A very useful comment is copied below. This is from a web listserv about lab safety:
Caveat: published data, especially from authorities such as EPA and NIOSH, tends to acquire an aura of sanctity. I would urge everyone to remember that there are huge differences -- as in, a couple of orders of magnitude -- in the odor sensitivity between various persons. Some persons have practically no sense of smell. Published odor thresholds should be regarded as standard values in the middle of a very wide bell curve. Real-world correlation is low. This also accounts for the considerable divergence I have seen among various sources.
Another site list odor thresholds for substances dissolved in water, as ppb levels. This is a very different list than above, but perhaps more useful in some situations.