Karl:

Karl Heinz Zuber wrote:

> 1. the old "dosis venenum facit" (The dose makes the poison) is not
> ALLWAYS true. There is, as far as i remember, one mechanism where there
> are no safe limits: If genes are affected, the repair mechanisms as well
> as the damaging mechanisms are stochastic. That means that even one
> molecule of the substance can cause damage, and the safe level is 0.
> Probability of effect is of course lower with lower doses.
> MERIAN ("Metals and their compounds in the environment", VCH, 1991)
> (this one is in english ;-) mentions some evidence for genotoxic effects
> of lead and several compounds.

"dosis venenum facit"      It always sounds better in French doesn't it?

I am not clear on your point.
stochastic - adj. 1. Of, relating to, or characterized by conjecture; conjectural.
How does that lead to the notion that, with respect to genes, "...even one molecule of the substance can cause damage, and the safe level is 0." ?  Genetic material - DNA - is being damaged all the time, mainly from natural, internal sources. The largest source of damage to DNA is oxygen radicals, a product of metabolism. I have not yet concluded my research on whether oxygen is essential to life, but I will report back when I finish. I may do my own research on this, so if you don't hear back
from me assume the experiment didn't go well.

Radiation (from natural as well as man-made sources) is also another source of DNA damage. So is exposure to "chemicals", but that is miniscule compared to the endogenous damage. Oxidation and the damage it does to DNA is believed to be the single largest contributor to what we call aging and the diseases of aging, such as cancer. That is why everybody is hyping "antioxidants", wanting people to believe they can forestall the effects of aging by consuming things that contain antioxidants.
However, the body constantly repairs the damage to DNA. Bottomline is that lots and lots of things, mostly natural and mostly internal, cause DNA damage and the body is constantly repairing it, so the idea that any dosage above zero irreversibly damaging the genes is just not valid (otherwise many of the natural foods we eat would be off limits, as would breathing).
>
>
> 3. One more from MERIAN: The increase of lead in sediments during the
> last 150 yrs was up to 20-fold, 4-fold in south pole snow. Of course
> that is due to atmospheric pollution, gasoline etc. and not to
> electronics, but it means that anthropogenic lead is not in principle
> negligible, as you implied.

The debate and my argument is not about anthropogenic sources of lead. It is about lead in solder in electronics in landfills (numbnuts habitually chewing on electrical wiring notwithstanding).  I have never addressed the issue of whether the total costs and burdens of removing lead from gasoline were outweighed by the total benefits and savings to human and animal health. That has not been the issue. We have been addressing the issue of whether the total costs and burdens of removing lead from
solder in electronics are outweighed by the total benefits and savings to human and animal health.

Also, I have seen no answers to my questions about lead in solder in landfills being more likely to leach than lead in lead sulphide or in such other forms that may exist in nature. Is it true that lead once touched by man becomes more water soluble and more mobile than lead never touched by man?  If so, why?

BTW I know it's Latin, just seeing who's paying attention. :>)

Best regards

Chuck Dolci

-------------------------------------------------------------------------------Leadfee Mail List provided as a service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Leadfree
To temporarily stop delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL
Search previous postings at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-------------------------------------------------------------------------------