ignores things like how quickly different materials are shed from the body
Seems like a reasonable thing to do, given which substances we’re discussing. Lead‘s half-life for leaving the body is several decades — it’s a fair approximation to say that it does not leave the body.
Proposition 65 isn’t just lead, though, it’s anything that causes cancer or birth defects. For example, formaldehyde has a half life of minutes. If you imagine a substance similar to formaldehyde that decayed much more slowly, it would obviously make sense to have a lower limit.
Seems like a reasonable thing to do, given which substances we’re discussing. Lead‘s half-life for leaving the body is several decades — it’s a fair approximation to say that it does not leave the body.
Proposition 65 isn’t just lead, though, it’s anything that causes cancer or birth defects. For example, formaldehyde has a half life of minutes. If you imagine a substance similar to formaldehyde that decayed much more slowly, it would obviously make sense to have a lower limit.