Chlorpyrifos (PC 059101) Air Photolysis (2012)/Page 1 of 26

MRID 48789701 OPPTS 835.2370

DATA EVALUATION RECORD



### Test Material: Chlorpyrifos

MRID 48789701

Title: Munoz, A. 2012. Gas-phase photol ysis and photo-oxidation of chlorpyrifos and chlorpyrifos-oxon

EPA PC Code: 059101

OCSPP Guideline: 835.2370

For Cambridge Environmental

Primary Reviewer: Lynne Binari Signature:

Date: 9/11/12

Secondary Reviewer: Kathleen Ferguson Signature:

Date: 9/11/12

QC/QA Manager: Joan Gaidos Signature:

Date: 9/11/12Chlorpyrifos (PC 059101) MRID 48789701

Page 3 of 26 

### Table 1. Results Synopsis: Phototransformation in Air

Compound

Name Observed

DT 50 (hours) Observed

DT 90 (hours) Calculated

Half-life (hours) A Model Parameters and

Statistics Adjusted

Half-life (days) B Phototransformation Products

Common Name (maximum approximate ppb observed, associated interval) C

Photolysis

Chlorpyrifos
[300 ± 5oK (22-32oC)] ca. 5 >5.5 4.3 J(CHL) = <4.5 x 10 -5 s -1

R 2 = 0.947 -- Chlorpyrifos-oxon (50 ppb, ca

. 5.5 hours) Formaldehyde (30 ppb, ca . 1 hour)

SO 2 (10 ppb, ca . 5.5 hours) Acetaldehyde (5 ppb, ca . 1-5 hours)

Chlorpyrifosoxon [307 ± 5oK (29-39oC)] ca . 4 >4 4.4 J(CHLO) = <4.4 x 10 -5 s -1

R 2 = 0.785 -- Formaldehyde (10 ppb, ca . 4.4 hours) HCl (10 ppb, ca . 4.4 hours)

Photo-oxidation (HONO)

Chlorpyrifos
[303 ± 5oK (25-35oC)] ca. 0.5 >2 1.3 k OH (CHL) = (9.1 ± 1.8) x

10 -11 cm 3 molecule -1 s -1 -- Chlorpyrifos-oxon (40 ppb, ca

. 2 hours) Ozone (30 ppb, ca . 1 hour) Formic acid (5 ppb, ca . 1.5 hours) Formaldehyde (20 ppb, ca . 1.5-2 hours)

SO 2 (20 ppb, ca . 1.5-2 hours) Pyridinol (5 ppb, ca. 0.5-2 hours) PAN (1 ppb, ca . 1 hour)

Chlorpyrifosoxon [303 ± 5oK (25-35oC)] ca . 3.5 >3.5 7.8 k OH (CHLO) = (1.6 ± 0.8)

x 10 -11 cm 3 molecule -1 s -1 -- Ozone (40 ppb, ca . 3.5 hours) Formic acid (25 ppb, ca . 3 hours) Formaldehyde (20 ppb, ca . 2 hours)

SO 2 (15 ppb, ca . 1.5 hours) HCl (10 ppb, ca . 3.5 hours) Methylglyoxal (10 ppb, ca . 3.5 hours) Pyridinol (5 ppb, ca . 1.5 hours)

A Model parameters and statistics and half-lives calculated by the study author. Observed DT 50 and DT 90 values were

estimated by the reviewer. Calculated half-lives were not determined by the reviewer because only graphical representations of test compound concentrations were provided.

B Dark control-adjusted and adjusted to a 12-hour/day photoperiod at 40°N latitude.

C Concentrations (ppb) estimated by reviewer. -- = Not reported.Chlorpyrifos (PC 059101) MRID 48789701

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### I. Materials And Methods

A. Materials:

1. Test materials Chlorpyrifos (CHL, p. 9) Specific activity: Not applicable. Radiochemical purity: Not applicable.
Chemical purity: Not reported.
Batch No. Not reported.

Chlorpyrifos-oxon (CHLO, p. 10) Specific activity: Not applicable. Radiochemical purity: Not applicable. Chemical purity: Not reported.

Batch No. Not reported.

Solubility in water: Chlo rpyrifos: 1.05 mg/L (p. 9) UV absorption: Not reported.

2. Reference Compounds: The following compounds were used in the analysis.

Table 2. Reference Compounds

Applicant’s Code Name Chemi cal Name Purity (%) Lot No.

Chlorpyrifos (CHL) O,O-Diethyl-O-(3,5,6-trichloro-2-pyridyl) phosphorothioate -- --

Chlorpyrifos-oxon (CHLO) Phosphoric acid, diethyl 3,5,6-trichloro-2-pyridyl ester -- --

Pyridinol 3,5,6-Trichloro-2-pyridinol -- --

CYCL Cyclohexane 99.7 --

SF 6 Sulphur hexafluoride 99.9 --

TMB 1,3,5-Trimethylbenzene (mesytilene) 99 --
Data obtained from pp. 9-13 of the study report. -- = Not reported.Chlorpyrifos (PC 059101) MRID 48789701

Page 5 of 26 

### B. Study Design

1. Experimental Conditions

Table 3. Experimental Design

Parameter Description

Nature of light source Natural sunlight conditions at outdoor European Photoreactor (EUPHORE) in Valencia, Spain: longitude = -0.5o, latitude = 39.5oN. Experiments conducted between September 6-19, 2011.
Emission wavelength spectrum Not applicable.

Nominal light intensity Not reported. Graphical represen tations of the radiation (JNO 2 ) time profiles during the experiments are presented in Figure 5B, p. 27; Figures 14A-B, p. 39; Figure 19B, p. 44; Figure 27B, p. 58; Figure 35A-B, p. 68; and Figure 41B, p. 73.
Filters used Fluorine-ethene-propene (FEP) foil chambers
Relationship to natural sunlight FEP transmission >80% for 280-640 nm. 1

Method used to determine relations between light source and summer sunlight Inside chamber: Actinic flux measured using a calibrated filter radiometer specific to the photolysis frequency of NO 2 , and light intensity measured using a calibrated spectroradiometer (Bentham DM300, Gigahertz Optik Gmbh).

