3 ms·

One of the arguments in the book I mentioned was that yes the trace amounts are "safe", but in some cases the body cannot detox certain synthetic chemicals, so

by wppick 8y ago

One of the arguments in the book I mentioned was that yes the trace amounts are "safe", but in some cases the body cannot detox certain synthetic chemicals, so they build up in the body until they reach a level that begins to cause health issues

Bartweiss 8y ago
Broadly, this corresponds to the use "threshold model" and "linear no-threshold model" in toxicology, which describe whether the risk/harm from a substance has a safe 'cliff' or declines smoothly down to 0 dose. It's well understood that carcinogens are LNT hazards. The old quip that "even breathing causes cancer" is literally true, so there's no such thing as a safe dose of a carcinogen, just an acceptable dose. (Interestingly, effectively-safe doses decline as lifespans - and therefore cumulative risk - rise.) Increasingly, we seem to be finding that non-carcinogenic risks which have been filed under 'threshold' are actually LNT threats for which the low-end risk gets lost in other noise. I'm not particularly sold on the 'synthetic' framing here, though. Lead exposure is almost certainly LNT at least in childhood. Copper and zinc are linked to Alzheimer's in some uncertain-but-suspicious way. While endocrine disruptors like BPA are synthetic, they're acting on the same pathways as 'natural' disruptors like phytoestrogens. 2.5nm particulate pollution now appears to be not only carcinogenic but also development-inhibiting; the primary sources are man-made but the primary agents (NOx, SO2) are naturally occurring at much lower doses. Very broadly, I do expect many thing we're exposed to today will eventually be viewed as horrible errors like leaded gasoline (if hopefully less severe). But I'm not sure 'synthetic' is a meaningful metric, and I'm not sure bioaccumulation of the compound is actually a very common pathway relative to accumulative damage.

by wppick 8y ago

Bartweiss 8y ago

Broadly, this corresponds to the use "threshold model" and "linear no-threshold model" in toxicology, which describe whether the risk/harm from a substance has a safe 'cliff' or declines smoothly down to 0 dose. It's well understood that carcinogens are LNT hazards. The old quip that "even breathing causes cancer" is literally true, so there's no such thing as a safe dose of a carcinogen, just an acceptable dose. (Interestingly, effectively-safe doses decline as lifespans - and therefore cumulative risk - rise.) Increasingly, we seem to be finding that non-carcinogenic risks which have been filed under 'threshold' are actually LNT threats for which the low-end risk gets lost in other noise. I'm not particularly sold on the 'synthetic' framing here, though. Lead exposure is almost certainly LNT at least in childhood. Copper and zinc are linked to Alzheimer's in some uncertain-but-suspicious way. While endocrine disruptors like BPA are synthetic, they're acting on the same pathways as 'natural' disruptors like phytoestrogens. 2.5nm particulate pollution now appears to be not only carcinogenic but also development-inhibiting; the primary sources are man-made but the primary agents (NOx, SO2) are naturally occurring at much lower doses. Very broadly, I do expect many thing we're exposed to today will eventually be viewed as horrible errors like leaded gasoline (if hopefully less severe). But I'm not sure 'synthetic' is a meaningful metric, and I'm not sure bioaccumulation of the compound is actually a very common pathway relative to accumulative damage.