Beata Lisek:
Thank you for your informative reply.
>>That probably was my statement indeed, so I will give you a reference:
>http://www.uni-tuebingen.de/KRAUSS/amalgam.html
This is quite an interesting article and deserves thourough evaluation.
>In the report mentioned above, the mean (averaged over 17,351
>subjects!) 'exposure' via oral ingestion was below 21 ug/day for only
>30 % of the subjects.
The authors of the afore mentioned report do a fair job of estimating
exposure to mercury from almalgam (without considering the bioavailability
of amalgam mercury). These authors indicate the following:
"About 30% of the subjects lie, according to this method of extrapolation,
within the assumed range of the WHO for the uptake of total mercury of up to
21 µg. For a further 40%, burdens that are still below the PTWI values of
the WHO (300 µg total mercury per week) are found. About 30% of the subjects
take up more mercury per week than the PTWI value. 3.5% of the subjects are
more than 3 times higher than the PTWI value and 1.9% are 4 times higher."
The authors then go on to provide the following information of the
bioavailability of mercury forms (the article provides more discussion on
this and the previous issue):
"The fact that mercury is taken up in its various binding forms does not, of
course, mean that it is subsequently absorbed by the body. Hgo vapour in the
lungs is absorbed to about 80%, whereas Hg2+ in the intestines is taken up
to only about 7 - 10%. Methylated mercury is absorbed from the intestines to
about 80%, but amalgam particles and mercury droplets are virtually not
absorbed at all."
>>And as the amount that corresponds to 0.3 ug/m^3 equals 0.3 ug/m^3 *
>20 m^3/day = 6 ug/day and 21 ug/day > 6 ug/day, I think my statement
>still holds. (I'm not yet talking about absorption here.)
Your statement holds only if you are talking about inhalation exposure
alone. In fact, the article you reference indicates that the test
population is assumed to derive less than 2 ug from the total exposure
through inhalation (amalgam and other indoor and out door mercury sources to
air). 2 ug is less than 6 ug. Other sources mentioned in the article your
reference paint a more detailed picture of mercury exposure from other
sources (diet, water, and air), compare that with their findings, and then
compare that with applicable international standards for acceptable total
mercury exposure (up to 300 ug per week).
>Further, I don't know yet whether I can agree with this figure 0.01 %
>absorption. Is this a general figure, applicable to all ways to ingest
>all forms of mercury?
>In what form was the mercury ingested? Was it in the exremely small
>particle size (high area-to-volume ratio => high absorption rate, high
>methylation rate by bacteriae in the oral cavity as well as in the
>gut) as in when the mercury is 'dissolved' in the saliva? Or was it
>one big 'blob' of mercury? Please help me to get a grip on this
>intriguing question.
The article you mention has a brief description of the relative
bioavailability of different mercury forms via inhalation and ingestion.
The 0.01 percent number I quote comes from the US Mercury Study Report to
Congress <http://www.epa.gov/oar/mercury.html>. You should down load Volume
V., Health Effects of Mercury and Mercury Compounds, and go to page 2-1
within the first paragraph of section "2.1.1.2 Oral." The statement is
similar to the one I made previously. The US EPA supports the statement
with a reference to Bornmann et al. 1970.
>To me it looks extremely low (well, to be honest: it *is* extremely
>low), even too low to be accepted by me without viewing the report and
>evaluating the research methodology and the measurement setup that
>lead to this figure. Would you please be so kind to (let someone) send
>me a copy of this report? For this please leave your e-mail address in
>order that I can contact you to arrange this.
My e-mail address should appear at the end of this reply. The reference you
request can be obtained from the US EPA web page provided above. The down
load does take some time - please be patient.
>>I hope that you will respond similarly, by sharing your knowledge in this
area.
>>I look forward to a meaningful discussion of this issue.
Your information and kind response are most welcome. Please continue to
offer additional information. Your reference is very much appreciated and
provides valuable insight into mercury exposure from amalgam fillings. I
will take great care to more fully evaluate this source of information.
Kind regards.
James S. Smith, Jr., Ph.,D.
President & Toxicologist
OAK CREEK, Inc.
RR 3 Box 246B
Route 22
Gorham, Maine 04038-9428
Voice: (207) 929-6375
Fax: (207) 929-6374
E-mail: jssmith at oak-creek.net
WWW: http://www.oak-creek.net/
