A Step in the Wrong Direction on Arsenic A Step in the Wrong Direction on Arsenic A Step in the Wrong Direction on Arsenic

William_Noyes notarealaddress at fictional.org
Thu Nov 18 22:50:57 EST 2004


ACSH isn't a source I'd trust whatever the merits
of their specific position on this topic.


"aubrey stimola" <stimola at acsh.org> wrote in message
news:a08e60ce.0410191059.6e44bd0f at posting.google.com...
> A Step in the Wrong Direction on Arsenic
> www.acsh.org/factsfears/newsID.459/news_detail.asp
>
> According to a study in the August 2004 issue of Chemical Research in
> Toxicology, arsenic could be toxic at much lower levels than
> previously thought, raising the alarm that the new EPA drinking water
> standard of 10 parts per billion (ppb), to take effect in 2006, might
> still be too high.(1) But don't dump the glass of tap water yet; the
> conclusions of this newest study were based on an in vitro study of a
> rat cell line.
>
>
> While animal experiments play a crucial role in many fields of
> research, there has been much scientific debate about how heavily we
> can rely on high-dose, single-species animal tests as indicators of
> human toxins and carcinogens. Over-reliance on such studies as the
> basis for increasingly stringent regulations of various chemicals
> lacks scientific credibility and often results in unnecessary health
> scares. The scares draw energy and financial resources away from
> actual health dangers. The current study, conducted by researchers at
> Dartmouth Medical School, takes the issue of relying on animal tests
> another step in the wrong direction.
>
>
> The term in vitro -- literally, "in glass" -- refers to any biological
> process that takes place in an artificial environment such as a Petri
> dish or a test tube. An essential part of medical research, in vitro
> procedures are most useful in the early or intermediate stages of
> experimentation to study the effects of a substance in isolation,
> without interference from natural bio-mechanisms involving hormones,
> enzymes, and immune responses. They have been used to understand
> mechanisms of toxicity, to identify cellular target sites of action,
> and to characterize cellular and molecular changes prompted by
> exposure to toxicants. They reduce variability, allow for greater
> control of the experimental environment, and are quicker and cheaper
> than their in vivo -- "in life" -- counterparts.
>
>
> However, extrapolating in vitro results to whole animal situations --
> even animals of the same species that provided the cell cultures --
> has many limitations. These studies cannot take into account toxicant
> distribution in a whole organism, route of administration, or
> metabolism of the substance. Further, cells in culture are not
> exposed to circulatory, nervous, or endocrine system functions, or to
> the millions of cells, thousands of enzymes, hundreds of chemical
> messengers, and dozens of organs that work in concert within a whole
> organism. In other words, the biochemical processes leading from
> toxicant exposure to toxic effect in vivo are too complicated to be
> duplicated in vitro. This is very much the case when it comes to
> cancer forma......
>
> Please visit http://www.acsh.org/factsfears/newsID.459/news_detail.asp
> for the conclusion of this article by Aubrey Stimola www.acsh.org and
> www.healthfactsandfears.com
>





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