Outside chamber : Pyranometer (CM3, Kipp & Zonen) measured global solar radiation (W/m 2 ) at 300 to 3,000 nm and photolysis frequency of NO 2 → NO + O( 3 P) reaction. In addition, the Tropos pheric Ultraviolet and Visible (TUV) Radiation Model (UCAR/NCAR/ACD) 2 used to calculate global radiation (RAD, W/m 2 ) and photolysis frequency (J, s -1 ) of some species for clear sky

conditions. Pyranometer radiation and TUV model data were compared to obtain a factor of the real atmospheric conditions during the experiments using the schematic presented in Figure 4, p. 20. Comparative photolysis frequency time profiles are presented in Figure 7, p. 28 and Figure 29, p. 59.
Duration of the tests (includes darkness intervals prior to sunlight exposure and at end of test after chamber closure) 8 hours 49 minutes to 10 hours 29 minutes.

Solution volume Not applicable. Test materials introduced into chamber in gas phase.

Test

concentration Nominal Not reported.
Measured (initial mixing ratio) Experiments 1-4 using chlorpyrifos: 80-140 ppbv. Experiments 5-8 using chlorpyrifos-oxon: 150-300 ppbv.

Control conditions Conventional control (dark) samples were not used. Treated air samples were removed during darkness interval ( ca . 1.5-2.5 hours) prior to sunlight

exposure.

Number of replicates Irradiated Three types of experiments were conducted with each test material: 1) Photolysis kinetics and products (Experiments 1 and 5; test material,

SF 6 , CYCL), 2) Photo-oxidation kinetics (Experiments 2-3 and 6-7; test material,

SF 6 , TMB, CYCL, HONO), and 3) Photo-oxidation products (Experiments 4 and 8; test material, SF 6 , HONO). Darkness

Test apparatus Irradiated Outdoor European Photoreactor (EUP HORE) consisting of two identical half-sphere FEP foil chambers with volumes of ca . 200 m 3 (Figure 1, p. 14).

The surface:volume ratio is close to one to minimize losses by adsorption onto the chamber walls. Retractable half-sphere protective housings areChlorpyrifos (PC 059101) MRID 48789701

Page 6 of 26 Parameter Description

Darkness closed to exclude light. Two mixing fans within each chamber are used to achieve homogenous concentration. The floor is water-cooled. An air purification/drying system cleans and dries incoming air. Temperature and humidity within the chamber are continuously monitored using PT-100 thermocouples and a dew-point mirror sy stem (Walz TS-2), respectively. The chamber is equipped with various analytical instruments for in situ analysis and/or sampling as described below in section 2. Description of Analytical

Procedures

.

Traps Organics The following were utilized and are described below in section 2. Description of Analytical Procedures.

FTIR. Ozone, NOx and SO 2 monitors.

TEOM and SMPS aerosol mass concentration monitors.

SPME. C-18 solid-phase cartridges and glass fibe r filters (0.45-μm, internal porous). CO 2

Test material application Solvent Not applicable.

Test solution volume

used/treatment Not applicable.

Application method Chlorpyrifos and chlorp yrifos-oxon were "gently heated" to accelerate

introduction into the chamber.
Evaporation of application solvent Not applicable.

Indication of test material adsorbing to walls of test apparatus? Yes. In the photolysis experiments (Experiments 1 and 5), concentrations of both chlorpyrifos and chlorpyrifos-oxon "increased slightly" during the initial 30 minutes of exposure, then decreased.
Correction of adsorption? Yes

Correction for leak rate? Yes; k dil based on loss of SF 6 Correction for dilution from sampling?

Experimental

conditions Temperature (°C) Experiment 1: 300 ± 5oK (22-32oC). Experiment 5: 307 ± 5oK (29-39oC). Experiments 2-4 and 6-8: 303 ± 5oK (25-35oC).
Continuous irradiation Test materials and reference compounds introduced into dark chamber, allowed to equilibrate, then sunlight exposure was initiated. Irradiation was conducted continuously for ca . 3.5-6 hours. Continuous darkness:

Sample storage before analysis None reported. Data obtained from pp. 4, 8, 14-16, 19-23, 26, 29, 31, 38, 44, 57, 60-62, 66-68, 72; Figures 5A-B, p. 27; Figure 7, p. 28; Figure 10, p. 33; Figures 13A-B, p. 39; Figures 14A-B, p. 39; Figures 19A-B, p. 44; Figures 27A-B, p. 58; Figure 29, p. 59; Figure 32, p. 63; Figures 34A-B, p. 68; Figures 35A-B, p. 68; Figures 41A-B, p. 73; Annex 8.3, pp. 119-122 of the study report.1 Bohaty, R.F.H. August 4, 2011. Environmental Fate Technical Team. Study Review: gas-phase photolysis and photooxidation of chlorpyrifos and chlorpyrifos-oxon. 2 University Corporation for Atmosphe ric Research/National Center for Atmo spheric Research/Atmospheric Chemistry

Division.Chlorpyrifos (PC 059101) MRID 48789701

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### 2. Description of Analytical Procedures

In situ and On-line Analyses:

FTIR spectrometer (NICOLET 6700), fitted with a MC T-detector and combined with a long-pass absorption system (total optical length 554 m), was used for measurement of compounds in the spectral range between 650-4,000 cm -1 

### (pp. 15-16). Spectra were take n at a resolution of 1 cm -1 

### and sampling time of 5 minutes/spect rum. Compound groups detected by FT IR are listed in Table 2 (p. 17). Spectra are presented in Annex 8.1, pp. 87-96. SF 6 

### was measured to quantify gas dilution.

Ozone (Monitor Labs 9810), NOx (Dasibi, ML9841A with TiO 2 

### catalytic converter) and SO 2 

### (Thermo Scientific 43i) concentrations were measured with the specified analyzers (p. 19).

Aerosol mass concentrations were measured with tw o instruments (pp. 21-22). Real-time aerosol mass concentrations were measured with a tape red element oscillating monitor (TEOM, model 1400a, Ruppercht and Patashnick Co. Inc.) at a 1-mi nute scan rate and sampling flow of 3 L/minute.

