Accounting for multiple comparisons in statistical analysis of the extensive bioassay data on glyphosate

Glyphosate is a widely used herbicide worldwide. In 2015, the International Agency for Research on Cancer (IARC) reviewed glyphosate cancer bioassays and human studies, declared that the evidence for carcinogenicity of glyphosate is sufficient in experimental animals.  We analyzed ten glyphosate rodent bioassays, including those in which IARC found evidence of carcinogenicity, using a meta-analytic procedure that adjusts for the large number of tumors eligible for statistical testing and provides valid false-positive probabilities.  The test statistics for these global tests are functions of p-values from a standard test for dose-response trends applied to each specific type of tumor.  We evaluated three global tests, using as test statistics the smallest p-value from a standard statistical test for dose-response trend and the number of such tests for which the p-value is less than or equal to 0.05 or 0.01.  The false-positive probabilities obtained from two implementations of these thr...