"Martin" wrote in message
...
On 03/06/10 01:32, Ian B wrote:
Jeff Layman wrote:
(snip)

http://www.dgsgardening.btinternet.c...l.htm#sodchlor

There is very little information at that ref.

Did you read it? It is highly toxic to humans and animals breaking down
red blood cells, sterilises the ground and persists 6 months to five
years in the ground. Do your really want that getting into your water
supply?

Did I read what, my Norwegian friend? What you have quoted is more or less
what it says at that ref in its entirety. It is a nonsensical summary.

Ever heard of haemolysis? Water breaks down red blood cells if its
"concentration" is too high (ie the concentration of salts is too low).
Anyway, the effect of chlorate on erythrocyte membranes has been known for
at least 25 years, so why the sudden ban? You might like to read this -
part of a report to the Californian environmental authorities
(http://oehha.ca.gov/water/pals/chlorate.html):

"Human Toxicity Studies

Lubbers and Bianchine (1984) studied the short-term effect of administration
of chlorine dioxide and its metabolites, including chlorate, on human
volunteers. Ten male subjects were administered 1,000 mL of water containing
varying concentrations of sodium chlorate (range 0.01 - 2.4 ppm chlorate).
The control group received deionized water. Treatments were divided into two
500 mL aliquots; administered four hours apart. The study involved a series
of six treatments in 16 days, which was considered as a single
time-dependent experiment. Blood and urine samples were collected from all
study participants. No adverse physiological effects were identified,
although there was some variation between the treatment group and the
control group with regard to bilirubin and serum iron measurements. In a
companion study, normal adult male subjects were administered 500 ml of a 5
ppm solution of chlorine dioxide, chlorite, or chlorate daily for 12 weeks
(Lubbers et al., 1984a), corresponding to a dose of about 0.04 mg/kg.
Physical examinations, collection of blood and urine samples for laboratory
assays, and taste evaluations were conducted on a weekly basis during the
treatment period and for eight weeks following cessation of the treatment.
Any value for an individual subject that differed from the group mean by
more than two standard deviations was noted. The authors reported that "no
clinically important physiological effects" were observed. A small number of
subjects yielded abnormal hemoglobin electrophoresis patterns, but these
results were randomly distributed among the groups. In a third study, a
small number of subjects with glucose-6-phosphate dehydrogenase deficiencies
which might make them more susceptible to oxidative stress caused by the
chlorine disinfectants was exposed to the same dose of chlorite daily for 12
weeks (Lubbers et al., 1982, 1984b). Some statistically significant trends
in biochemical or physiological parameters (albumin/globulin ratio, thyroid
hormone levels, mean corpuscular hemoglobin, and methemoglobin values) were
observed, but were judged to be of no clinical significance. Chlorite and
chlorate can be expected to have similar biochemical effects, but do not
appear to be absorbed and distributed in the same fashion and are not
interconvertible in vivo, according to the data from rat studies
(Abdel-Rahman et al., 1979b, 1984a)."

And what did the Californian authorities conclude from this? (Remember they
are some of the most environmentally "keen" authorities anywhere!) They
haven't banned chlorate:

"OEHHA recommends an action level of 200 ug/L (ppb) chlorate based on the
male rat data (rounded). We believe this level would be adequate to protect
against any potential toxic effects in humans. This conclusion is supported
by the human studies of Lubbers and coworkers, who found no effects in adult
male humans with subchronic chlorate doses of 2.5 mg/day. This dose would
correspond to a drinking water concentration of 1.25 ppm with a drinking
water consumption of 2 L/day. The recommended action level is about
one/sixth this no-observed-effect level."

And as to your comment about the water supply, perhaps you can explain to me
how a powerful oxidising agent remains stable in groundwater long enough to
reach the water supply when there are so many reducing agents around which
will inactivate it?

--

Jeff