Particle size distribution and aerosol mass concentr ations were measured with a scanning mobility particle sizer (SMPS, model 3080, TSI Inc.) equippe d with a differential m obility analyzer (DMA, model 3081) and condensation particle counter (CPC, model 3775). The SMPS measured size

distributions in the 11-982 nm diam eter range in real time with a 5- minute scan rate at 27oC; sheath and aerosol sampling flows were 4 L/minute and 0.30 L/minute, respectively. Aerosol volume

concentrations from the SMPS were converted to aerosol mass concentrations by assuming a density of 1 g/cm 3



### .

Off-line Analyses :

Solid-Phase Microextraction (SPME). Pre-conditioned fibers (65-μm) coated with polydimethylsiloxane/divinylbenzen e (PDMS/DVB, Supelco) were expos ed to the air at floor level in the chamber for 10 minutes, then analyzed dir ectly by GC-FID with an HP-5MS column (0.25 mm x 30 m, 0.25 mm film thic kness, crosslinked 5% Ph Me Siloxane; pp. 22-23).

C-18 and filter samples (for products determination experi ments, pp. 23-24). Blank control and treated air samples were collect ed using C-18 solid-phase cartri dges (type not specified) at a sampling flow rate of 1 L/minute. Aerosol sa mples were collected us ing pre-heated 47-mm diameter glass fiber filters (0.45- μm, internal porous) and a samp ling flow rate of 23 L/minute.

Particle mass determinations were made us ing a microbalance (model MC21S, Sartorius). Cartridges and filters were extracted with methylen e chloride:acetonitrile (1:1, v:v) and sonication. The extract was centrifuged, taken to dryness un der nitrogen, reconst ituted in methylene chloride:acetonitrile and again ta ken to dryness. The sample was derivatized for 24 hours at room temperature with O-(2,3,4,5,6-pentafl uorobenzyl)hydroxylamine (PFBHA) and 4- fluorobenzaldehyde as an internal standard of carbonyl derivatization. The sample was then derivatized for 1 hour at 90oC with N-methyl-N -trimethyl-silyltrifluoroacetamide (MSTFA) and

chlorosuccinic acid as an in ternal standard of hydroxyl deri vatization. The double derivatized sample was then analyzed by GC/MS with the same column as used for SPME.

Detection Limits (LOD, LOQ) for the Paren t Compound and Transformation Products: Limits of detection for FTIR analyses are presented in Table 4 . Limits of detection and quantification for all other me thodologies were not reported.Chlorpyrifos (PC 059101) MRID 48789701

Page 8 of 26 

### Table 4. Compounds Detected by FTIR During the Experiments

Compound Formula Detection Limit (ppb) Accuracy (%) Analysis Region (cm -1 )

Chlorpyrifos C 9 H 11 Cl 3 NO 3 PS 1.7 30.0 760-1225

Chlorpyrifos-oxon C 9 H 11 Cl 3 NO 4 P 3.0 30.0 760-1225

3,5,6-Trichloro-2-pyridinol C 5 H 2 Cl 3 NO 4.0 30.0 760-1225

1,3,5-Trimethylbenzene C 9 H 12 1.3 2.0 800-860

Cyclohexane C 6 H 12 15.3 9.0 800-1100

0.7 7.0 2800-2900

Formaldehyde HCHO 3.0 3.3 2700-2900

Formic acid HCOOH 0.7 4.5 1050-1150

Glyoxal C 2 H 2 O 2 2.5 8.0 2750-2900

Hydrochloric acid HCl 2.7 30.0 2700-2900

Nitric acid HNO 3 3.4 4.5 825-950

Nitrous acid HONO 2.5 7.0 760-900

Methylglyoxal C 3 H 4 O 2 2.7 15.0 2750-2900

Ozone O 3 3.0 10.0 950-1100

Peroxyacetyl nitrate C 2 H 3 NO 5 0.7 3.0 760-1225

Sulphur hexafluoride SF 6 0.1 10.0 920-955
Data obtained from Table 3, p. 18 of the study report.Chlorpyrifos (PC 059101) MRID 48789701

Page 9 of 26 

### II. Results and Discussion

A. Data

Study results including di stribution of radioactivity are presented in Tables 5a-5b.

Table 5a. Photodegradation of Chlorpyrifos , Expressed as Approximate ppb, in Air

Sampling Interval (hours) Prior to irradiation ( ca . 1.5 hours) Chamber opened to sunlight (initial 30 minutes) Chamber closed (5 hours 21 minutes irradiation) End of test ( ca . 1 hour)

Replicate 1 1 1 1

Component Irradiated [300 ± 5°K (22-32oC)]

Chlorpyrifos (CHL) 1 85 90 40 35

Chlorpyrifos-oxon (CHLO) 1 20-25 25 50 50

SO 2 2 <5 <5 10 10

Ozone 1, 3 5 5 115 110

Formic acid (HCOOH) 1, 3 <5 <5 20 20

Formaldehyde (HCHO) 4 -- 30 10 --

Acetaldehyde (CH 3 CHO) 4 -- 5 5 --

Glyoxal (C 2 H 2 O 2 ) 5 Possible compound, not quantified.

Methylglyoxal (C 3 H 4 O 2 ) 5 Possible compound, not quantified.

Others 5, 6 Not quantified.

Total Recovery Mass balances were not determined.

Component Control (Dark)

Dark control samples only taken during 1.5-hour equilibration interval prior to sunlight exposure.

Results estimated by the reviewer from Figure 10, p. 33 of the study report. Irradiation interval from Annex 8.3, Table 16, p. 119. Experiment temperature obtained from p. 31 of the study report. -- = Not reported.

1 FTIR.

2 Monitor, corrected for losses.

3 May have originated from cyclohexane used to scavenge OH and Cl radicals (p. 34).

4 LC/MS (not described in analytical methods); sampled at two intervals, after ca . 1 hour and 5 hours of irradiation.

5 C-18 solid-phase cartridge and GC/MS (Table 7, p. 36).

6 Numerous unknowns (Tables 5-7, pp. 35-36). Analysis of C-18 cartridges with and without derivatization did not

provide additional information for identifications, ex cept that pyridinol was not detected (p. 34).Chlorpyrifos (PC 059101) MRID 48789701

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### Table 5b. Photodegradation of Chlorpyrifos-o xon, Expressed as Approximate ppb, in Air

Sampling Interval (hours) Prior to irradiation ( ca . 2.5 hours) Chamber opened to sunlight (initial 30 minutes) Chamber closed (4 hours 23 minutes irradiation) End of test ( ca . 15 min)

Replicate 1 1 1 1

Component Irradiated [307 ± 5°K (29-39oC)]

Chlorpyrifos-oxon (CHLO) 1 125 150 90 75

Ozone 1, 2 <5 <5 75 75

Formic acid (HCOOH) 1, 2 <5 <5 20 20

Formaldehyde (HCHO) 3 <5 <5 10 <5

HCl 3 <5 <5 10 <5

Pyridinol 4 Possible compound, not quantified.

