Evaluation of the relative toxicity of active ingredients versus formulation products

Initial testing conducted to evaluate the potential effects of pesticides on honey bees utilizes technical grade active ingredient. When the pesticides are applied in the field they are part of a formulation or “end use product.” Higher tier studies required by the US EPA often use formulated, end use products under more realistic application conditions in the field, as well as technical grade active ingredient such as in whole colony feeding studies. Some researchers have questioned whether the active ingredient tests represent the potential toxicity of the end use product. To evaluate the relative toxicity of active ingredients versus end-use formulations, the PRTF developed and evaluated a database of laboratory studies conducted with both types of test substances.

The database contained acute oral and contact data for approximately 150 different chemicals and formulated products. The chemicals were classified according to their toxicity (high, medium, low) and the question “How often is the toxicity of the formulation significantly different from that of the active ingredient?”

Result of Comparison

Contact Toxicity

Oral Toxicity

Same toxicity category



A.I. more toxic than formulation



Formulation more toxic than A.I.



Results and Conclusions

The results of this comparison indicated that the toxicity of the formulations was rarely significantly different from that of the technical grade active ingredient. This indicates that the results of testing conducted using the technical grade active ingredient are adequate and protective of non-target species for use in Tier 1 risk assessment.