) 20F (QQ) 10015 411A 8239 23F (QQ) 6329 284 8723 27F (QQ) 8217 350 10208 29F (OR) 9871 834 7865 32F (QQ) 9817 434 8723 34F (OR) 10410 1207 7953 mean±s.d. 9110±1556 (female) 586±360 (female) 8619±861 (female) mean±s.d. 8418±1639 (both) 673±425 (both) Control [range] 37M (OR) 9997 1001 9361 39M (QQ) 15894 567 8569 41M (QQ) 9206 378 9592 44M (OR) 9709 1045 10835 45M (OR) 11723 1112 7486 46M (OR) 11363 1134 9185 mean±s.d. 11315±2445 (male) 872±319 (male) 9171±1112 (male) 50F (QQ) 10141 423 8492 52F (QQ) 10069 456 7744 53F (OR) 14096 1134 8261 54F (QQ) 6904 289 8602 57F (RR) 17333 2502 9086 60F (QQ) 9853 367 9273 mean±s.d. 11400±3700 (female) 862±860 (female) 8576±556 (female) mean±s.d. 11357±3097 (both) 867±618 (both) Pages 57 and 77 (MRID 44811002); QQ (low); OR (mid); RR (high)Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 35 Table D. Male RBC AChE Activity, Blood TCP Level, and CP Level (2.0 mg/kg) Subject # 38 40 42 43 47 48

Hour AChE (U/L) -10 0 2 4 8 12 24 36 48 72 96 120 144 168 9141 8283 8437 8360 9097 8800 8877 8998 8481 9372 8976 9108 8844 8734 9680 10021 9922 10109 9856 9768 9790 9889 9636 9966 9966 10021 9955 9691 9493 9372 9537 9471 9152 9130 9350 9405 9658 9834 9648 9592 9911 9174 8041 8118 8206 7964 7942 8327 8228 8437 8129 8668 8690 8052 8569 8668 7887 7645 7931 7942 7744 7788 7370 7700 7667 8107 7942 8305 7920 8305 8569 8206 8019 8008 7887 7689 8206 7546 7832 8074 7766 7766 7942 8184 Chlorpyrifos concentrations (ng/g) in blood samples 0 2 4 8 12 24 36 48 72 96 120 144 168 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 3.1 1.3 3.4 1.8 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TCP concentrations (ng/ g) in blood samples 0 2 4 8 12 24 36 48 72 96 120 144 168 ND 420 560 510 440 430 500 530 1100 290 160 85 41 ND 61 220 320 340 340 360 410 270 170 120 75 98 ND 44 130 230 270

ns 360 370 320 220 160 96 220 ND 230 340 330 410 520 610 610 320 190 90 66 40 ND 580 640 790 910 980 960 1000 690 460 320 220 150 ND 180 250 240 260 380 460 470 300 210 140 77 48 Data from Tables 5 and 7 (pages 34 and 36) of MRID 45144101; ns no sample; value not usedChlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 36 Table E. Female RBC AChE Activity, Blood TCP Level and CP Level (2 mg/kg) Subject # 49 51 55 56 58 59

hours AChE (U/L)

-10 0 2 4 8 12 24 36 48 72 96 120 144 168 7832 7766 7700 7662 8008 7513 8008 8710 7568 7920 7986 8019 7931 8327 8283 7942 7931 7997 7986 7640 7722 7700 7876 8195 8415 8569 7975 8074 10373 10076 10032 10901 10582 10032 10131 10274 10395 10461 9933 9757 10472 9845 8426 8910 8602 8525 6688 (25) 6221 (30) 6424 (28) 7051 (21) 6892 (23) X X X X X 8041 8195 8041 8096 7931 7535 (8)

8107 8107 7821 8503 7931 8228 7832 7876 8063 8250 8063 8162 8184 7623 (8)

