The LD50 is at best a crude measure of toxicity. There is also the problem of large individual differences in toxicity between individuals. Phthalate esters cause me a lot of problems but many individuals are not as sensitive as I am. In some individuals the P450 liver system can handle phthalates apparently and clear them from the body. in other individuals the phthalates are not cleared and bio accumulate to very toxic levels. Where should the levels be set. It is also interesting to look at the UN report on toxic exposure levels across various countries. The vary quite a bit.
At 10:04 PM 8/24/99 EDT, you wrote:
>Thanks Brian D. Williams for your analysis. Mine is similar, not that I am
>'afraid of roundup', or against genetic engineering. Your point is well
>taken, these seem to benefit big agribiz most, and consumers secondarily.
> While I thank Robert J. Bradbury for looking up the LD50 of Roundup, this
>misses my point. It is not necessarily just the roundup, but the
>opportunity to build in plant resistance to all of these chemicals, but
>ignoring the human resistance to the chemicals. Just because so many mg/kg
>kills half the rats, does not mean that lower doses are safe for humans. The
>EPA is finding with many biocides, that for example children are much more
>succeptable to harmful effects, or that low doses do not kill by direct
>toxicicty, but some compounds act as hormones at very low levels causing
>endocrine disruption. A simplistic LD50 analysis ignores interactions among
>dozens of chemical adulterants in our diet. Often as with agent orange, it
>is not the main compound which is ultra bad, but by products from the organic
>synthesis (dioxins) in minute quantities that are worse than the main
>product. The issue is complex I agree, and I have a BS in chemistry, so I am
>no chemophobe. But in the interest of life extension, less chemicals in the
>diet that my species has not had time to evolve with is better, at least this
>is a cautious approach.
> So, yes, we should support accurate labling, so consumers have free choice,
>we should have more biotech research on humans to reisist cancer and other
>chemical degredation. Monsanto and its share holders are second to the
>health of the population [and me].
Ralph Lewis, Professor of Management and Human Resources College of Business
California State University, Long Beach
Long Beach, California