Glyoxal (C 2 H 2 O 2 ) 4 Possible compound, not quantified.

Methylglyoxal (C 3 H 4 O 2 ) 4 Possible compound, not quantified.

Others 4, 5 Not quantified.

Total Recovery Mass balances were not determined.

Component Control (Dark)

Dark control samples only taken during 2.5-hour equilibration interval prior to sunlight exposure.

Results estimated by the reviewer from Figure 32, p. 63 of the study report. Irradiation interval from Annex 8.3, Table 20, p. 121. Experiment temperature obtained from p. 62 of the study report. -- = Not reported.

1 FTIR.

2 May have originated from cyclohexane used to scavenge OH and Cl radicals (p. 34).

3 Method not reported.

4 C-18 solid-phase cartridge and GC/MS (Tables 13-14, pp. 64-65).

5 Numerous unknowns (Tables 12-14, pp. 64-65). Analysis of C-18 cartridges with and without derivatization did not

provide additional information for identifications (p. 63).Chlorpyrifos (PC 059101) MRID 48789701

Page 11 of 26 

### B. Mass Balance

Mass balances were not determined.

C. Volatilization

Experiments conducted in gas-phase.

D. Transformation of Chlorp yrifos and Chlorpyrifos-oxon

Transformation kinetics of th e chlorpyrifos and chlorpyr ifos-oxon are summarized in Table 6 , with transformation product info rmation summarized in Tables 7a-7b . Degradation rate s were quantified taking into account losses from the test chamber due to leak age, dilution from sampling and adsorption/desorption on the chamber walls (p. 8).

Chlorpyrifos - Photolysis . Degradation of chlorpyrifos in an irradiated gas-phase was rapid. The study author calculated a lifetime of 6.2 hours (JNO 2 

### = 9.5 ± 1.7 x 10 -3 

### ) and a half-life of 4.3 hours (p. 31). Chlorpyrifos slig htly decreased during the ca . 1.5-hour darkness interval prior to irradiation (Figure 10, p. 33).

Despite interferences, particle formation during irradiation was detected with both the SMPS and TEOM systems, with secondary organic aerosol (SOA) yields from chlorpyrifos photolysis,

calculated from aerosol mass formed and corrected fo r wall losses, of 1.6% for both systems (p. 37).

Chlorpyrifos - Photo-oxidation (HONO) . The study author calculated a lifetime of 1.95 hours and a half-life of 1.3 hours for an average 12-hour day time concentration of OH radicals of 1.56 x 10 6



### radical/cm 3 

### (p. 43). Dark control samples were not taken in the pr esence of HONO.

The cyclohexane rate loss in relation to that of TMB of [k OH 

### (CYCL)/k OH 

### (TMB] = 0.13, compared

to the calculated value of 0.14 based on their rate constants for reaction with OH, indicated that Cl production in the reaction of chlorpyrifos with OH radicals did not signifi cantly affect the rate constant [k OH 

### (CHL)] determined for the reaction of OH with chlorpyrifos (p. 41).

Concentrations measured by FTIR and SPME-GC/FID were similar with no irradiation (start and end of test), but differed under sunlight exposure, indicating an intermediate other than chlorpyrifos-oxon and pyridinol was formed, but with similar structural features as those compounds (pp. 41, 44).

An absence of HCl in the products formed indicated that degradation of th e aromatic ring did not occur in the initial stag es of oxidation (p. 48).

Despite interferences, SOA yields from chlorpyrif os photo-oxidation, calculated from the ratio of aerosol mass formed to amount of chlorpyrifos r eacted at maximum particle concentration, were 26% and 14% for TEOM and SMPS, respectively (p. 57).

Chlorpyrifos-oxon - Photolysis . Degradation of chlorpyrifos-oxon in an irradiated gas-phase was rapid. The study author calculat ed a lifetime of 6.2 hours (JNO 2 

### = 9.5 ± 1.7 x 10 -3 

### ) and a half-life of 4.4 hours (p. 62). Chlorpyrifos-oxon remain ed relatively constant during the ca . 2.5-hour darkness interval prior to irradi ation (Figure 32, p. 63).Chlorpyrifos (PC 059101) MRID 48789701

Page 12 of 26 

### Despite interferences, particle formation during ir radiation, as measured by SMPS, was determined to be "unimportant" (p. 66).

Chlorpyrifos-oxon - Photo-oxidation (HONO) . The study author calculate d a lifetime of 11.2 hours and a half-life of 7.8 hours for an average 12-hou r daytime concentration of OH radicals of 1.56 x

10 6 

### radical/cm 3 

### (p. 72). Dark control samples were not taken in the presence of HONO.

The cyclohexane rate loss in relation to that of TMB of [k OH 

### (CYCL)/k OH 

### (TMB] = 0.14, compared

to the calculated value of 0.14 based on their rate constants for reaction with OH, indicated that Cl production in the reaction of chlor pyrifos-oxon with OH radicals did not significantly affect the rate constant [k OH 

### (CHL)] determined for the reaction of OH with chlorpyrifos-oxon (p. 69).

Concentrations measured by FTIR and SPME-GC/FID were similar with no irradiation (start and end of test), but differed under s unlight exposure, indicating an unidentified intermediate having

similar structural features as ch lorpyrifos-oxon was formed (pp. 70, 73).

An absence of HCl in the products formed indicated that degradation of th e aromatic ring did not occur in the initial stag es of oxidation (p. 76).

