Problems posed by the determination of toxicity risk levels

3 Problems posed by the determination of toxic risk levels 

The quality of the determination of risk levels set by regulation depends on the quality of measurements of lethal concentrations and doses (LC and LD50). From safety data in Part Three it is seen that this quality is far from being reached. 

With data from different sources for the same animal and means of penetration the dispersion of resulte is to be taken into account. 

For Part Three multiple data was obtained with rat orally by choosing examples that provided at least three values. Forty seven substances were considered, / plying the determination criteria for the labelling code for ingestion, two different cod can be allocated, depending on the LD50, to twenty of these substances. It is even possible to allocate three different codes to one of them. 

So acrylic acid would bear R25 (LD50 o-n 34 mg/kg) R22 (LD50 o-r 235 340 353 355) or no code (LD50 o-r 2590). Benzene, toluene, 1-propanol, dichloromethane, etc., can be either R22 or have no code by ingestion depending on the values (labour regulations actually chose not to allocate any acute toxicity code to them). 

---