Herbicides and PCB’s

Herbicides Largest sales of any pesticide in US - $4bill/yr Most useful are selective ones –Phenoxy herbicides kill broadleaf plants 2,4-D kills broadleaf weeds but not grains and grasses 2,4,5-T kills broadleaf brush – now banned since middle 80’s in US –Because there are trace amounts of dioxin in it –Agent orange is 2,4-D plus 2,4,5-T plus dioxin Di or Tri chloro phenoxylacetic acid

Herbicides Most important other herbicide is glyphosphate (Roundup) –Not a selective herbicide

PCDD’s General family of chlorinated compounds that includes dioxin or 2,3,7,8-TCDD Very stable in the environment Toxic to animals in low concentrations, but may not be toxic to humans at all. Found all over the world in low concentrations

PCB’s Also chlorinated organic compounds that are very stable. Spread out everywhere –Even found in polar regions and in bottom of the ocean Under heat, produce dioxin and PCDF’s (polychlorinated furans) –PCDF’s are more toxic to animals and we think humans

PCB’s in a Great Lakes area

TEQ = Toxicity equivalency

Chloracne from organochlorine compounds

Environmental Estrogens Estrogen-like compounds in the environment –Many man-made but some natural DDT, PCB’s and dioxins Phytoestrogens in soy, wheat, apples, cherries, etc. –May protect against some kind of cancers –Interfere with the normal work of estrogen –May only be a problem at high concentrations

Tiny Concentrations Just because we can detect them, doesn’t mean that they are harmful Overall, humans are living longer, more productive lives We just like to scare ourselves.

H24 – C , 37, 38, 41, 44, 46, 74, 76, 89,