Module 2
**Q. How long is a "long paragraph?" Maybe, my assignment is too short. I will see it. A. No, it is just fine. I try to give an idea of the length, because some students feel they have to write 8 or 10 pages, while another feels one sentence is sufficient.
*Q. Is it required (by law!), to provide the MSDS and the proper training in
an understandable language for the employee?
A. Very important point. I teach more about worker protection in ENVE 649, Hazardous
and Toxic Waste Management. Briefly, it is the employer's obligation to sure
each employee understands the hazards. The problem is that the employees will
insist they understand English, when they may not. Also, without proper training,
how will an English-speaking employee know who IARC is? Or what "hepatotoxic"
means?
*Q. I have had basic organic chemistry presented I don't know how many times
and I still get the names messed up. Have you ever seen a good one or two page
cheat sheet/reference? They are inside the front cover of many organic chemistry
textbooks.
A. Here's one from the web:
http://www.wikipedia.com/wiki/functional+group
*Q. According to US law: do scientific research or medical institutions have
to report the newly obtained data on chemical's toxicity? If yes, where? To
whom? Or is it a requirement for manufacturers to carry such research?
A. No they don't. When a manufacturer markets a new chemical they must prepare
an MSDS sheet, but they do not need to do any research on it. They have a legal
liability if anyone gets hurt; so most manufacturers do some investigation.
Many new products are mixtures of several chemicals, and the properties of these
constituents are known. These will be on the MSDS sheet. Medical or scientific
labs might discover something but they are not required to report their discoveries.
*Q. In general words, how will I, common person, know how toxic might be a
simple household chemical, if a manufacturer provides old data?
Consumer products, those that you buy in a supermarket, come under the Consumer
Product Safety Commission regulations. These require labeling of toxicity, but
only in the very general way. You will see most labels have an 800 number or
address for more information, but I have not had any luck getting real toxicity
information by this route. Most commercial products by major manufactures have
been tested pretty well. The chemicals you use in the laboratory are not consumer
products and do not need to be labeled.
*Q. I finally went to the department homepage that states that MSDS sheets
should be obtained from the manufacturer for any chemical used in the lab. Based
on the limited information in the database, this is a great idea, but they should
not represent their database as containing MSDS info.
A. There is worker-OSHA issue in that statment. In the US you are allowed to
use CD's and MSDS's from the web to inform your employees, but they have to
be trained in this and the system must be readily available. You can't just
tell employees, "you can find it on the web."
*Q. In addition to same MSDS sheets the companies or manufacturers mention
about the purity of the chemical they are selling.
A. Because they don't have to. But that brings up an important point, often
a minor impurity from a chemical standpoint, might be the major factor from
a toxicological standpoint. 2,3,7,8 TCDD is a minor impurity of "agent
orange" but was allegedly responsible for many effects.
Q: Are the rate of organic reactions generally faster or slower compared to
the rate of inorganic reactions and why?
A. They are so variable that you could not categorize reaction rate by organic
vs. inorganic. Most reactions rates are temperature dependent and biological
reactions are limited to a narrow range of temperatures.
Q. Why don't companies and manufacturers follow one particular guideline for
MSDS sheets for their products ?
A. They do, but the guideline, the OSHA regulation, is very broad.
Q. Do the majority of toxics affect tissue and organs or the CNS?
A. The CNS, central nervous system, is a branch or department of the organ system
known as Nervous System. Most such branches of other organ systems are separate
organs. For example the pancreas and liver are separate organs in the GI system.
The CNS is really just one organ and the "system" part of the name
is somewhat a misnomer. Almost all toxics that are interested do their damage
at the cellular and biochemical level of organization. The "clinical significance"
on the other hand, comes when this damage to individual cells becomes significant
to an organ or organ system.
Q. That Tissues, Organs, Systems, Signals and Receptors Submodule seems like
it could have been a whole lesson in and of itself. Do you have a eukaryote
point of view on organelles?
A. Only eukaryotes have "membrane bound" organelles. Prokaryotes do
have ribosomes.