Despite interferences, SOA yields from chlo rpyrifos-oxon photo-oxidation, calculated from the

ratio of aerosol mass formed to amount of ch lorpyrifos-oxon reacted at maximum particle concentration, were 35% and 11% for TEOM and SMPS, respectively (p. 79).Chlorpyrifos (PC 059101) MRID 48789701

Page 13 of 26 

### Table 6. Phototransformation in Air

Compound

Name Observed

DT 50 (hours) Observed

DT 90 (hours) Calculated

Half-life (hours) A Model Parameters Model

Statistics Dark Control Adjusted

Half-life (hours) Environmental

Half-life

(days)

Photolysis

Chlorpyrifos
[300 ± 5oK] ca. 5 >5.5 4.3 k dil = 1.2 x 10 -5 s -1

k dil + k wall (T) + k des (T) =

-7 x 10 -6
J(CHL) = <4.5 x 10 -5 s -1 R 2 = 0.947

-- --

Control: Chlorpyrifos Dark control samples were not

used. -- --

Chlorpyrifosoxon [307 ± 5oK] ca . 4 >4 4.4 k dil = 1.04 x 10 -5 s -1

k dil + k wall (T) + k des (T) =

-4 x 10 -5
J(CHLO) = <4.4 x 10 -5 s -1 R 2 = 0.785 -- --

Control:Chlorpyrifosoxon Dark control samples were not

used. -- --

Photo-oxidation (HONO)

Chlorpyrifos
[303 ± 5oK] ca. 0.5 >2 1.3 k OH (CHL) = (9.1 ± 1.8) x

10 -11 cm 3 molecule -1 s -1 -- -- --

Control: Chlorpyrifos Dark control samples were not

used. -- --

Chlorpyrifosoxon [303 ± 5oK] ca . 3.5 >3.5 7.8 k OH (CHLO) = (1.6 ± 0.8) x

10 -11 cm 3 molecule -1 s -1 -- -- --

Control:Chlorpyrifosoxon Dark control samples were not

used. -- --

A Results obtained from pp. 30-31; Figure 9, p. 31; pp. 42-43, 61-62; Figure 31, p. 62; pp. 71-72 of the study report. Halflives were calculated by the study author. Photolysis rate s take into account losses from the chamber through leakage, dilution from sampling and adsorption/desorption on the chamber walls (pp. 8, 30-31, 60-62). Photo-oxidation rates take into account losses from the chamber through leakage, dilution from sampling, adsorption/desorption on the chamber walls and photolysis of the test compound prior to addition of HONO (pp. 38-39, 66-67). Observed DT 50 and DT 90 values were estimated by the reviewer (Figure 10, p. 33; Figure 24, p. 47; Figure 32, p. 63; Figure 46, p. 76; DER Attachment 2). Calculated half-lives were not determined by the reviewer because only graphical representations of test compound concentrations were provided. -- = Not reported.Chlorpyrifos (PC 059101) MRID 48789701

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### Table 7a. Transformation Products of Chlorpyrifos

Transformation Products Maximum ppb

Observed Associated

Interval Final ppb

Observed Final

Interval 1 Calculated

Molar Yield (%)

Photolysis

Irradiated Samples Chlorpyrifos-oxon (CHLO) 50 ca . 5.5 hours 50 ca . 5.5 hours 11

SO 2 10 ca . 5.5 hours 10 ca . 5.5 hours 82

Ozone (FTIR) 2 115 ca . 5.5 hours 115 ca . 5.5 hours --
Formic acid (HCOOH) 2 20 ca . 5.5 hours 20 ca . 5.5 hours --
Formaldehyde (HCHO) 3 30 ca . 1 hour 10 ca . 5 hours

-- Acetaldehyde (CH3CHO) 3 5 ca . 1 hour 5 ca . 5 hours

-- Glyoxal Possible compound, not quantified (Table 7, p. 36).

Methylglyoxal Possible compound, not quantified (Table 7, p. 36).

Others Numerous unknowns, not quantified (Tables 6-7, pp. 35-36).

Dark

Controls During the dark interval prior to irradiation, chlorpyrifos-oxon were detected at a maximum of ca

. 25 ppb at 1.5 hours just prior to opening the chamber. SO 2 was also reportedly detected, but could not be quantified from the graphic representation (p. 32; Figure 10, p. 33).

Photo-oxidation (HONO)

Irradiated Samples Chlorpyrifos-oxon (CHLO) 40 ca . 2 hours 40 ca . 2 hours 10 and 30 4

SO 2 20 ca . 1.5 hours 20 ca . 2 hours 17 ± 5

Ozone (Monitor) 7 30 ca . 1 hour 10 ca . 2 hours 30 ± 10

Ozone (FTIR) 50 ca . 0.5 hour 25 ca . 2 hours

-- Formic acid (HCOOH) 20 ca . 2 hours 20 ca . 2 hours

-- Formaldehyde (HCHO) 20 ca . 1.5 hours 20 ca . 2 hours <17

Pyridinol 5 ca . 0.5 hour 5 ca . 2 hours 8 ± 4 5

Peroxyacetyl nitrate

(PAN) 6 1 ca . 1 hour <1 ca . 2 hours <10

Aerosols

-- -- -- -- 25 ± 8

Glyoxal Possible compound, not quantified (Table 11, p. 53).

Others Numerous unknowns, not quantified (Tables 9-11, pp. 50-54).

Dark

Controls Dark control samples were not taken in presence of HONO.

Concentrations in terms of ppb estimated by the reviewer from Figure 10, p. 33; Figure 24, p. 47 of the study report. Calculated yields reported by study author (p. 32; Table 8, p. 49).

1 Chamber closed. 2 Yields not calculated because may have originated from cyclohexane used to scavenge OH and Cl radicals (p. 34). 3 From analyses of samples taken after ca . 1 and 5 hours of irradiation.

4 Not corrected and corrected for secondary losses with OH, where k OH (CHLO) = 1.5 x 10 -11 (this study) and

[OH] average = 1.31 x 10 -7 (calculated from losses of CHL based on k OH (CHL) = 9.10 x 10 -11 ; Table 8, p. 49). 5 Corrected for secondary losses with OH, where k OH (PYRDIINOL) = 1.8 X 10 -13 (EPIWEB) and [OH] avearge = 1.31 x

10 -7 (calculated from losses of CHL based on k OH (CHL) = 9.10 x 10 -11 ; Table 8, p. 49). 6 Secondary product. Yield dependent on NO 2 /NO concentration ratio. Corrected by thermal losses of PAN at 303oK k

= 3.3 x 10 -4 s -1 (Table 8, p. 49). 7 Discrepancies between FTIR and Monitor for ozone due to possible positive interferences with FTIR (p. 48). -- = Not reported.Chlorpyrifos (PC 059101) MRID 48789701

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### Table 7b. Transformation Pro ducts of Chlorpyrifos-oxon

Transformation Products Maximum ppb

Observed Associated

Interval Final ppb

Observed Final Interval 1

Photolysis

Irradiated Samples 2 Ozone (FTIR) 3 75 ca . 4.4 hours 75 ca . 4.4 hours

Formic acid (HCOOH) 3 20 ca . 4.4 hours 20 ca . 4.4 hours

Formaldehyde (HCHO) 10 ca . 4.4 hours 10 ca . 4.4 hours

HCl 10 ca . 4.4 hours 10 ca . 4.4 hours

Pyridinol Possible compound, not quantified (Tables 13-14, pp. 64-65)

Glyoxal Possible compound, not quantified (Table 14, p. 65).

