Memorandum on asbestos wipe sampling and cancer risk estimation, December

NYC 9/11 Public Portal Document

vendors), specially filtered particle-free water, dust free disposable gloves, and a high purity alcohol. The laboratory that will perform the actual test typically will work with you to get you these supplies.

Finding a Laboratory

First, choose a laboratory x hich is accredited by the EPA to perform'TEM (transmission electron microscopy) asbestos analyses. These labs are posted on the web at: http://ts.nist.gov/ts/htdocs/210/214/scopes/temtm.htm. Or, contact the National Institute for Standards and Technology (NIST) Laboratory Accreditation Administration, Gaithersburg, MD 20899 (telephone 301-975-4016). There are about 60 accredited labs. Since wipe samples cannot be used for regulatory purposes, it is irrelevant whether the lab also has an accreditation in New York State. You can use any out-of-state lab that is convenient. I Using TEM instead PCM analyses is important in terms of comparison of the wipe sample with I the TEM air level testing required under the asbestos AHERA standard. It is particularly important to use TEM for the WTC dusts because the asbestos in them is very fine. A PCM analysis will only detect larger particles. I Contact the lab to see what type of wipe samples they are capable or willing to perfonn. Ask whether they will perform TEM analyses on samples that were collected by American Society of Testing and Materials (ASTM) wipe Method D 6480 (wipe). Ask advice on sample preparation, handling, etc. I Interpreting the results of settled dust levels, wipe samples or microvacnum samples

Industrial hygienists and other health professionals recommend professional asbestos abatement procedures when a wipe sample is over the detection limit, or background, of 260 s/cn? for wipe samples, or over 1000 s/cm’ for a microvacuum sample.

If there are any elevated levels of asbestos on surfaces, then landlords should be contacted and asbestos abatement by trained, certified professionals should be instituted. Also, contact health and environmental agencies and elected officials so that they are aware of the problem and can provide assistance and intervene to provide assistance to others in the area who are probably contaminated as well. Contact local non-profit environmental and occupational safety and health organizations as well for assistance and advice.

PREDICTING AIR CONCENTRATIONS FROM SETTLED DUST LEVELS

To predict the amount of asbestos which will be in the air from a given settled dust level is not an exact science. Until such time as adequate air monitoring is available, the following may be the only viable method. Settled asbestos dusts get resuspended into the air inside buildings as the result of activities such as sweeping, walking around, moving heavy equipment, etc.

What is needed are factors, or numbers, to multiply the settled dust levels by to estimate the airborne levels. The following presents such a methodology. First, the conversion factors for an

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