8162 8052 7788 7942 8492 8382 8415 7975 Chlorpyrifos concentrations (ng/g) in blood samples 0 2 4 8 12 24 36 48 72 96 120 144 0168 ND 3.1

xx 1.7 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 18.0 2.5 ND ND ND X X X X X ND ND ND ND ND ND ND ND ND ND ND ND ND ND 2.2 4.1 4.1 1.5 ND ND ND ND ND ND ND ND TCP concentrations (ng/ g) in blood samples 0 2 4 8 12 24 36 48 72 96 120 144 168 ND 290 450 490 440 470 430 360 200 130 84 52 35 ND 420 580 1300 690 540 750 730 600 420 150 170 110 ND 290 220 520 500 600 600 530 340 210 120 73 45 ND 71 120 1600 1500 1300 1100 980 X X X X X ND 240 310 480 340 400 430 360 190 110 65 37 24 ND 250 470 610 610 500 480 390 220 110 58 32 23 Data from Tables 5 and 7 (pages 34 and 36) of MRID 45144101; (% inhibition from 0 hour); xx sample not analyzed; X subject left studyChlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 37 Table F. Male RBC AChE Activity, Blood TCP Level and CP Level (1.0 mg/kg) Subject # 1 4 7 11 14 16 AChE (U/L) -10 0 2 4 8 12 24 36 48 72 96 120 144 168 8272 9108 9625 9823 9284 9042 9306 9119 8074 9295 8283 9218 8833 8228 9416 9669 9438 9405 9361 10219 10219 9702 8624 10164 8151 8723 8426 8734 9603 9713 10230 11198 9834 10109 9966 9746 9196 9801 8096 8800 9141 9174 10307 10098 9097 10318 9768 9779 9977 9768 9141 10153 7700 ( ↓ 24) 9185 9218

- 9823 10087 9845 9801 9878 9658 9658 9295 9174 9867 8899 9086 8492 8844 8481 8756 9174 8624 9020 8448 8470 8140 7953 8459 8448 8624 8173 8019 Chlorpyrifos concentrations (ng/g) in blood samples 0 2 4 8 12 24 36 48 72 96 120 144 168 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND Ns 1.0 ND ND ND ND ND ND ND ND ND ND Ns ND ND 2.7 1.5 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TCP concentrations (ng/ g) in blood samples 0 2 4 8 12 24 36 48 72 96 120 144 168 ND 140 280 340 340 440 430 310 160 84 41 18 11 ND 49 130 290 300 250 240 230 160 98 54 34 20 ND 370 430 440 350 270 160 140 54 23 10 ND ND ND 260 450 400 340 270 200 160 75 36 20 ND Ns ND 170 570 610 540 520 440 420 280 220 150 84 50 ND 150 200 170 170 200 280 300 210 130 84 48 29 Data from page 56 of 578 and Tables 5 and 7 (p ages 34 and 36) of MRID 45144101; ns no sample;Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 38 \\ Table G. Female RBC AChE Activity, Blood TCP Level and CP Level (1.0 mg/kg)