Methylglyoxal Possible compound, not quantified (Table 14, p. 65).

Others Numerous unknowns, not quantified (Tables 13-14, pp. 64-65).

Dark

Controls None detected during the ca . 2.5-hour dark interval prior to irradiation.

Photo-oxidation (HONO)

Irradiated Samples Ozone (Monitor) 4 40 ca . 3.5 hours 40 ca . 3.5 hours

Ozone (FTIR) 4 60 ca . 3 hours 40 ca . 3.5 hours

Formic acid (HCOOH) 25 ca . 3.5 hours 25 ca . 3.5 hours

Formaldehyde (HCHO) 20 ca . 2 hours 15 ca . 3.5 hours

SO 2 15 ca . 1.5 hours 10 ca . 3.5 hours

HCl 10 ca . 3.5 hours 10 ca . 3.5 hours

Methyglyoxal (m-Gly) 10 ca . 3.5 hours 10 ca . 3.5 hours

Pyridinol 5 ca . 1.5 hours <5 ca . 3.5 hours

Peroxyacetyl nitrate (PAN) Observed, not quantified (p. 75)

Acetone Possible compound, not quantified (Table 15, p. 77)

Others Numerous unknowns, not quantified (Table 15, pp. 77-78).

Dark

Controls Dark control samples were not taken in presence of HONO.

Concentrations in terms of ppb estimated by the reviewer from Figure 32, p. 63; Figure 46, p. 76 of the study report.

1 Chamber closed. 2 No identifiable products detected with FTIR (p. 62). 3 May have originated from cyclohexane used to scavenge OH and Cl radicals (p. 34). 4 Yield approached 30% (O 3 monitor, p. 76). Discrepancies between FTIR and Monitor for ozone due to possible

positive interferences with FTIR (p. 76).Chlorpyrifos (PC 059101) MRID 48789701

Page 16 of 26 

### A transformation pathway was provided by the study author and is illustrated below (Figure 25, p. 56).

Figure 1. Photo-oxidation (HONO) degrada tion pathway for chlorpyrifos. Pathway A: Addition of

OH to the PS bond. Structures include identified and quantified compounds, plus tentatively identified compounds through de rivatization and GC/MS.Chlorpyrifos (PC 059101) MRID 48789701

Page 17 of 26 

### III. Study Deficiencies and Reviewer’s Comments

1. Dow AgroSciences previously submitted to EFED a study outline for investigation of gas-phase photolysis and photo-oxidation of chlorpyrifos and chlorpyrif os-oxon. The following are the deficiencies (a, b, c, etc.) EFED identified in the study outline and whether or not those

deficiencies were addres sed in the study conduct.

a) The test substances are unlabeled. Radiolabeled test substances are pref erred specifically to monitor mass balances throughout the study and to ensure that all tran sformation products at

≥ 10% of the applied or that are toxicologica lly relevant are identified. Additionally, would potential losses from the system through diluti on or sorption of the test material to the

incubation vessel walls be monitored?

i. The test substances used in this study were unlabeled. Additionally, the test substances were incompletely characterized; purities and lot/batch numbers were not reported.

ii. Material balances were not monitored in th is study. Molar yields were estimated for photolysis and photo-oxidation of chlo rpyrifos (p. 32; Table 8, p. 49).

iii. It could not be determined whether or not any transformation products at ≥ 10% of the applied or that are toxicologi cally relevant were present, but not identified. FTIR and Solid-Phase Microextraction (SPME)/G C-FID were the primary methods for identifications. It was unclear whether the prov ided FTIR spectra were reference spectra or experimental spectra from sample analys es (pp. 18-19; Annex 8.1, pp. 87-96). GC/MS of derivatized samples obtained from C-18 SPE cartridges only partially characterized possible compounds and/or structures.

iv. Losses from the test chamber due to leakage, dilution from sampling and adsorption/desorption on the chamber walls were quantified and ta ken into account for determination of degrada tion rates (pp. 8, 29-30, 60-61).

b) At a minimum, reference standards and analys is methods for chlorpyrifos, chlorpyrifos-oxon and 3,5,6-trichloro-2-pyridinol should be utili zed. Those three refere nces standards were utilized (pp. 9-11). The other reference com pounds, cyclohexane, sul phur hexafluoride and 1,3,5-trimethylbenzene, were included as monitoring controls (pp. 12-13).

c) Temperature maintenance was not specified in the study outline. The incubation temperature should be relatively constant at 30oC. The chamber is equipped with a water-cooled floor, mixing fans and an air purifi cation/drying system (p. 14). Ei ght experiments were conducted at the following temperatures:

Experiment 1 (chlorpyrifos photolys is) at 300 ± 5oK (22-32oC; p. 31), Experiment 5 (chlorpyrifos-oxon photolysis) at 307 ± 5oK (29-39oC; p. 62), and Experiments 2-4 (chlorpyrifos photo-oxida tion) and 6-8 (chlorpyrifos-oxon photooxidation) at 303 ± 5o K (25-35oC; p. 38).Chlorpyrifos (PC 059101) MRID 48789701

Page 18 of 26 

### d) The ability of the SPME to accurately quan tify chlorpyrifos, chlorpyrifos-oxon and 3,5,6- trichloro-2-pyridinol in the chamber should be shown. FTIR was used as the primary analytical method. No method validations we re included as part of the submission.

e) Experiments should be conducted in repli cate. Only the photo-oxidation kinetics experiments (Experiments 2-3 for chlorpyrif os, and 6-7 for chlorpyrifos-oxon) were conducted in replicate. Indivi dual experiments were conducted for chlorpyrifos photolysis kinetics/products (Experiment 1), chlorpyrif os photo-oxidation produc ts (Experiment 4), chlorpyrifos-oxon photolysis kinetics/products (Experiment 5) and chlorpyrifos-oxon photooxidation products (Experiment 8).

f) Controls were not described in the study outline. Conventional dark cont rols with air treated at the same application rate and incubated at the same temperature for the same duration as the irradiated samples were not utilized. Treat ed air samples were co llected during a 1.5- to 2.5-hour equilibration interval during which the chamber was held in darkness prior to sunlight exposure.

