Figure 1

Experimental protocol and block design for the two-stage carcinogenesis model to assess GMA-SS welding PM as a tumor promoter in A/J mice. Mice were IP injected with MCA (initiator) or corn oil (vehicle) then 1 week later exposed to GMA-SS (340 or 680 μg) or PBS (vehicle; sham) by pharyngeal aspiration once a week for 5 weeks. The study was carried out in four blocks (1 block/day for 4 days/week) for randomization. All treatment combinations were represented in each block. Body weights were recorded at week 0, then at each weekly aspiration exposure and at every two weeks thereafter. Mice were sacrificed 30 weeks post-initiation and tumor multiplicity was evaluated.