MEMORANDUM 

TO: Nhan Nguyen 

 

FROM: Maj’d El-Zoobi 

 

DATE: December 2, 2008 

SUBJECT: Review of Inhalation Monitoring Study for the of P-07-601 

The submitter of P-07-601 submitted the subject matter study as an alternative assessment to 

CEB’s assessment of inhalation exposure at the of P-07-601. 

The review of this study was tasked to ERG’s industrial hygienist who was provided with 

guidelines for conducting the review that are based on your directive on this matter which you 

sent to me on 8/12/08. 

This memorandum contains the subject matter, which includes the following items: 

- a brief presentation of the results of the study; 

- a summary of ERG’s review comments on the study; 

- a summary of my comments on the study; 

As further discussed below, I assess the submitter’s study to contain some significant 

transparency flaws, and to possibly be deficient in regard to the number of samples taken. These 

concerns may be addressed through discussion with the submitter, and likely additional 

monitoring. 

The recommended alternative path forward is to maintain CEB’s assessed average and maximum 

values of ppm and ppm respectively in lieu of additional monitoring. It is noted that the 

average value of ppm is comparable to the highest average exposure level reported in the 

submitter’s inhalation monitoring study, which is ppm, which supports the use of ppm as a 

valid assessed value. The assessed maximum value of ppm is maintained even though it 

significantly exceeds the level of ppm because there is uncertainty in the results of the 

submitter’s inhalation monitoring study. This maximum value is an TWA value. 
Presentation of the Results of the Study and Comparison With the Current Assessment: 

Inhalation Exposure Concentration Assessed Values 

CEB’s Current Assessment Submitter Inhalation Monitoring 

Study 

Worker 

Activity 

8 hr TWA 

Exposure 

concentration 

(ppm) 

Comments 8 hr TWA 

Exposure 

concentration 

(ppm) 

Comments 

 

 

Other Available Inhalation Exposure Concentration Data 

Worker 

Activity

CEB Data Submitter Data 

 

Personal 

samples 

 

Note (1): Table A-6, “Summary of Personal Occupational Exposure Monitoring Data for 

Manufacture of ”, Occupational Exposure And Environmental Release Data for and Their 

Substitutes, PEI Associates, 1990. 

The vapor pressure and boiling point of (the GS basis), mmHg and C, are 

comparable to the corresponding values for the NCS, which are mmHg and C, 

respectively. Hence the GS data is valid for comparison purposes. 

Note (2): These two data points, the exposure levels for , which is ppm, and the 

exposure level for the , which is ppm, may be discarded because they appear to 

be for specific job functions in the manufacture of that do not have an equivalent in the 

manufacture of the new chemical. 

Summary Of ERG’s Review Comments On The Study:

The following is excerpted from ERG’s report on their review of the study. The complete ERG 

report is attached at the bottom. 

Summary of Limitations: 

• Additional monitoring should be conducted to account for the exposure variability 

associated with the work environment and random sampling and analytical errors. 

Specifically, a total of at least six full-shift personal breathing zone (PBZ) samples should 

be collected over six different days to adequately characterize worker exposure to the two 

refrigerants. 
• Information regarding the daily duration of exposure should be provided according to 

individual job titles, including a total number of workers by each job title that could 

potentially be exposed to these two chemicals. 

• Exposure criteria for workers at both facilities have been based on an work shift 

but the possibility of workers working shifts which could exceed the shift 

duration has not been considered. 

• The study does not indicate the total number of workers by each job title that could 

potentially be exposed to the two refrigerants. 

 Additional information to incorporate into the monitoring study/report for completeness 

includes: 

oThe manner in which the number of samples collected was determined. 

oThe manner in which the number of workers to be monitored was determined. 

oThe reason specific job classifications or specific individuals were selected for 

monitoring. Typically, workers with the greatest potential for exposure must be 

included. 

• The study does not provide information on whether there may be other tasks with the 

potential for worker exposure; e.g., tasks performed by workers that might be involved 

in non-routine activities.

• Exposure criteria for workers at both facilities have been based on an work shift but 

the possibility of workers working shifts which could exceed the standard shift 

duration has not been considered. 

• No information was available from the report on variables such as: 

o The age of the plant. 

o The age of the control equipment. 

o Operation and maintenance (O&M) practices at the plant. 

o Production levels. 

• The monitoring report includes no discussion regarding the occupational exposure limits 

(OELs) for and . Further, the study fails to discuss the monitoring results by 

comparing them to the OELs for the two . 

• Personal protective equipment (PPE) worn by the workers sampled, if any, was not 

identified in the report. 

Summary Of My Comments On The Study

The report does provide a description of plant operations worker activities, but it does not clearly 

indicate whether there are other tasks that may result in exposure levels that are higher than what 

was sampled. 

Also, the report does not consider exposure of workers.