g) Test duration was not specified in the study outline. Air samples should be analyzed at four or more sampling time intervals with at least one observation made afte r one-half life of the test substance has degraded or 30 days, wh ichever comes first. FTIR spectra were continuously taken at a sampling time of 5 minutes/spectrum (p. 16). For chlorpyrifos photolysis, chlorpyrifos decreased from ca . 90 ppb at start of irradiation to ca . 40 ppb when the chamber closed (Figure 10, p. 33). For chlorpyrifos-oxon photolys is, chlorpyrifos-oxon

decreased from ca . 150 ppb at start of irradiation to ca . 90 ppb when the chamber closed,

then further decreased to ca . 75 ppb at the final sampling (Figure 32, p. 63).

h) Light source. The intensity of the experimental light should be compared to natural summer sunlight at 40oN. The EUPHORE is located in Valencia, Spain (39.5oN) and the experiments were conducted between September 6t h and 19th, 2011(p. 14; Annex 8.3, pp. 119-122). Photolysis frequencies and/or radiation were measured during the experiments, but not compared to natural summer sunlight at 40oN (Figure 5B, p. 27; Figure 7, p. 28; Figure 14, p. 39; Figure 19B, p. 44; Figure 27B, p. 58; Figu re 29, p. 59; Figure 35, p. 68; Figure 41B, p. 73). It could not be determined if the re duction in solar transmission (<20%) through the

chamber wall was considered in th e degradation rate equations.

2. The chlorpyrifos photolysis and photo-oxidation "p roducts" experiments were terminated before the pattern of formation and decline of chlo rpyrifos-oxon was established (Figure 10, p. 33; Figure 24, p. 47).

