*** Regarding the vapor degreaser discussion problem, I thought it was a good discussion. I did not have a "right" answer in mind, but wanted you to explore the issues, which you did very well. With very inert gasses, often the greatest hazard is "simple asphyxiation" from lack of oxygen. That is, the gas displaces air. Air is about 21% oxygen. A healthy person can perform most activities down to about 19% oxygen. Below that, problems can come very quickly. Even a healthy person can quickly become unconscious at oxygen levels below 17%. (At sea level. At altitude and depth, the numbers are different.)
***Q What does EC50 mean? I ran into it on the HSDB database (off of Toxnet)?
A. LD refers to oral exposures, LC, for Lethal Concentration, refers to inhaled exposures. ED and EC are used if the endpoint described is other than death.
**Q. The only thing I didn't understand - why if the exposure at workplace exceeds all the limits no one is under obligation to change the situation?
A. Good question. You learn in a later module that you protect the workers first by eliminating the problem via engineering controls, then by eliminating the exposure via administrative controls, and lastly by PPE. However the law only requires the PPE. So cost dictates that if engineering controls or administrative controls are too expensive, PPE will be resorted to. Part of the problem comes from the legal concept of a "bright line." That is, a definite number that separates the legal from the illegal. Such a number is straight forward for human exposure. For engineering controls, it is more difficult to establish what is reasonable. We will cover this again in air and water pollution, where such engineering standards are set. You will see that they are rather subjective.
**Q. The muddiest issue for me was your statement about ethical industrial hygienists always working to the NIOSH standards.
A. It says to work to the TLV, which are ACGIH, not NIOSH. {How's that, three acronyms in 12 words. Sorry} NIOSH standards, known as RELs are often too conservative, in the opinion of many health and safety professionals, including me.
** Q. Something I found incomplete: Why doesn't American Conference of Government Industrial Hygienist publish a universal MSDS instead of there being so many different ones out there that say basically the same thing.
A. MSDS came about because of a requirement for chemical manufactures and sellers to provide the information. ACGIH does not have the resources to do anything like that. They only have 500 or so TLVs out of the 30,000 or so chemicals that are common. Not to mention the uncommon chemicals. So basically, only the companies that are selling chemicals for a profit need to spend the money to write the MSDS. But be sure to remember that those companies do not have to do any testing of the chemical for the MSDS, only look up and report known data. It is perfectly legal for them to write "unknown" or "not available" for any item on the sheet, providing it is indeed unknown or unavailable.
* Q. In the Karen Wetterhahn case why didn't she have the slightest idea of the mercury being absorbed in the skin and if she did then why didn't she see a doctor. Because generally I would think that any research chemist would have a good idea about the chemical he/she is dealing with (its dimethyl mercury). I would not assume that it was a case of utter negligence.
A. It's an interesting story. Please see http://www.udel.edu/OHS/dartmouth/drtmtharticle.html for a good explanation. But amazingly, the answer was "ignorance," at least of that particular chemical. She was an expert in the toxicology of many chemicals, but of this one, she was unaware. There are 30,000 or so chemicals in commercial use. It's impossible to know more than a few of them well.
* Q. It is my understanding that OSHA is allowed to enter workplaces with little or no advance warning. Companies are then fined for not following regulations. My question is what happens when companies just don't care about fixing the problems but still pay the fines? It seems that it makes it almost OK if a company can afford to pay the fines but not correct the reason they are getting the fines. Plus, it seems that these companies should have more unions or workers who care about the OSHA regulations.
A. The proposed fines are typically very stiff, then OSHA's attorney offers to drop it to something reasonable. It's not uncommon for the proposed fine to be $100,000 and the actual $10,000. But for "willful" or "repeated" violations the price goes way up. There are also criminal penalties, seldom used, but available. Also, although OSHA will not admit it, they have a "bad list" of companies that are more likely to be inspected, usually because they have been callus in the past. Also, again OSHA will not admit it in public; most of their inspections are triggered by worker complaints.
*Q. From the Workplace Health section. You stated that the A1, A2, A3, and A4 notations in the TLV listings refer to the carcinogenicity of the compound. A4 means unclassified, A1 means human carcinogen. What do A2 and A3 mean?
A. Group A2: Suspected Human Carcinogen ; Group A3: Confirmed Animal Carcinogen with Unknown Relevance to Humans
*Q. Some more information about the TLV book would have been nice since it seems to be an industry standard.
A. Yes. Unfortunately for us, it is copyrighted and I can't just put it on the web site. They are available for sale from ACGIH. Anyone in the safety and health business should have one.
* Q. I honestly had no idea that the TLVs were recommendations only, and that only the PEL was the law to which an employer could be held.
A. Yes. Now a government can adopt the TLV's as the law, as some foreign governments have done and as OSHA did in 1970, but as written, the TLV's are only recommendations.
Q. I am a bit confused at why the Occupational Safety and Health Act of 1970 established both OSHA and NIOSH. To me, this seems redundant. From their mission statement I gather that their main job is to inform, but I don't see why they are separate from OSHA.
A.
Strictly politics. Congress felt that anti-business types in the Department of Labor would set unreasonable standards, so they put NIOSH in the Public Health Service, where it would be isolated from politics. However since NIOSH can't set any regulations, all that does not matter. Besides, it turns out that NIOSH make recommendations that are usually much stricter than OSHA's. Also, NIOSH has a very small budget compared to OSHA
Q. Is Asbestos hazardous? , A lot of asbestos is used in the construction of WTC, after its collapse asbestos mixes in the air and so how far is this asbestos hazardous and does any organization post any regulations?
A. Asbestos is one of the most highly regulated substances. Both EPA and OSHA regulate it. Airborne asbestos fibers are one of the most toxic substances worker are exposed to.
Q. The whole section on how to measure exposure [monitoring] was a fog for me. I read and re-read the websites and the book. It seemed a bit much for me. I was difficult for me to read these and decipher what I should know about "methods" and "products". The book was okay on generalities but the websites got into minutiae pretty quickly so it made it hard for me to figure out what I was suppose to understand from the websites. Perhaps it wouldn't have been so foggy if the chemicals we were investigating were something we could more easily find on the sampling guide lists.
A. For an undergraduate degree in industrial hygiene, the students have at least a three-credit course in this, plus a laboratory. Don't be amazed you can't get the whole thing in a week. One thing that might add to the confusion is that neither the ACGIH nor OSHA specifies, for most substances, exactly how to measure them. That is up to the employer. NIOSH is more specific and publishes detailed procedures, but NIOSH recommendations tend to be the most stringent, and are often avoided. All these agencies are reluctant to specify brand names. Going the other way, however, the vendors will always tell you their products are good for the pertinent regulations or have been accepted by OSHA, or whoever.