Administrative:
Q. I did purchase the recommended text. Will you be letting us know when to
read from it? Or should we read the first 4 chapters with the first 4 modules?
A. I'll try to keep you informed. But no, there is not a one to one correlation
between the book and the modules.
Q. In the closure, one question had two parts to it involving whether the modules
will stay online after the deadline passes or will it be inaccessible. The answer
was "Yes" but it is unclear to which question "Yes" was
the answer to.
A. Modules stay on line for the length of the course.
FROM Spring 2013
***Q. Sub module 1E Dose Units-Contaminants in air- You mention testing for solid contaminants with a filter test. What procedure is used when measuring contaminant gas in air?
A.
Instead of trapping on a mechanical filter, the gas must be trapped chemically. Charcoal is the chief absorbent of organic chemicals and is often used for that purpose.
***Q. In the introduction to toxicology we were introduced to a lot of terms, but not the LOEL value. Is there a reason for this? Is it not used in risk assessment? Do we rather concern the low ED values?
A. It depends on who is using it for what. The “C” in “LC” refers to concentrations in water or air, while the “D” in “LD” refers to dose given directly. The “L” in LOEL could be either concentration or dose, but would be consistent within the discussion.
**Q. Often, industry and environmental advocates differ in opinion and may use similar studies to emphasize opposing points. A current example may be Pebble mine. Let’s say the Cheech beer example applies to fish affected by water contaminants due to a future mine. Would two opposing groups agree on values such as NOEL, LD50, ED10, etc.? Who is correct?
A.
They would agree on the laboratory data. However that data is just that, “laboratory.” The relevance of the lab data to the environment is what they would argue about. Also, the likely hood (risk) of its release into the environment.
** Q. How was 14 days settled upon as part of the “highly toxic” definition? I don’t know.
A. It is a law, not science. Science often uses “96 hours” for the acute tests. That could be more scientific, but 96 hours is four days – get it up and running by noon Monday and take it down at noon on Friday, have the weekend off.
** Q. I am thinking it might be based on life history/biology of rats, about fair testing time frames, or something about the nature of toxins in all animals. Maybe just a fair compromise? I could ask the same question about other standards, but we have seen effects from exposure to substances like agent orange or radiation take years to realize.
A. Yes and you now realize the infinite combinations of species, test doses, and exposure time. So some standards become more or less accepted, and that’s the best we can do. There are even some multi-generational test protocols.
OLDER Closures
***Q. This is similar to the use of DDT. It is my understanding that DDT is
still used in places, like Africa, to reduce the chances of malaria. It is a
very difficult decision to make to weigh the risk of DDT vs. malaria as well
as DDT's reduced effect on the mosquito. Would this be an appropriate use of
risk assessment and risk management?
A. The use would be a risk management decision, based on the risk assessment
and other factors.
***Q(uestion). 2005. Are there any standardized toxicology tests that are used
to determine the effects from more chronic exposure (such as exposure that accumulates
in the process of bioaccumulation)?
A(nswer). Yes, especially for cancer effects, the tests are run over the lifetime
of the animals (about two years). Depending on the chemical, the body burden
might increase through the lifetime, thus accounting for bioaccumulation, although
that is often a separate issue.
**Q. In the article Death from Lab Poisoning, "methyl mercury used to
be a popular crop fumigant." Is this still used as a crop fumigant? If
so, has there been any ecological adverse health response?
A. There is a big difference between methyl mercury with is a serious contaminant
(Minamata) and dimethyl mercury which is very deadly (Wetterhahn). A variety
of mercury compounds were used on crops, some of which would be converted to
methyl mercury. I doubt dimethyl mercury was every applied on crops, but stranger
things have happened.
**Q.2005 Some people are becoming increasingly worried about the synergistic
effects of chemicals. Are there regulations that pertain to conducting toxicology
tests that involve different cocktails of chemicals with new chemicals that
can be found in different environments (industrial and household)?
A. No. Consumer products are normally tested as the whole product, so the many
chemical present will interact. Here is a link from my toxicology class about
that:
http://www.faculty.uaf.edu/ffrap/ENVE_652/Module09/Submodule9C_Mixtures/9C_Mixtures.htm
**Q. I noticed when reading about the routes of exposure that injection was
not mentioned. Is this route omitted when determining toxicity?
A. For human exposure to environmental chemicals, injection is not an issue.
Since most toxicity is done in laboratory animals, injection is sometime done.
There are many complexities to this testing. Ideally animals are exposed in
the same manner as humans receptors. For example, if the solvent used to make
decaf coffee is under consideration, the animals will be given doses of the
solvent in coffee. When a scientist is trying to understand the exact mechanism
of toxicity, they will often use direct injection or other means. "iv"
means intravenous; "ip" means intraperitoneal; "im" intramuscular
and so on.
