OT Mercury discussion:
Bernie Bennett,
when commenting on George Anderson's rant about camera
batteries not contributing significantly to mercury pollution, referenced an
interesting news story on how mercury appears to be transported along the
nerves to the brain rather than via the blood brain barrier (
http://www.wired.com/news/news/technology/story/21674.html
Headlined "Mercury's Scary Migration". ) Normally metals like Aluminum or
Mercury do not cross the blood brain barrier easily leading to relatively
lower levels in the brain. This is partly why we do not get demented from
aluminum pots and aluminum in the water (municipal process sometimes adds
Aluminum) Except where levels get very high eg. Old days of renal dialysis
where the relatively poor absorbtion through the stomach is bypassed and
blood levels get high.
George may be right about mercury batteries not being a very major
problem, however there is no doubt that mercury is very much more serious
toxin than common heavy metals such as lead. This is because it vapourises
easily and can be inhaled and it is also absorbed through the skin more
readily. I know an endodontist who got the "mad hatter disease" from doing
root canals for twenty years and eventually drowned during a resulting
siezure. The substantially shorter life expectancy of science teachers in the
past, was speculated to be the result of mercury vapour fumes from small
quantities of spilled mercury in between the floor boards of science labs.
Nowdays dentists are very careful not to handle the mercury directly before
it has formed an amalgam and are very careful to use suction and water to
minimise mercury vapour production from tools heating old fillings during
drilling.
It is always interesting how even seemingly small quantities eventually
add up. A friend worked for a disk drive manufacturer and they wanted to use
a minute quantity of radio-active Polonium to discharge static from the disc
drive platters.(like the old record anti-static devices). It turned out that
they would have consumed more than the worlds total production per annum and
the only commercial vendor would have had to build a completely new facility
as the quantities manufactured would exceed some magic threshold of
radioactive material. Needless to say they did not use it.
Denton commented on the advantage of protecting the factory workers
who have to produce toxic products. I did some consulting work with a large
domestic battery manufacturer a few years ago and it was interesting the
lengths they go to to meet OSHA standards and to prevent worker litigation.
The lead battery factory had mandatory annual lead level checks and water was
used everywhere to keep dust levels down. Some workers in higher risk areas
got more frequent checks and more protection.The NiCd division evidently used
full body suits and forced air respirators for the workers dealing with the
Cadmium. There was a landmark US sex discrimination suit with Johnson
Controls over giving the most hazardous (high pay) jobs only to men in one of
their lead acid battery factories. The female workers argued that they were
helping the men by forcing improvements in work conditions since the factory
would not dare to have such hazardous conditions for women who might bear
children. The introduction of NiMh batteries which are relatively less toxic
than Cadmium is a great improvement. And Lithium batteries should help
everybody calm down! Interestingly, until Mercury got banned in regular
Alkaline batteries they were a major user of mercury despite the trace
amounts used, again just because of the huge volumes.
Tim Hughes
Hi100@xxxxxxx
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