Subject # 21 24 25 30 33 35 AChE (U/L) -10 0 2 4 8 12 24 36 48 72 96 120 144 168 9416 9900 9460 10087 9394 9361 9317 8789 9361 9064 8637 8954 8932 8624 9295 9757 9460 9999 9570 9350 9097 9218 9604 9240 8844 9086 9207 8525 9031 9548 9240 9152 9427 8855 9339 8624 9174 9460 8437 8426 8580 8855 9064 9130 8932 9229 9119 8822 8943 8536 8998 9900 8349 8855 8613 8712 7942 8140 8965 8866 8624 8470 8877 8074 7766 8503 7178 7601 7156 7678 8250 8514 8514 9042 8228 8459 8745 8459 8569 8921 9603 7876 8283 7799 Chlorpyrifos concentrations (ng/g) in blood samples 0 2 4 8 12 24 36 48 72 96 120 144 168 ND 5.6 2.9 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 1.1 ND ND ND ND ND ND ND ND ND ND ND 2ND 1ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TCP concentrations (ng/ g) in blood samples 0 2 4 8 12 24 36 48 72 96 120 144 168 ND 220 350 310 300 300 290 280 140 75 43 22 13 ND 96 430 340 310 320 320 300 250 180 120 73 47 ND 160 180 190 190 220 200 160 85 30 16 ND ND ND 10 160 310 290 290 280 280 240 160 85 45 23 ND 32 93 100 110 140 140 110 70 45 29 17 13 ND 72 250 490 430 370 310 350 190 140 99 75 30 Data from page 56 of 578 and Tables 5 and 7 (p ages 34 and 36) of MRID 45144101; ns no sample;Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 39 Table H. Male and Female RBC AChE Activi ty and Blood TCP Level (0.5 mg/kg) Subject # 3 5 9 12 15 18 MALES AChE (U/L) -10 0 2 4 8 12 24 36 48 72 96 120 144 168 8393 8613 8668 8514 8228 8118 8393 7997 7244 8426 8558 8679 8283 8107 7865 7942 8547 8481 8217 8030 8074 7810 7128 8074 7282 7920 8712 7931 8294 8602 8437 8646 8844 8723 8580 8261 8107 8260 6985 ( ↓ 19) 7535 ( ↓ 12) 7376 ( ↓ 14) 7700 ( ↓ 11) 8877 9471 9218 9031 9482 9229 9394 8910 9053 9504 8096 8921 9537 8547 9713 9889 10021 9944 9845 9471 9680 9670 9119 9889 8525 9207 9548 9295 9405 9471 9977 9658 10516 9515 10153 9746 8822 9702 8767 9163 9130 9581 MALES TCP concentrations (ng/g) in blood samples 0 2 4 8 12 24 36 48 72 96 120 144 168 ND 23 95 97 96 130 140 140 87 58 38 22 14 ND 49 53 51 130 98 100 100 59 24 8 ND ND ND 24 140 130 240 130 130 120 70 41 25 14 10 ND 29 83 96 97 100 110 110 96 67 38 19+ ND ND 160 250 240 210 190 190 190 130 88 56 33 23 ND 51 100 130 130 120 110 110 73 48 29 15 9 Subject # 19 22 26 28 31 36 FEMALES AChE (U/L) -10 0 2 4 8 12 24 36 48 72 96 120 144 168 9724 7282 7986 7810 8041 7843 7832 7535 7623 7953 7997 7931 7689 7744 9086 9218 8932 9141 9097 8349 8866 8987 8921 9394 8646 8437 8195 8657 8063 8602 8448 8239 8305 8437 8041 7810 8129 8701 7689 7975 7744 7733 10010 9900 10252 10593 9966 9779 9746 9834 10109 10516 10153 9581 9218 9130 8800 9515 9526 8239 8866 8602 8756 8228 8855 9482 7920 8811 8734 9086 7139 7156 6853 6501 7007 6996 7365 7068 7117 7579 6474 7073 6589 6837 FEMALES TCP concentrations (ng/g) in blood samples 0 2 4 8 12 24 36 48 72 ND 110 190 210 ND 189 179 180 110 ND 190 380 350 310 220 150 140 59 ND 12 89 110 110 130 190 180 160 ND 61 91 140 130 140 110 91 46 ND 77 120 220 230 210 200 190 130 ND 62 220 260 230 220 230 230 150Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 40 96 120 144 168 88 58 35 23 31 17 ND ND 140 120 107 88 25 14 ND ND 64 41 22 14 83 49 27 19 Data from Tables 5 and 7 (pages 34 and 36) of MRID 45144101Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 41 Table I. Male and Female RBC ACh E Activity (Phase 1 control) Subject # 2 6 8 10 13 17 MALES AChE (U/L) -10 0 2 4 8 12 24 36 48 72 96 120 144 168 8294 9196 8910 8382 8239 8360 8734 8448 7711 8569 8151 8404 7810 8206 7810 8921 8558 8580 8701 8635 8723 7700 7964 8921 7536 7799 7733 8778 6562 6809 6782 6622 6886 6886 6655 6864 6083 6672 6336 6457 6281 6677 8327 7821 8019 8118 7986 7876 8426 8052 7678 7920 6771 7321 7134 7623 6985 8833 8448 8481 8481 8789 8173 7689 8536 8195 8206 8041 7799 8019 7139 7277 7420 7502 7755 7711 7502 7288 7057 7244 7524 7194 7139 7315 Subject # 20 23 27 29 32 34 FEMALES AChE (U/L) -10 0 2 4 8 12 24 36 48 72 96 120 144 168 7178 8239 7568 7953 8239 7898 7645 7249 7931 7843 7415 7513 7722 7689 8481 8723 9053 9504 9174 8657 8844 8712 8800 8789 8272 8360 7975 8437 9724 10208 10010 10076 10373 9713 10098 9284 9603 9416 8800 9053 9570 9317 8382 7865 8382 8426 8701 8118 8195 7843 8184 8437 7073 8283 8206 7722 8294 8723 8932 8855 8569 8085 8481 8261 8008 8822 8305

