> > Penicillins were a very fortunate find. Most antibiotics (and many
> > drugs) have a higher mammalian toxicity, yet are still used
> > because the benefits often outweigh the costs.
> ALL of them depend on differences that exist between human and a
> metabolism. In any case, the principle is the same: Less toxicity to
> human tissues and organism, more specificity directed toward disease
> or pest.
I guess I don't understand what we are disagreeing about here. My point
was just that the type of cost/benefit calculation made for antibiotics
is exactly the same as for pesticides. In fact, antibiotics are really
a class of pesticide.
> > This was true only of the very earliest pesticides such as lead
> > arsenate. Even the much vilified DDT is vastly more toxic to
> insects than
> > to mammals. If it wasn't so resistant to microbial attack it would
> be very
> > safe.
> "Vastly more toxic to insects than to mammals"? It's carcinogenic to
I wasn't familiar with the literature on this subject, so I did a quick
search and turned up 96 relevant abstracts. Most of the studies on
environmental exposure concluded that there was no association between
DDT/DDE exposure and cancer incidence. Some studies on much higher
occupational exposures showed a weak association. I'll send you the
abstracts if you want.
> "If it wasn't so resistant to microbial attack it would be very safe".
> I sometimes wonder what world you live in. You can be unreal on
Douglas, everyone knows that food-chain accumulation is the big problem
with DDT and many organochlorine compounds. Without this, the weak
toxicity would be irrelevant. If you dispute that, we can trot out and
examine the data. That would be more productive than personal attack.
> > The trend in pesticide development for the last decade or two has
> > toward highly selective chemicals that are significantly
> > less toxic than table salt to humans.
> The substances you call "significantly" less toxic do a lot of harm
> and far
> safer alternatives are available, that work on the basis of different
> principle, at bottom.
I do some work with seed-treatment fungicides. Many of these are used
at very low rates, and have very low toxicity to boot. They are
extremely selective. Anyway you slice it, the environmental cost is
low, and the efficacy is high. Why don't you explain how these "do a
lot of harm." A similar case can be made for some other uses of
pesticides. You just can't generalize across all pesticides and uses
and assume that the environmental cost is significant. Every case
should stand or fall on it's own merits.
> > I have been working on biological control (mostly in the seed and
> > disease context) for most of my professional life. I have plots in
> > field right now. Without exception these have been far less
> > than chemical controls.
> I'm really sorry you haven´t been able to make biological control
> work for
> you. Perhaps the environment you´re in is already gravely unbalanced
> or you
> are in the wrong line of work. Have you considered becoming employed
> by a
> manufacturer of toxic agrochemicals?
You can't generalize about biocontrol either. The fact that some
biocontrol strategies work, doesn't mean that biological controls are
universally useful. The little secret about biocontrol research, at
least in the public sector, is that there has been a fair amount of
money available to do this kind of work. Everyone I knew when I was at
the University was working on biocontrol, at least in bootleg mode, to
try to get data to write a proposal to hook into that money (me too).
There was great incentive to get positive results. I just think that
the material I was dealing with (sweet corn seedling diseases) wasn't
very amenable to biological control. I tried a lot of different things,
but fungicides were always way better.
> > You are overstating the danger. If pesticides are so dangerous, how
> > tests on various mammals are negative or immeasurably slight? If
> you think
> > the toxicological consensus regarding risk estimation is wrong,
> > explain why.
> Dale, you're placing the burden of proof on the consumer.
You're changing the subject. The burden of proof is clearly on the
manufacturer because they pay for the testing. You are claiming that
the toxicological methods endorsed by the scientific community are
ineffective. Description of your toxicological rationale for this claim
would be more productive than your continued polemic.
> This ignores those who DON¨T hold up well enough (i.e. children, the
> old and ill, more sensitive individuals etc.), and presupposes a
> "natural" decline that is in reality the result of a steady
> deterioration of the human organism due to continued contact with the
> products you seem to like so much, that eventually kill EVERYBODY off
> - but that´s OK because is fits the statistical norm. In short, your
> frame of reference is too limited.
