"a measurement method that can only go down to 560 ng/m3 raises the possibility that you would miss levels that are above the action level of 500" Dr. Bob Herrick

"The significance of this would be that the levels found at the buildings at U Rhode Island and U Mass, both of which were highly contaminated and had full EPA approved remediations done, would have mostly been measured as nondetectable using the method that as apparently used in the NY schools." Dr. Bob Herrick

Certainly any laboratory that cannot detect 10 ng/m3 might just as well not do the measurement, because the results are meaningless. Dr David Carpenter

Read the following from Dr. Bob Herrick from Harvard and Dr. David Carpenter from the State University of Albany regarding the NYC public schools PCB air sampling

One thing I would point out is that the limit of detection for the air samples is not very sensitive. These measurements could go as low as about 500 ng/m3. The studies done at places like University of Rhode Island and University of Massachusetts could measure levels down to about 50 ng/m3. The difference is probably in the length of time the air sample was taken. The longer the sample time, the greater of volume of air sampled, and the lower the detectable amount of PCB measured.

The significance of this would be that the levels found at the buildings at University Rhode Island and University of Massachusetts, both of which were highly contaminated and had full EPA approved remediations done, would have mostly been measured as nondetectable using the method that as apparently used in the NY schools. The NIOSH recommeded exposure level is 1000 ng/m3, and anything above half that (500 ng/m3) would be considered above the action level, meaning that further investigation is needed.

So a measurement method that can only go down to 560 ng/m3 raises the possibility that you would miss levels that are above the action level of 500. Dr. Bob Herrick 4/6/2008

Dr. Bob Herrick
Harvard School of Public Health
Phone: 617- 384-8803
Fax: 617-384-8859
Email: herrick@hohp.harvard.edu

 

The levels of PCBs in normal outdoor air is 1 ng/cubic meter of air. Any laboratory that cannot determine 1 ng/m3 is not worth much, since even relatively small elevations are going to be associated with inhalation exposure. Certainly any laboratory that cannot detect 10 ng/m3 might just as well not do the measurement, because the results are meaningless. When a person breathes in air, the PCBs will primarily dissolve in the fat of the cells of the lung, so a person will be exposed to whatever level is in the air. David Carpenter MD 4/7/2008

David Carpenter MD
Institute for Health & the Environment
University at Albany, SUNY
5 University Place, A217
Rensselaer NY 12144
Tel: (518) 525-2660
Fax: (518) 525-2665
Email: Carpent@uamail.albany.edu