4 ms·

Saying no detectable lead is a bit hard to interpret without also listing the lower limit of detection for the measurement. I assume based on the sig figs it mi

by s0rce 6y ago

Saying no detectable lead is a bit hard to interpret without also listing the lower limit of detection for the measurement. I assume based on the sig figs it might be less than 0.5 ppt or something around that. Is 1 ppt lead really bad for you? There is lead in everything, see: https://www.fda.gov/food/metals-and-your-food/lead-food-foodwares-and-dietary-supplements https://www.fda.gov/food/metals-and-your-food/lead-food-food..., note many of the LOD reported there are 1000x higher...

jeffbee 6y ago
There is not a known-safe level of lead.
- londons_explore 6y ago
  But there is a level where the cost of water treatment by far outweighs the health impacts of an atom of lead remaining... The question is where is that level?...
  - jeffbee 6y ago
    Isn't that trade-off already made on the CDC guidance of 5µg/dL? This is pretty much an economic decision, because the reference value is changed to match the .975 quantile of blood lead observations. It was 10µg/dL until 2012.
- throwaway0a5e 6y ago
  Which is also a useless statement without knowing the lower threshold for measurement. There certainly exists an amount of lead that's safe. One molecule won't harm you. Two won't either. But where the limit is nobody knows. And nobody will know for a long time because current trends in lead exposure are rife with confounding factors (i.e. poverty) and the proliferation of statements like "no safe level" dis-incentivize research (finding a number won't matter if nobody cares about your number because "there's no safe level).
  - jeffbee 6y ago
    No, you are misinterpreting the situation. Blood lead levels have a linear relationship with decreased cognitive function. The least detectable levels of lead have measurable impact on mental development. You can't say that "one molecule won't harm you" because you don't know that and all the evidence we have indicates you are wrong. 1 molecule may very well equal 1 fucked-up synapse.
    - Scoundreller 6y ago
      > Blood lead levels have a linear relationship with decreased cognitive function. I've read the opposite: > It is also critical to note research indicates the relationship between BLLs and IQ deficits is not linear; rather, the first small elevation of BLL in young children apparently causes most of the neurological damage, with additional higher exposures causing disproportionately less additional IQ reduction (Maas, 2005). p. 20: https://www.hamilton.ca/sites/default/files/media/browser/2015-11-13/proposed_corrosion_control_plan.pdf https://www.hamilton.ca/sites/default/files/media/browser/20... Mass, 2005: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1497727/pdf/16134575.pdf https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1497727/pdf/161... (ugh, which just refers to another source for the statement).
      - jeffbee 6y ago
        Well, you got me on the English usage point. I need a word other than "linear". What I am trying to communicate is there is no threshold, nor is there a beneficial amount, like there is with other metals like copper. You should eat a milligram of copper. You may eat a gram of copper and nothing will happen. If you eat a kilo of copper, you'll die. There isn't any amount of lead so small that it will leave you unharmed.

by s0rce 6y ago

jeffbee 6y ago

There is not a known-safe level of lead.

londons_explore 6y ago
But there is a level where the cost of water treatment by far outweighs the health impacts of an atom of lead remaining... The question is where is that level?...
- jeffbee 6y ago
  Isn't that trade-off already made on the CDC guidance of 5µg/dL? This is pretty much an economic decision, because the reference value is changed to match the .975 quantile of blood lead observations. It was 10µg/dL until 2012.
throwaway0a5e 6y ago
Which is also a useless statement without knowing the lower threshold for measurement. There certainly exists an amount of lead that's safe. One molecule won't harm you. Two won't either. But where the limit is nobody knows. And nobody will know for a long time because current trends in lead exposure are rife with confounding factors (i.e. poverty) and the proliferation of statements like "no safe level" dis-incentivize research (finding a number won't matter if nobody cares about your number because "there's no safe level).
- jeffbee 6y ago
  No, you are misinterpreting the situation. Blood lead levels have a linear relationship with decreased cognitive function. The least detectable levels of lead have measurable impact on mental development. You can't say that "one molecule won't harm you" because you don't know that and all the evidence we have indicates you are wrong. 1 molecule may very well equal 1 fucked-up synapse.
  - Scoundreller 6y ago
    > Blood lead levels have a linear relationship with decreased cognitive function. I've read the opposite: > It is also critical to note research indicates the relationship between BLLs and IQ deficits is not linear; rather, the first small elevation of BLL in young children apparently causes most of the neurological damage, with additional higher exposures causing disproportionately less additional IQ reduction (Maas, 2005). p. 20: https://www.hamilton.ca/sites/default/files/media/browser/2015-11-13/proposed_corrosion_control_plan.pdf https://www.hamilton.ca/sites/default/files/media/browser/20... Mass, 2005: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1497727/pdf/16134575.pdf https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1497727/pdf/161... (ugh, which just refers to another source for the statement).
    - jeffbee 6y ago
      Well, you got me on the English usage point. I need a word other than "linear". What I am trying to communicate is there is no threshold, nor is there a beneficial amount, like there is with other metals like copper. You should eat a milligram of copper. You may eat a gram of copper and nothing will happen. If you eat a kilo of copper, you'll die. There isn't any amount of lead so small that it will leave you unharmed.