**Q. I found the incidents on organic mercury very interesting. Organic lead
is also very toxic, much more than inorganic. But when testing for contamination
at leaded gasoline spills, the state requires a total lead test and not organic
lead. I suppose there are reasons - maybe a 'risk management' issue?
A. I'm not sure. Maybe total lead is cheaper to test for. It is often difficult
to get at the species of metal, valence state, in simple chemical analysis,
because the state changes with oxygenation, pH, and reagent chemicals.
Q. One discussion that stuck out in my mind involved the debate over the accepted
residual levels of organophosphates on potatoes. A group of scientists representing
an outside not-for-profit organization were adamant that the residual levels
for potatoes should be equal to that of tomatoes. They wanted the data for tomatoes
(that had been calculated) to be extrapolated and used for potatoes (which were
not calculated due to funding and time constraints). The argument of the group
was that both tomatoes and potatoes were members of the Nightshade Family, and
thus the data should be interchangeable. Of course later in the discussion it
was pointed out that potatoes are grown underground, and while the vines are
typically burned down with Paraquot at the end of the season, the actual potato
never really sees a pesticide until they it hits the storage warehouses where
they are most commonly treated with fungicides, not insecticides.I am probably
getting ahead of the game with this statement, because I know you stated in
the Introduction and Goals we the students will learn that often times the risk
numbers are not based on hard science. If so, please disregard my suggestion.
A. Here we have to distinguish risk assessment from risk management. Although
you just pointed out how a risk management decision was made not to do a risk
assessment.
Q. Stupid Question: who coined the term; "The solution to pollution is
dilution."?
A. It was a mantra in the 1960's.
C. The Paraclesus quote is interesting in contrast to the definition of homeopathy:
Miranda Castro R.S. Hom., author of The Complete Homeopathic Handbook, 1990:
"The Similum or Law of Similars: This basic law of homeopathy is similia
similibus currentur: 'let likes be cured with like'. Based on this premise,
the first homeopathic principle states that any substance that can make you
ill can also cure you - anything that is capable of producing symptoms of disease
in a healthy person can cure those symptoms in a sick person. By 'symptom' the
homeopath means those changes that are felt by the patient (subjective) or observed
(objective), which may be associated with a particular disease, or state of
dis-ease, and which are the outward expression of that state".
R. In Paracelsus' day, many patients were treated with incantations and elixir
of bat wings. His notion was quite novel and marks the start of scientific toxicology
and pharmacology. Besides being a physician (retired) and pharmacist, he was
also an avid botanist and described many useful and dangerous plants. Homoeopathy
and many other medical related philosophies arose in the late 18th and 19th
century. Orthodox physicians of those days practiced bleeding patients, strong
laxatives, and other horrid practices, including surgery with dirty knives.
It was not hard to have a better success rate with holy water. You might look
up hormesis, a modern concept that small doses of many harmful chemicals are
good for you. Sometimes that is true.
Q. What does divining mean?
A. And you call yourself and environmental engineer. The practice of "dowsing"
is how you invoke the spirits to help you find water. The "divining rod"
is the forked stick (two brass welding rods also work) you use to channel the
spirits.
This mentions the connection with Thor.
http://www.metaphysic.com/freebooks/myths/C2.html
But you can go further with divining rods, see:
GEOMANCER
Geomancy is the study of the location and alignment of prominent landscape features
and sacred sites, and Rodney Carr-Smith, who was featured in our programme,
is a modern day geomancer with a difference. Rodney has returned home after
30 years exploring earth energies and consciousness around the world, living
the last 12 years on a Native American reservation. Rodney practises by dowsing
with a single divining rod to try to rediscover serpent energies (intangible
earth energies) in the landscape, as opposed to looking for an association between
straight ley lines. Although most commonly associated with finding water, dowsing
is widely used for other purposes including geophysical and site surveying,
mineral prospecting, medical diagnosis and healing, archaeological searches,
agriculture and soil testing and tracing lost objects.
http://www.meridian.tv.co.uk/whats_on/programmes/3minutes/factsheets/2001/2001_11.shtml
Q. Good Morning Dr. Perkins. I just finished reading through all of Module
1 and the associated articles. It is good to see that old Paracelsus quote again,
especially in today's society where everyone seems to believe that "natural
herbal remedies" are inherently beneficial with no potential side effects.
As a person with a strong background in plant toxins and regulatory biology,
I have very different opinion on these matters.
A. See what I wrote for my toxicology class on Foods and Fads: http://www.faculty.uaf.edu/ffrap/ENVE_652/Module14/Foods_and_Fads/FandF.htm
Q. I believe that this is a very important statement to drive home to everyone,
because it has been my experience that science and politics are definitely not
mutually exclusive in American society.
A. While not mutually exclusive, they have very different purposes. Read the
beginning of this: http://www.faculty.uaf.edu/ffrap/ENVE_652/Module12/12A_RegulatoryTox/12A_RegulatoryTox.htm