DogMa > wrote:
>Good news is that DDT and many other controlled pesticides aren't
>actually particularly bad for people in applied amounts. (I'm not sure
>that there is even a single example of someone dying from ingesting
>grams of the stuff, which happened not infrequently.) DDT was banned
>because - being fat-soluble and metabolized only very slowly - it
>concentrates up the food chain. So top-predator birds had problems with
>egg shell development. We'd have to eat the cats that fed on the mice
>that ate the beetles that ate the Pu-erh weevils...

Precisely. I grew up with sprinking DDT between the sheets before
getting into bed, and pouring DDT-laced diesel into the fire before
cooking outside to keep the bugs away. Not that it isn't an environmental
disaster, but it's not a human health disaster. Also, sad to say, it's
not as effective as it was when I was a kid because insects have evolved to
develop tolerances. Bug generations are very short.

That said, if you want to do testing for DDT, there is an easy titration
test that has a high false positive rate, a harder titration test that
has a lower false positive rate, and a chromatographic test that requires
much less material and is much easier if you have the machine. I assume
any professional laboratory today is using the chromatographic method,
but if you want to do it at home you can get the reagents to do the older
tests.

>I'm not a medic or biologist, but my impression is that many of the
>really nasty pesticides like cholinesterase inhibitors have high acute
>toxicity (e.g. to field workers) but very little chronic risk in lower
>doses. Kind of the opposite of heavy-metal poisoning, like recent lead
>problems. FWIW, I don't worry about it, and I do think a lot about food
>safety.

Yes, but don't forget there are some organometallic pesticides in common
use today now, which are indeed the opposite. On the gripping hand, we
also have to contend with the fact that the pesticides used in the field
are not exactly reagent-grade and come with all kinds of other contaminants
in possibly significant amounts.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."