Document km09wO44nYYGKk7L4kKv8JDQb

> - RECEIVED MAR 2 3 ...3 NEILSON ASSOCIATES CONSULTANTS - EPIOEMIOLOGY, INDUSTRIAL HYGIENE, OCCUPATIONAL medicine, toxicology 719 Pheasant Run West Chester, Pennsylvania 19380 Phone <215> 7931389 trch 21, 1978 Mr. Ivars Zvirbulis Fred S. James & Company 841 Chestnut StreetPhiladelphia, Pennsylvania 19107 RE: Certainteed Corporation Ambler, Pennsylvania Plant t t a.** n.. JDK UR f MW CR RAH UK Dear Ivars: INSURANCE/ INVESTMENT APR 0O 1978 RETAIN ln 3 v C VO * Ilf PERM Several specific comments are in order with reference to Mr. Benashski's Industrial Hygiene Report. These are as follows: 1. It was noted that both Mr. Benashski and Mr. Wilms made continual adjustments of personal sampling air pumps during the sampling period. One would wonder how they maintained calibration. 2. Several of the open-faced filter cassettes were pointed upward instead of downward. This is not good Industrial Hygiene practice. 3. Presence of ashes,,os fibre does not constitute a hazard to employee health unless the following criteria are met: a. The fibres are airborne and in quantities greater than 2 fibres per c.c. for an 8-hour work day. b. There .is continued exposure. 4. Swipe samples are not indicative of potential occupational exposure. The general population is exposed to asbestos fibre, i.e., from motor vehicle brake linings, asbestos in drinking water, etc. 5. Percentage of Free SiC^ in settled dust has no analytical significance in terms of airborne concentrations, and may veil contain 85-90& or higher non-respirable fractions. PLAINTIFF'S EXHIBIT CTD006783 NEILSON ASSOCIATES Mr. Ivars Zvirbulis Fred S. James & Company -2- March 21, 1978 6. Crusher Operation - 67 minute and 55 minute (2.4 and 5*3 fibres per c.c.) samples are not representative of 8-hour Time-Weighted Averages, i.e.. Travelers. Report 1/5/73 30 fibres per c.c. - approx. 4-1/2 hours 7* Mixing Operation - Again 13 minute and 64 minute (3.4 and 2.8 fibres per c.c.) samples used as an 8-hour TWA and is not a true representation, i.e., Aetna Report 12/8/76 .23 fibres per c.c. - 2 hours .21 fibres per c.c. - 2 hours 8. Rework Saw - Again a breathing zone sample of 50 minutes (0.6 fibres per c.c.) does not constitute an 8-hour TWA, i.e.. Travelers Report 1/3/73 0.6 fibres per c.c. - approx. 3-1/2 hours Aetna Report 12/8/76 0.0 fibres per c.c. - 2 hours 0.0 fibres per c.c. - 15 minutes 9. Lehman Short Lathe - Again 1-1/2 hours (3*9 fibres per c.c.) is not a true TWA, i.e., Travelers Report 1/3/73 .11 fibres per c.c. - approx. 4-1/2 hours Aetna Report 12/8/76 1.0 fibres per c.c. - approx. 3 hours 1.9 fibres per c.c. - 15 minute peak 10. The paragraph (pg.9, para. 2) "Though all operations tested had exhaust ventilation, some of the piping had holes in it, the workers tended to lean into the exhaust air and dust did settle around areas of poorly designed exhaust systems." is contradictory, and exhaust system by its nature sucks inward and would not discharge fibre to the operator. 11. Without the tare and gross weights and the correction factor for the reference PVC filters it is difficult to check or follow the calculated values reported. CTD006784 NEILSON ASSOCIATES Mr. Ivars Zvirbulis Fred S. James & Company -3- March 21, 1978 In summary, this report cites as its basis for standard comparison short term samples and only those samples where one might expect short term high fibre counts were taken. However a review of previous Industrial Hygiene Reports made by both the Travelers and the Aetna Insurance Companies are significantly lower in fibre per c.c. and are also of longer sampling duration. I hope that this summarization is satisfactory. If you have any comments please advise. Sincerely AN/sn Arthur Neilson Industrial Hygienist CTD006785