| llladd@sprintmail.com 2006-03-22, 1:31 pm |
| Dear Ms. Crane,
Here is a copy of a letter I sent to Ms. Gallegos, a reporter in Iowa
City, to pass on to her contacts in Hills, Iowa where some households
drink up to 18 ppb perchlorate in their private wells.
Larry Ladd
http://www.perchlorate.org
Dear Citizens of Hills, Iowa:
The issue of perchlorate in the environment started in my hometown of
Rancho Cordova, California, back in 1996. Since then estimates of the
safe level of perchlorate consumption have ranged from 400 ppb to 1
ppb, so our neighborhood has independently monitored how people became
ill when drinking 200-300 ppb perchlorate (and at least one other
chemical, a potent carcinogen called nitrosodimethylamine) and used
that information to judge for ourselves what kind of illness might be
indicative of a perchlorate overdose. I visited with you three years
ago to share this information, and wanted to give you an update.
The 18 ppb standard used at Hills is a bit on the high side of the
current range of debate between the 2 ppb Massachusetts standard and
the 25 ppb standard issued by the White House. Because toxicology is
generally an exponential process, the midpoint between 2 ppb and 25 ppb
is roughly the California public health goal of 6 ppb rather than
mathematical average of 13.5 ppb. So let me tell you what might go
wrong if Massachusetts is right and there is good reason to have a
tough perchlorate standard of 2 ppb.
Perchlorate at high doses can cause a multitude of problems, but the
chemical is urinated out so efficiently (half life of 8 hours in the
bloodstream of rats) that it doesn't accumulate. All bets are off
though if someone cannot urinate perchlorate very well, and this may be
true of folks with slightly acidic blood (e.g. diabetics having ketone
problems) or low bicarbonate in the blood (e.g. infants with diarrhea).
Hyperthyroid persons who took perchlorate medicinally in the late
1950s-early 1960s used to suffer from skin rashes and stomach aches,
and we now have a pretty good scientific idea of why that happened.
Perchlorate does accumulate in skin cells as they rise from the dermis
to the epidermal surface and dry out -- the half life of perchlorate in
rat skin is 32 hours, 4 times longer than its persistence in the blood
stream. Perchlorate also absorbs far ultraviolet light and becomes much
more reactive in this high energy state, so it's plausible but not
proven that perchlorate in the skin could aggrevate what would already
be a pretty bad sunburn. At the high doses given medicinally
perchlorate would open calcium channels and induce skin contact
sensitiviy, but ultraviolet activation may also be part of the rash
problem.
As for the stomach, the same transporter protein that imports iodide
into the thyroid also imports thiocyanate into the stomach acid.
Thiocyanate is the substrate of choice for elements of the innate
immune system called lactoperoxidase and myeloperoxidase. These
peroxidases are released by white blood cells and act like self-guided
machine guns, producing a stream of oxidizing particles that attack an
invading pathogen. Thiocyanate is the ammunition of choice for these
molecules -- enough killing power to wipe out most pathogens, but not
so reactive as to produce very many collateral casualties. If
thiocyanate is in short supply, though, the peroxidase uses ubiquitous
chloride to produce hypochlorite, or household bleach. Too much bleach
in you produces what the scientists call oxidative stress, which in the
long run is not a good thing. Another part of the innate immune system
in the throat, lungs, and stomach called defensin may also be adversely
affected by too much perchlorate, but that idea has yet to be tested.
If the immune system in your stomach is not working well then a
bacteria called Helicobacter pylori can successfully colonize the
stomach to the point where the infection produces ulcers, gastric
adenocarcinoma, and gastric lymphoma. We are looking at a high
incidence of gastric lymphoma around a rocket manufacturing complex at
the Van Nuys, California airport to see if it reflects occupational
exposure to perchlorate. Probably the most perchlorate-rich diet in the
world is in Chile, where their natural fertilizer deposits contain a
high amount of perchlorate. The farming area of Chile also has some of
the highest stomach cancer rates in the world -- stomach cancer is the
number one cancer killer in Chile. This is probably due to a multitude
of factors: two strains of pylori bacteria co-existing in the region, a
high smoking rate, bountiful consumption of preseved fish in the diet.
But perchlorate is part of the environmental mix there and is a logical
suspect as a cofactor.
Another global immunosuppression mystery is Kaschin-Beck disease in the
arid, northern parts of China and Tibet. Something in the water there
suppresses the immune system allowing a fungus endemic in local grains
to successfully attack the bones and joints. Given the recent data on
spontaneous generation of perchlorate in the atmosphere from
ultraviolet light and lightning, and its accumulation in arid
environments, perchlorate-compromised immune systems have to be ruled
out in inner Asia as well.
When I visited Hills no one had any stories of widespread rashs,
stomach problems, or crippling fungal infections. But just to be on the
safe side, if you would pass this on to your friends and neighbors, I
would appreciate it.
Sincerely,
Larry Ladd
http://www.perchlorate.org
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