1. etal (13) we can identify an illuminating performed with the 2000 3000 and 4500
2. relationship (Figure 2). If the total cumula- ppm dose levels for longer times to test this
3. tive dose were important in producing an hypothesis more fully. For the 9-week
4. effect (on testicular histopathology in this exposure used here we saw no observable
5. case but it could be any effect: sperm pro- effects at 2000 ppm and at least some toxi