SYNTHETIC PESTICIDES (ECOTOXICOLOGY)

Table of contents :

  • virucides
  • bactericides
  • nematicides
  • algaecides
  • fungicides
  • herbicides
  • herbicide safeners 
  • plant activators
  • growth regulators
  • molluscicides
  • insect attractants
  • insect repellants
    		•
  • insecticides
  • piscicides
  • avicides
  • bird repellents
  • mammal repellents
  • rodenticides
  • mating disrupters 
  • synergists
  • antifeedants
  • chemosterilants
  • miscellaneous
    		•

     
  • pesticides (including polychlorinated organic compounds (PCOCs)) : a poison used to destroy pests of any sort. > 10,000 different pesticides exist, only 600-800 of which are used, for a total of 12,000 commercialized combinations. Nowadays they need very long sperimentation before introduction to the market and it has became very expensive for firms to patent new pesticides => very old products are used. Acute toxicity has the same target organs (CNS, liver, kidney and eventually skin and mucosae) as for many other chemicals, but is far higher as they were designed to be poisons. Most laboratory tests are not available as kit manufacture is poorly remunerative (tests are not so common). Nowadays accidents are quite rare and the actual exposed subjects are manufacturers and consumers eating foods contaminated by trace amounts of pesticides.
    • Carcinogenicity according to 1997 IARC classification : => lymphomas, leukemias, myeloma, soft tissue sarcomas, prostate, CNS and stomach cancers.
    Theratogenicity : thiophthalimides, captan, captofol and folpet may cause cardiac, skeletal, ocular malformations, micromelia, and hydrocephalus
    Numerous anthropogenic chemicals of environmental concern--including some phenoxy acid herbicides, organophosphorus insecticides, polychlorinated biphenyls, phthalates, freon substitutes and some DDT derivatives--are chiral. Their potential biological effects, such as toxicity, mutagenicity, carcinogenicity, and endocrine disrupter activity, are generally enantiomer-selective, and different enantiomers are preferentially degraded (transformed) by micro-organisms in various environments. Environmental changes in soils can alter these preferences, and to suggest that the preferences shift owing to different groups of related microbial genotypes being activated by different environmental changes. In Brazilian soils, almost all pasture samples preferentially transformed the non-herbicidal enantiomer of dichlorprop ((RS)-2-(2,4-dichlorophenoxy)propionic acid), while most forest samples either transformed the herbicidal enantiomer more readily or as rapidly as the non-herbicidal enantiomer. Organic nutrient enrichments shifted enantioselectivity for methyl dichlorprop ((RS)-methyl 2-(2,4-dichlorophenoxy)propionic acid) strongly towards preferentially removing the non-herbicidal enantiomer in soils from Brazil and North America, potentially increasing phytotoxicity of its residues relative to that of the racemate. Assessments of the risks chemical pollutants pose to public health and the environment need to take into account the chiral selectivity of microbial transformation processes and their alteration by environmental changes, especially for pesticides as up to 25% are chiralref.
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