I fw this abstract because if this is the state of chemical 
toxicology after several decades of development, what do you think is 
the state of development of protocols to test GMOs after only 1 
decade, with concerted suppression of efforts to get anywhere in 
scientific assessments?


SEMINAR NOTICE - Bio-Protection and Ecology Division, Lincoln

   Prof. John Stark, Washington State University, USA

  Toxicity endpoints used in risk assessment: what do they really mean?

ABSTRACT:  Acute lethal concentration estimates (LC50) are the
most widely developed measure of toxicity and are often used in
the ecological risk assessment process for the protection of
threatened and endangered species.  Uncertainty factors such as
1/20th of the LC50 are also used to compensate for a lack of
knowledge of the impacts that pesticides and other toxicants might
have on particular species.  Exposure to toxicants can cause
multiple sublethal effects.  Therefore, the LC50 may be woefully
inadequate as a measure of effect on populations.  Recent studies
have shown that LC50s cannot be compared among species to
predict population-level outcomes because of differences in life
history variables.  For some species, 50% mortality will result in
significant population declines, while for others, 50% mortality will
only slow population growth slightly.  In other words, 50% mortality
or 50% reduction in fecundity does not mean the same thing for all
species.  In this presentation, measures of toxicity based on
individuals will be compared to effects on actual populations.  A
modeling approach will also be used to show possible outcomes of
lethal and sublethal effects on populations.
   The value of various endpoints of toxicity for prediction of 
population effect will be