Again, if you have a gripe with how they do the toxicology, let's hear
the specifics. I have attached below the abstract of a paper that
summarizes my take on the toxicology. The devil is in the statistical
details. I am willing to go into that with you.
> Sometimes, I kind of wonder why someone with your perspective (or lack
> vision) is on this list.
I can see that you have a strong political instinct. I look at these
issues from a practical, hands-on perspective. IMO, sustainable
agriculture is too important to leave it exclusively to armchair
agronomists, utopian extremists and detached administrators.
> > We should continue to improve methods of risk estimation. But in
> the final
> > analysis, decisions about pesticide registration will still to be
> made in
> > the light of the risk-benefit calculation, and IMO, this is
> This is true, but that requires clearly defined goals that are
> difficult to
> promulgate when so many lack knowledge of what's possible. Things are
> not all
> that relative. That´s not how things came to be. Somebody's got to
> go ahead
> and do it, and my responses to this tack will be limited by that fact.
You lost me here. Could you restate this?
> We´re not all on salary or subject to policies someone else made.
If I understand you correctly, I AM offended by this. I am seriously,
and, with some cost to my job and family, attempting to dialogue with
environmentalists. I'll bet I was doing volunteer recycling work before
an environmental thought ever crossed your mind. I have cared about the
earth, and people, as long as I can remember, and that is why I became
an agronomist. Do you think I am doing this because Pioneer wants me
to? I'd probably get reprimanded for engaging in such public debate if
they parsed the email. (But I do enjoy vigorous debate, especially when
I am right ;-)
> Record 82 of 96 - BA on CD 7/97-12/97
> TI: The causes and prevention of cancer: Gaining perspective.
> AU: Ames-B-N; Gold-L-S
> SO: Environmental Health Perspectives 105(SUPPL. 4): 865-873
> PY: 1997
> LA: English
> AB: Epidemiological studies have identified several factors that are
> likely to have a major effect on reducing rates of cancer: reduction
> of smoking, increased consumption of fruits and vegetables, and
> control, of infections. Other factors include avoidance of intense sun
> exposure, increased physical activity, and reduced consumption of
> alcohol and possibly red meat. Risks of many types of cancer can
> already be reduced, and the potential for further reductions is great.
> In the United States, cancer death rates for all cancers combined are
> decreasing, if lung cancer (90% of which is due to smoking), is
> excluded from the analysis. We review the research on causes of cancer
> and show why much cancer is preventable. The idea that traces of
> synthetic chemicals, such as DDT, are major contributors to human
> cancer is not supported by the evidence, yet public concern and
> resource allocation for reduction of chemical pollution are very high,
> in part because standard risk assessment uses linear extrapolation
> from limited data in high-dose animal cancer tests. These tests are
> done at the maximum tolerated dose (MTD) and are typically
> misinterpreted to mean that low doses of synthetic chemicals and
> industrial pollutants are relevant to human cancer. About half the
> chemicals tested, whether synthetic or natural, are carcinogenic to
> rodents at such high doses. Almost all chemicals in the human diet are
> natural. For example, 99.99% of the pesticides we eat are naturally
> present in plants to ward off insects and other predators. Half of the
> natural pesticides that have been tested at the MTD are rodent
> carcinogens. Cooking food produces large numbers of natural dietary
> chemicals. Roasted coffee, for example, contains more than 1000
> chemicals: of 27 tested, 19 are rodent carcinogens. Increasing
> evidence supports the idea that the high frequency of positive results
> in rodent bioassays is due to testing at the MTD, which frequently can
> cause chronic cell killing and consequent cell replacement-a risk
> factor for cancer that can be limited to high doses. Because default
> risk assessments use linear extrapolation, which ignores effects of
> the high dose itself, low-dose risks are often exaggerated.
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