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Politics of toxicity

  • 14/06/2005

In theory, LD 50 and acceptable daily intake provide reliable estimate of how much of a particular toxin an average person can be safely exposed to. But in practice, this method is highly inadequate: it does not consider the cocktail of numerous pesticides most people carry. So while individually every pesticide in blood samples might be within safe limits, the effect of total mix might yet be lethal. Risk assessments also do not consider other factors influencing individual susceptibility such as nutrition, infectious agents and socio-economic variables. Moreover, the studies use theoretical "uncertainty factors' that do not reflect real differences between laboratory animals and humans. Also overlooked is the undue influence of pesticides' manufacturers and users on agencies conducting risk assessments. These make the risk-assessment process less than purely scientific. Using such an approach to determine "acceptable' exposure to a single pesticide, or even a class of pesticides, results in policy decisions that do not adequately protect public health.

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