Ten years after this national disaster adverse health effects suffered by people exposed to the dust clouds generated by the collapse continue to be documented.

The September edition of “The Lancet”, one of the oldest and most respected peer-reviewed medical journals is dedicated to three studies of first responders to the emergency.


The first study followed 9,853 male firefighters whose cancer incidence both before and after the attacks. They also studied cancer rated among unexposed firefighters.
o WTC exposed firefighters had 263 cases of cancer compared to 135 in the non-exposed group. Statistical studies of a similarly sized group of the general NYC population would predict 161 cases in the non-exposed group. Researchers feel that firefighters in general are healthier and less likely to smoke, explaining the lower incidence.
o This indicates that exposed firefighters have a 10% greater chance of developing cancer than the general population and a 19% greater chance than non-exposed firefighters. The authors feel that this is probably a result of carcinogens entrained in the dust clouds generated by the collapse.


The second study followed 27, 449 rescue workers. The researchers tried to weight the data by days at the site and exposure to the dust cloud. In particular, there was originally concern that the alkaline nature of the dust cloud could cause respiratory disease. Within the next 9 years following exposure, the following rates of incidence occurred with the incidence generally increasing along with exposure.
o Asthma – 28%
o GERD – 39%
o Sinusitis – 42%
o Spirometric Abnormalities – 42%


The last study unexpectedly found that all-cause mortality rates among rescue workers and civilians involved in the WTC attacks had lower death rates than a general sampling of the NYC population. People involved in the attacks who were registered in the WTC Health Registry had a 43% lower mortality rate than the general population. Researchers explained these findings as follows:
o People who were involved in the attacks tended to be employed. Employed people tend to be healthier than the overall population.
o Voluntary participants in studies such as this tend to be healthier than the general population.
o Many of the expected diseases resulting from exposure have a long latency and survival periods. The researchers expect the death rate to increase among people exposed over time as opposed to the general population.

The authors of all the studies emphasize the need for continued monitoring of the people exposed during the attacks. As the exposed population continues to age, the effects of the exposure are expected to become more apparent.

The most common methods used to analyze air samples taken to evaluate metal exposures are NIOSH 7300, OSHA ID-121, and OSHA ID-125. These methods involve taking the samples using a mixed cellulose-ester filter followed by digestion using a mixture of mineral acids. The digestions are used to reduce and solubilize the metals to their elemental state, after which the samples are subjected to spectrographic analysis using Atomic Absorption (AA), Inductively Coupled Plasma (ICP), or Inductively Coupled Plasma/Mass Spectroscopy. It is essential that the metals be in solution and in their elemental state for these analyses to be accurate.

The digestion procedures included in these methods are acceptable for the vast majority of exposure assessments, such as welding fumes, where the heat of the operation vaporizes the metals. Other operations such as grinding sometimes involve metallic compounds and alloys for which the digestion procedures either will not break the chemical bonds involved or will not solubilize the metals. This will cause the results obtained by analysis to be understated. An example of this type of compound is tungsten carbide. OSHA ID-213 has been specially developed to address this problem. It uses a decision tree within the method to determine the type of digestion required based upon the specific type of tungsten present in the material being tested. If you are sampling carbide compounds, it is important to take these samples separate from other metals you need to have analyzed and to let the laboratory know. Once a digestion has started it is difficult to stop and start over.

Other exotic alloys may present similar problems. If you encounter such alloys when researching an exposure assessment, I would highly recommend that you give the lab a call to make sure that the methods routinely used to analyze metal samples are able to break down and place the metals of interest into solution, thereby giving you the valid data needed to evaluate exposure.

Caulking materials manufactured between 1950 and 1978 are known to sometimes contain PCB’s. During building renovation, dusts containing levels of PCB’s can be generated. This is especially important for schools, where levels above the EPA’s recommended Public Exposure Limits for Schools (see below) can sometimes occur due to building contamination caused by material deterioration or poor maintenance techniques. A secondary concern is that buildings built during this timeframe are nearing the end of their economic usefulness. The demolition of these buildings will call for an extra level of care in order to avoid improper disposal of PCB containing hazardous waste.
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Public Health Levels of PCBs in School Indoor Air (ng/m3)
Assuming a background scenario of no significant PCB contamination in building materials and average exposure from other sources, these concentrations should keep total exposure below the reference dose of 20 ng PCB/kg-day.
Age:
1-<2 yr - 70 ng/m3
2-< 3 yr - 70 ng/m3
3- <6 yr - 100 ng/m3
6-<12 yr - 300 ng/m3
(elementary school)
12-<15 yr - 450 ng/m3
(middle school)
15-<19 yr - 600 ng/m3
(high school)
19+ yr - 450 ng/m3
(adult)
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On September 25th, 2009 the EPA issued a guidance document for school administrators outlining actions that should be taken to minimize toxic exposures to schoolchildren from PCB’s. These include initial actions to be taken to minimize potential exposures until it can be determined if PCB’s are present, recommendations for testing of air and caulking materials, and guidance for remediating identified contamination. The EPA considers the caulk to be PCB containing and regulated as hazardous waste if it contains more than 50ppm PCB’s. It’s important to note that if the caulk has significantly deteriorated, contamination of nearby surfaces and soil may have already occurred.

Careful planning of the removal of the contaminated caulk is required to insure that workers are protected and that no further contamination of the building takes place through the generation of dusts.

The two links below will take you to EPA web pages concerned with this issue:
http://www.epa.gov/pcbsincaulk/
http://www.epa.gov/epawaste/hazard/tsd/pcbs/pubs/caulk/caulkcontractors.htm

Nanotechnology is the manipulation of matter on a near-atomic scale to produce new structures, materials and devices. This technology promises scientific advancement for many sectors such as medicine, consumer products, energy, materials and manufacturing. Nanotechnology is somewhat loosely defined, although in general terms it covers engineered structures, devices, and systems that have a length scale between 1 and 100 nanometers. At this size, materials begin to exhibit unique properties that affect physical, chemical, and biological behavior. Researching, developing, and utilizing these properties is at the heart of new technology. Studies have indicated that low solubility nanoparticles are more toxic than larger particles on a mass for mass basis. There are strong indications that particle surface area and surface chemistry are responsible for observed responses in cell cultures and animals. There are also indications that nanoparticles can penetrate through the skin or move from the respiratory system to other organs. Research is continuing to understand how these unique properties may lead to specific health effects. Much research is still needed to understand the impact of nanotechnology on health, and to determine appropriate exposure monitoring and control strategies.

The above information was taken from the NIOSH website and is an overview on nanotechnology.

Currently there are 2 OEL’s that pertain to nano size particles – TiO2 and carbon nanotubes. I am sure that there will be many more OELs dealing with nano size particles in the near future and we as Health and Safety Professionals must be prepared to understand and deal with them.

To help you get statred and learn more about this new and exciting field, NIOSH has put together a list of frequently asked questions. Please follow this link to the questions and answers and stay current with what is happening with nanotechnology.

http://www.cdc.gov/niosh/topics/nanotech/faq.html