Q. Also, are unsaturated oils better for you because of the physical properties
(ie the slipperiness and shape) or because of the chemical properties (the double
bond that may allow something)?
A. Both, but many of the details are beyond me. Note the location of the double
bonds is apparently very important.
Q. In light of these different styles and qualities, was there a regulatory
change at some point in the 1990s that dictated a uniform style to MSDS's.?
A. No. The ANSI standard is still voluntary. The ANSI standard was developed
in 1993, long after the HAZ COM law, so some major players did not have theirs
in ANSI format. They would also object to a change in the standard.
Q. Finally, have there been any proposals to establish regulatory oversight
and review of MSDS quality, such that an incomplete MSDS would require rewriting
if a review deemed it inadequate?
A. Not as far as I know. It takes a major push and about 10 years to change
an OSHA regulation.
Q. I am very disturbed by the story of Dr. Wetterhahn. If DMM is that lethal,
it seems to me that there should have been some very extensive training for
not only Dr. W., but for everyone who worked in that lab and may have had the
opportunity to come in contact with DMMe~. If the chemical was so dangerous,
why didn't anyone know or tell Dr. W. about the latex gloves? Dr. W. was experiencing
symptoms- shouldn't she have been under a special medical surveillance program?
If she were working with radioactive isotopes, she would have been forced to
wear film badges, protective clothing and get her thyroid checked twice a year.
Was this just a fluke incident of compounding errors, or is there potential
for similar incidences that we are not aware of?
A. Her employer, Dartmouth, was fined by OSHA. Training is a difficult issue
in this case because Dr. W probably was the local expert on DMMe. Gloves and
other backup systems are not tested until there is a mistake. She may simply
have not spilled any on herself in the past. Her symptoms did not occur until
several weeks after the exposure. This is an extreme case. In this tox class
we have to break off learning about worker protection at some point, in the
Hazardous and Toxic Waste course (ENVE 649) we spend much more time on those
topics.
Q. In chemical engineering, the term kinetics is associated with how fast reactions
occur and is invariably tied up with differential equations. I recall that this
is also the case in biological reactions e.g. the Michaelis-Menten equation.
Does toxicokinetics also rely on this mathematical approach?
A. Yes, We assume each compartment is a well-stirred continuous flow reactor.
Elimination goes on in one or two selected compartments; this may be first order,
M-M, or whatever. The compartments are linked by first order differential equations.
Chemical engineers make good toxicokineticists.
Q. Just as an interesting note: Secondary and tertiary amines can also act
as weak acids because the N-H proton can be removed by a strong base. For example
the production of Lithium diisiopropylamide from Butyllithium and diisopropylamine
(Organic Chemistry, McMurry).
A. McMurry is my textbook too. The key is "strong base" most biological
bases and acids are weak. But thanks for the fine point.
Q. What is special about the composition of nerve tissue that makes it a good
conductor of electrical impulses - at least more so than other tissues?
Q. It's specialized for that, and only that. Nerve cells (which are called neurons)
that are designed to transmit long distances have insulating cells around them,
called Schwann cells. We'll talk a little more about that in a few weeks.
Q. I was wondering if the [p] designation in the chemical name dibenzo[p]dioxin
signifies the "para" orientation of the oxygen molecules to the chlorine
atoms on the benzyl rings of the compound. In dibenzo[b,e][1,4]dioxin, what
does the [b,e][1,4] indicate?
A. Go here: http://www.chem.qmw.ac.uk/iupac/fusedring/app2.html
and look at item 63 and note l. [p] for para would take care of one of the para
connections, but not the second.http://www.chem.qmw.ac.uk/iupac/fusedring/app2.html.
Q. What are/is the chemical receptors on the cell that the dibenzo[p]dioxins
target?
A. We will do a little more on that, but it's called the Ah receptor, it seems
to affect DNA quite a bit in some species, but no one is quite sure what the
"natural" function of the Ah receptor was or why there is such an
enormous species difference in it.