-

-

- 8866 7953 7722 7755 7843 7953 7755 7183 7568 7997 7002 7249 7249 7013 Data from Table 5.1.1 (pages 57) of MRID 44811002Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 42 Table J. Male and Female RBC ACh E Activity (Phase 2 control) Subject # 37 39 41 44 45 46 MALES AChE (U/L) -10 0 2 4 8 12 24 36 48 72 96 120 144 168 9878 9361 9394 9757 10318 9999 9680 9669 9713 9482 9306 9427 9416 9823 8910 8569 8723 8470 8382 8723 8547 8294 8481 8657 8778 8976 8811 8437 9240 9592 10197 9240 8998 8998 8789 8910 9119 9394 9460 9504 9174 9548 10769 10835 10681 10703 10494 10164 10197 10318 10208 10923 10329 10406 9691 10802 7387 7486 7898 7590 7645 7613 7810 7453 7645 7975 7810 8096 8184 8041 9570 9185 8800 9108 9295 9790 9284 9350 9086 10120 9570 9614 10538 9174 Subject # 50 52 53 54 57 60 FEMALES AChE (U/L) -10 0 2 4 8 12 24 36 48 72 96 120 144 168 8107 8492 8327 8239 8415 8404 8415 8063 8184 9108 8426 8965 7337 8382 7975 7744 7623 7645 7865 7854 7293 7810 7854 8096 7623 7810 7854 7634 8712 8261 8547 8349 9031 8723 8756 8470 8844 9273 8811 8569 9339 8591 8470 8602 8294 8558 8558 8327 8437 8228 8327 9108 9108 8646 8415 8382 8734 9086 9020 8866 9218 8987 9174 8668 8954 9229 8899 9229 8778 9086 8910 9273 8855 8624 9207 9240 8987 9152 9108 8833 8855 9053 8844 9218 Data from Table 9.1.1 (pages 77) of MRID 44811002Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 43 Table K1. Male and Female Urine TCP Level (0.5 mg/kg) Subject # 3 (QR) 5 (QQ) 9 (QQ) 12 (QQ) 15 (QR) 18 (QR) Time interval (hr) MALES TCP con centrations (ng/mL) in urine samples -12-0 0-6 6-12 12-24 24-36 36-48 48-60 60-72 72-84 84-96 96-108 108-120 120-132 132-144 144-156 156-168 BLOQ 98 593 964 636 981 1103 636 496 278 178 120 148 161 98 70 3.4 520 724 907 1440 739 298 453 360 70 140 63 44 9 9.3 5.8 4.4 1396 1217 940 1512 1472 1108 94.5 600 316 146 223 96 56 11.4 11 BLOQ 152 427 678 712 1239 1398 959 680 422 345 464 211 115 122 110 3.4 417 1256 1256 687

ns

ns 1389 465

ns 112 315

ns 190

ns 91 7.1 200 482 1388 836 1688 1605 690 500 366 298 184 196 136 137 78 Subject # 19 22 26 28 31 36 FEMALES TCP concentrations (ng/mL) in urine samples -12-0 0-6 6-12 12-24 24-36 36-48 48-60 60-72 72-84 84-96 96-108 108-120 120-132 132-144 144-156 156-168 19 618 1292 4292 2065 974 1972 2973

ns 919 714 688

ns 711

ns 132 BLOQ 1369 719 1578 490 755 673 597 359 159 96 112 38 12 84 24 5.2 284 344 2057 716 805 2012 653 691 1530 1090 1107 356 1754 1502 504 4.5 500 238 509 360 366 162 200 66 115 50 75 41 29 22 46 BLOQ 347 393 730 365 590 169 384 230 234 57 100 42 62 26 42 2.4 622 468 608 671 726 232 362 514 246 554 276 130 158 161 98 Data from Appendix Table 3 (pages 68 -70) of MRID 45144101; ns no sample;Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 44 Table K2. Male and Female Urine TCP Level (1.0 mg/kg) Subject # 1 (QQ) 4 (RR) 7 (QR) 11 (QQ) 14 (QQ) 16 (QR) Time interval (hr) MALES TCP con centrations (ng/mL) in urine samples -12-0 0-6 6-12 12-24 24-36 36-48 48-60 60-72 72-84 84-96 96-108 108-120 120-132 132-144 144-156 156-168 3.4 496 1373 3217 2224 2896 928 1414 889 816 321 142 220 268 134 74 5 212 1779 1636 2034 1334 2520 974 502 1169 690 807 308 462 362 70 3.2 1286 2499 2941 3706 1126 845 306 107 142 51 44 9 20 8 8 5.3 2128 2764 4758 1967 3109

