Pyrethrum flowers and pyrethroid insecticides.

Pyrethrum flowers and pyrethroid insecticides.

The natural pyrethrins from the daisy-like flower, Tanacetum or Chrysanthemum cinerariifolium, are nonpersistent insecticides of low toxicity to mammals. Synthetic analogs or pyrethroids, evolved from the natural compounds by successive isosteric modifications, are more potent and stable and are the newest important class of crop protection chemicals. They retain many of the favorable propertie...

Sensitization risk of pyrethroid insecticides.

Pyrethroid Insecticides: Use, Environmental Fate, and Ecotoxicology

There was little public concern over potential nontarget effects of pesticides until the 1962 publication of Rachel Carson’s Silent Spring (Delaplane, 2000; Moore et al., 2009). Organochlorine insecticides (such as DDT) had been used intensively and were credited for many of the problems highlighted by Carson. Because of their accumulation in the environment and reproductive toxicity in people,...

Synthetic pyrethroid insecticides: a dermatological evaluation.

Synthetic pyrethroids are lipophilic insecticides whose biological activity seems to be directly related to their chemical structure. In this investigation differences in cutaneous sensation were detected by human participants between synthetic pyrethroids with a cyano group in the (S)-configuration of the 3-phenoxybenzyl alcohol of their molecular structure (fenvalerate) and those that do not ...

Pyrethrin exraction from pyrethrum flowers using carbon dioxide

Extractions of pyrethrins from ground pyrethrum flowers, using supercritical carbon dioxide as the solvent, were carried out in a semi-batch pilot plant (extraction volume: 200 ml). Extracts were very similar to those obtained by hexane Soxhlet extraction, except that the ratio of pyrethrins I to pyrethrins II was lower (1.58 instead of 1.79), and less pigments were present. At 40 8C, the amoun...