3. Limits of detection and quantif ication for methodologies other th an FTIR were not reported.

IV. REFERENCES

1. U.S. Environmental Protection Agency. 2008. Fate, Transport and Transformation Test Guidelines, OCSPP 835.2370, Photodegradation in Air. Office of Chemical Safety and Pollution Prevention, Washington, DC. EPA 712-C-08-014.Chlorpyrifos (PC 059101) MRID 48789701Page 19 of 26DER ATTACHMENT 1. Chlorpyrifos and Its Environmental Transformation Products.ACode Name/SynonymChemical NameChemical StructureStudy TypeMRIDMaximum ppb(day)Final ppb(study length)PARENTChlorpyrifosIUPAC:O,O-Diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioateCAS:O,O-Diethyl O-(3,5,6-trichloro-2-pyridinyl)phosphorothioateCAS No.:2921-88-2Formula:C9H11Cl3NO3PSMW:350.59 g/molSMILES:CCOP(=S)(OCC)Oc1nc(CL)c(CL)cc1CL835.2370Photodegradationin air48789701Photolysis:90(ca. 30 min)35(ca. 5.5 hr)TRANSFORMATION PRODUCTSChlorpyrifos oxonIUPAC:Diethyl(3,5,6-trichloro-2-pyridyl)phosphateCAS:Diethyl 3,5,6-trichloro(2,6)pyridine-2-ylphosphateCAS No.:5598-15-2Formula:C9H11Cl3NO4PMW:334.52 g/molSMILES:O=P(Oc1nc(c(cc1CL)CL)CL)(OCC)OCCClNPOHHHOHHHOOClCl835.2370Photodegradationin air48789701Photolysis:50(ca.5.5 hr)50(ca.5.5 hr)Photo-oxidation:40(ca.2 hr)40(ca.2 hr)Chlorpyrifos (PC 059101) MRID 48789701Page 20 of 26Code Name/SynonymChemical NameChemical StructureStudy TypeMRIDMaximum ppb(day)Final ppb(study length)Sulfur dioxideIUPAC:Sulfur dioxideCAS No.:7446-09-5Formula:SO2MW: 64 g/molSMILES:O=S=O835.2370Photodegradationin air48789701Photolysis:10(ca.5.5 hr)10(ca.5.5 hr)Photo-oxidation:20(ca.1.5-2 hr)20(ca.2 hr)OzoneIUPAC:OzoneCAS No.:10028-15-6Formula:O3MW:48 g/molSMILES:O=O=O835.2370Photodegradationin air48789701Photo-oxidation:30(ca.1 hr)10(ca.2 hr)Formic acidIUPAC:Formic acidCAS No.:64-18-6Formula:CH2O2MW:46 g/molSMILES:O=CO835.2370Photodegradationin air48789701Photo-oxidation:20(ca. 2hr)20(ca.2 hr)FormaldehydeIUPAC:FormaldehydeCAS No.:50-00-0Formula:CH2OMW:30 g/molSMILES:O=C835.2370Photodegradationin air48789701Photolysis:30(ca.1 hr)10(ca.5 hr)Photo-oxidation:20(ca.1.5-2 hr)20(ca.2 hr)AcetaldehydeIUPAC:AcetaldehydeCAS No.:75-07-0Formula:C2H4OMW:44 g/molSMILES:O=CC835.2370Photodegradationin air48789701Photolysis:5(ca.1-5 hr)5(ca.5 hr)Chlorpyrifos (PC 059101) MRID 48789701Page 21 of 26Code Name/SynonymChemical NameChemical StructureStudy TypeMRIDMaximum ppb(day)Final ppb(study length)PyridinolIUPAC:3,5,6-Trichloropyridin-2-olCAS:3,5,6-Trichloro-2-pyridinolCAS No.:6515-38-4Formula:C5H2Cl3NOMW:198.44 g/molSMILES:Oc1nc(CL)c(CL)cc1CL835.2370Photodegradationin air48789701Photo-oxidation:5(ca.0.5-2 hr)5(ca.2 hr)Peroxyacetyl nitrate(PAN)IUPAC:Peroxyacetyl nitrateCAS No.:2278-22-0Formula:C2H3NO5MW:121.05 g/molSMILES:CC(=O)OON(=O)=O835.2370Photodegradationin air48789701Photo-oxidation:1(ca.1 hr)<1 (ca.2 hr)GlyoxalIUPAC:EthanedialCAS No.:107-22-2Formula:C2H2O2MW:58.04 g/molSMILES:O=CC=O835.2370Photodegradationin air48789701Photolysis:NQNQPhoto-oxidation:NQNQMethyl glyoxalCAS:Propanal, 2-oxoCAS No.:78-98-8Formula:C3H4O2MW:72.06 g/molSMILES:O=CC(=O)C835.2370Photodegradationin air48789701Photolysis:NQNQChlorpyrifos (PC 059101) MRID 48789701Page 22 of 26Code Name/SynonymChemical NameChemical StructureStudy TypeMRIDMaximum ppb(day)Final ppb(study length)REFERENCE COMPOUNDS NOT IDENTIFIEDCYCLIUPAC:CyclohexaneCAS No.:110-82-7Formula:C6H12MW:84.16 g/molSMILES:C(CCCC1)C1835.2370Photodegradationin air48789701NA NASF6IUPAC:Sulfur hexafluorideCAS No.:2251-62-4Formula:F6SMW:146.06 g/molSMILES:FS(F)(F)(F)(F)F835.2370Photodegradationin air48789701NA NATMBIUPAC:1,3,5-TrimethylbenzeneCAS No.:108-67-8Formula:C9H12MW:120.19 g/molSMILES:c(cc(cc1C)C)(c1)C835.2370Photodegradationin air48789701NA NAAAR means “applied radioactivity”. MW means “molecular weight”. NQ means “not quantified”. NA means “not applicable”.Chlorpyrifos (PC 059101) MRID 48789701Page 23 of 26Table 2. Chlorpyrifos oxon and Its Environmental Transformation Products.ACode Name/SynonymChemical NameChemical StructureStudy TypeMRIDMaximum ppb(day)Final ppb(study length)PARENTChlorpyrifos oxonIUPAC:Diethyl(3,5,6-trichloro-2-pyridyl)phosphateCAS:Diethyl 3,5,6-trichloro(2,6)pyridine-2-ylphosphateCAS No.:5598-15-2Formula:C9H11Cl3NO4PMW:334.52 g/molSMILES:O=P(Oc1nc(c(cc1CL)CL)CL)(OCC)OCCClNPOHHHOHHHOOClCl835.2370Photodegradationin air48789701Photolysis:150(ca. 30 min)75(ca. 4.4 hr)TRANSFORMATION PRODUCTSSulfur dioxideIUPAC:Sulfur dioxideCAS No.:7446-09-5Formula:SO2MW: 64 g/molSMILES:O=S=O835.2370Photodegradationin air48789701Photo-oxidation:15(ca.1.5 hr)10(ca.3.5 hr)OzoneIUPAC:OzoneCAS No.:10028-15-6Formula:O3MW:48 g/molSMILES:O=O=O835.2370Photodegradationin air48789701Photo-oxidation:40(ca.3.5 hr)40(ca.3.5 hr)Chlorpyrifos (PC 059101) MRID 48789701Page 24 of 26Code Name/SynonymChemical NameChemical StructureStudy TypeMRIDMaximum ppb(day)Final ppb(study length)Formic acidIUPAC:Formic acidCAS No.:64-18-6Formula:CH2O2MW:46 g/molSMILES:O=CO835.2370Photodegradationin air48789701Photo-oxidation:25(ca.3.5 hr)25(ca.3.5 hr)FormaldehydeIUPAC:FormaldehydeCAS No.:50-00-0Formula:CH2OMW:30 g/molSMILES:O=C835.2370Photodegradationin air48789701Photolysis:10(ca.4.4 hr)10(ca.4.4 hr)Photo-oxidation:20(ca.2 hr)15(ca.3.5 hr)PyridinolIUPAC:3,5,6-Trichloropyridin-2-olCAS:3,5,6-Trichloro-2-pyridinolCAS No.:6515-38-4Formula:C5H2Cl3NOMW:198.44 g/molSMILES:Oc1nc(CL)c(CL)cc1CL835.2370Photodegradationin air48789701Photolysis:NQNQPhoto-oxidation:5(ca.1.5 hr)<5 (ca.3.5 hr)Peroxyacetyl nitrate(PAN)IUPAC:Peroxyacetyl nitrateCAS No.:2278-22-0Formula:C2H3NO5MW:121.05 g/molSMILES:CC(=O)OON(=O)=O835.2370Photodegradationin air48789701Photo-oxidation:NQNQHClIUPAC:Hydrochloric acidCAS No.:7647-01-0Formula:ClHMW:36 g/molSMILES:Cl835.2370Photodegradationin air48789701Photolysis:10(ca.4.4 hr)10(ca.4.4 hr)Photo-oxidation:10(ca.3.5 hr)10(ca.3.5 hr)Chlorpyrifos (PC 059101) MRID 48789701Page 25 of 26Code Name/SynonymChemical NameChemical StructureStudy TypeMRIDMaximum ppb(day)Final ppb(study length)Methyl glyoxalCAS:Propanal, 2-oxoCAS No.:78-98-8Formula:C3H4O2MW:72.06 g/molSMILES:O=CC(=O)C835.2370Photodegradationin air48789701Photolysis:NQNQPhoto-oxidation:10(ca.3.5 hr)10(ca.3.5 hr)GlyoxalIUPAC:EthanedialCAS No.:107-22-2Formula:C2H2O2MW:58.04 g/molSMILES:O=CC=O835.2370Photodegradationin air48789701Photolysis:NQNQAcetoneIUPAC:2-PropanoneCAS No.:67-64-1Formula:C3H6OMW:58.08 g/molSMILES:O=C(C)C835.2370Photodegradationin air48789701Photo-oxidation:NQNQREFERENCE COMPOUNDS NOT IDENTIFIEDCYCLIUPAC:CyclohexaneCAS No.:110-82-7Formula:C6H12MW:84.16 g/molSMILES:C(CCCC1)C1835.2370Photodegradationin air48789701NA NAChlorpyrifos (PC 059101) MRID 48789701Page 26 of 26Code Name/SynonymChemical NameChemical StructureStudy TypeMRIDMaximum ppb(day)Final ppb(study length)SF6IUPAC:Sulfur hexafluorideCAS No.:2251-62-4Formula:F6SMW:146.06 g/molSMILES:FS(F)(F)(F)(F)F835.2370Photodegradationin air48789701NA NATMBIUPAC:1,3,5-TrimethylbenzeneCAS No.:108-67-8Formula:C9H12MW:120.19 g/molSMILES:c(cc(cc1C)C)(c1)C835.2370Photodegradationin air48789701NA NAAAR means “applied radioactivity”. MW means “molecular weight”. NQ means “not quantified”. NA means “not applicable”.