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Update on the Use of the Local Lymph Node Assay for End Use Pesticide Products and Adoption of the Reduced Dose Protocol for LLNA (rLLNA)

Harmonized Test Guidelines

Current as of June 2011


The Office of Pesticide Programs (OPP) is expanding the existing OPPTS 870.2600 dermal sensitization guideline from assessing only the technical grade active ingredients to include end use pesticide products using the radiolabeled (or traditional) Local Lymph Node Assay (LLNA). None of the non-radiolabeled LLNA test methods are included in this expansion. Separately, OPP is also adopting the “reduced or limit dose” LLNA (rLLNA) radiolabeled assay, which will further reduce the number of animals used in laboratory tests by 40% when compared to the multi-dose LLNA.


The objective of this policy (PDF) (7 pp, 128 K, about PDF) is to expand the usefulness the traditional (or radiolabeled) LLNA protocol for assessment of dermal sensitization potential to single component pesticide products (i.e., technical grade active ingredients) and to pesticides with multiple components (i.e., end use products). In most cases, the traditional LLNA continues to be the preferred assay because it incorporates replacement, refining, and reducing animal testing (also referred to as “the 3 R’s” or the three main goals animal testing) while also providing a more quantitative assessment of dermal sensitization in a way that is less subjective than similar guinea pig assays.


A 2001 OPPTS guideline (870.2600) lists the LLNA (which uses the mouse as the test species) as the preferred assay over the two other traditional guinea pigs assays used for dermal sensitization. These other acceptable assays are the Guinea-Pig Maximization Test (GPMT) or Buehler Test (BT). They will be used in situations where the LLNA is not applicable.


  1. Expansion of LLNA radiolabel assay to test end use pesticide products

  2. Adoption of the Reduced LLNA (rLLNA) radiolabeled test method

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