ns 1790

ns 390

ns 174

ns 98

ns

ns 8.8 4496 7952 3602 3382 4526 2900 3202 2976 2455

ns 808 1254 1216 1137 568 3.4 1614 658 716 3666 2370 2486 759 1579 1301 1418 590 1304 299 360 231 Subject # 21 (QQ) 24 (QQ) 25 (QQ) 30 (QR) 33 (QR) 35 (QR) Time interval (hr) FEMALES TCP concentrations (ng/mL) in urine samples -12-0 0-6 6-12 12-24 24-36 36-48 48-60 60-72 72-84 84-96 96-108 108-120 120-132 132-144 144-156 156-168 6.4 517 2859 2402 1240 2593 3114 716 1351 1885 402 550 280 264 52 184 2.8 1126 1784 1302 1744 2054 1533 1193 1626 1308 466 1027 455 300 136 220 2.8 808 1422 1472 2341 740 1118 792 706 426 218 192 140 76 56 48 7.2 722 3332 1914 2515 2642 2228 1562 1848 1148 1091 1131 894 766 592 556 12.8 169 737 1278 852 1289

ns 752 574 598 402 352

ns 336 168 204 BLOQ 390 466 935 451 806 324 424 404 191 216 142 161 110 98 49 Data from Appendix Table 4 (pages 71 -73) of MRID 45144101; ns no sample;Chlorpyrifos/P. C. Code 059101 DRAFT 5/27/09 Special RBC AChE Inhibition Study (1999 ) Humans (non-guideline)



### 45 Table K3. Male and Female Urine TCP Level (2.0 mg/kg) Subject # 38 (QR) 40 (QQ) 42 (QR) 43 (QR) 47 (QQ) 48 (QR) Time interval (hr) MALES TCP con centrations (ng/mL) in urine samples -12-0 0-6 6-12 12-24 24-36 36-48 48-60 60-72 72-84 84-96 96-108 108-120 120-132 132-144 144-156 156-168 4.8 1308 2030 2794 3263 2822 2674 2216 1318 1656 900 542 501 464 507 414 BLOQ 189 578 2224 1196 1931 1218 730 560 371 572 454 184 185 170 264 BLOQ 878 3282 6164 4532 2818 3458 1213

ns 1556

ns 2398 1507 622 1707 994 8.4 850 1314 2672 5188 5725 1688 2344 1126 1618 886 870 747 794 659 402 7 1506 4704 15323 5549 8610 8865 8129 5416 3905 2444 2342 1298 1512 1482

- 3.0 949 784 3360 3262 2662 853 1848 752 659 427 722 428 642 452

- Subject # 49 (QQ) 51 (QR) 55 (RR) 56 (QQ) 58 (QQ) 59 (QQ) Time interval (hr) FEMALES TCP concentrations (ng/mL) in urine samples -12-0 0-6 6-12 12-24 24-36 36-48 48-60 60-72 72-84 84-96 96-108 108-120 120-132 132-144 144-156 156-168 4.4 882 2183 3310 1453 1897 958 1130 645 570 218 286 226 288 150 133 10.9 1413 3688 6064 1786 3736 2114 1443 1286 2526 1078 1014 918 474 696 616 5.1 676 1850 5275 1658 4537 1662 2548 533 354 332 448 206 329 212 98 10.9 1246 7966 8148 6270 7068

-

-

-

-

-

-

-

-

-

- 4.5 1690 994 1868 2304 2458 1538 1469 1496 1530 604 631 84 85 182 147 4.2 1881 4682 5036 6622 3822 2902 2370 1855 1198 842 1113 805 636 228 156 Data from Appendix Table 5 (pages 74 -76) of MRID 45144101; ns no sample;