3 ms·

Current air pollution levels isn’t indicative of lifetime or especially childhood exposure. Leaded gas for example has seen a huge decline, but was still a thi

by Retric 3y ago

Current air pollution levels isn’t indicative of lifetime or especially childhood exposure. Leaded gas for example has seen a huge decline, but was still a thing when current 70+ year olds where young. Similarly, current developing economies where very different 50 years ago.

beAbU 3y ago
Leaded gas was a thing when current 30 year olds were young.
- smcin 3y ago
  Surely studies could get a good control group of people who grew up in rural Montana, or the Andes. Assume we can find groups with near-zero lifetime exposure to atmospheric (and/or waterborne) lead. What's their background rate of Alzheimer's?
- prepend 3y ago
  Not really [0], leaded gas was completely banned in the US in 1996 but really hadn’t been used since the early 80s and had start the phase out in 1996. So you’d probably need to look at people in their 50s who really had an impact of lead from auto fuel. [0] https://www.greencarreports.com/news/1133434_why-did-the-world-use-leaded-gas-and-why-did-it-take-so-long-to-phase-out https://www.greencarreports.com/news/1133434_why-did-the-wor...
  - argiopetech 3y ago
    Where "completely" in this case implies "for road-going vehicles". General aviation (largely small, piston-engine planes) still overwhelmingly run on 100 octane low-lead (100LL).
    - matthewdgreen 3y ago
      This is a very big deal if you spend time around small aircraft (hangar floors in particular sometimes have terrifyingly high lead levels.) But if you’re not spending time close to aircraft, the amount of lead you’ll be exposed to is negligible - at least compared to auto emissions, which were ubiquitous and extremely concentrated in residential neighborhoods. Unfortunately the lead remains in the soil, so there’s still exposure to it today.
    - prepend 3y ago
      Good point. I meant “completely” for consumer vehicles in the US. That’s what was pumping out all that lead into the air in the US. The other uses were much smaller.
  - debatem1 3y ago
    Leaded gas is still not banned today. I have a car which only consumes leaded race gas and while it is surely expensive it is definitely not illegal.
    - digitalsushi 3y ago
      Many smaller, older aircraft use leaded fuel as well.
      - klunkz 3y ago
        Basically most piston engine aircraft use Avgas 100LL (low lead solution). So the majority of the air traffic found at a typical municipal airport. Fortunately this is being phased out by the FAA in favor of unleaded.
    - GenerWork 3y ago
      On road use is banned. Also, the cost per gallon of leaded gas is at least $10/gallon now, which is a pretty large incentive enough for people not to use it :)
  - bigbillheck 3y ago
    > really hadn’t been used since the early 80s I had summer jobs at gas stations in the early 90s and maybe 10% of the fuel sold was leaded.
bparsons 3y ago
This is correct. Environmental accumulation would be highest in the areas that industrialized first.
Anotheroneagain 3y ago
Romans used lead everywhere, even for cooking. Roman bones also show much higher levels of copper. It is well documented that the brains suffering from Alzheimer's lack copper. (from autopsies)
A_D_E_P_T 3y ago
Sure, but even so it's not clear that air pollution is a factor. Some researchers recently compiled a "chronology of global air quality" which might be worth a review to see if any correlations can be uncovered. At a glance, it looks to me as though Europe and the USA cleaned up their act a long time ago -- so unless pollution exposure in early childhood is somehow especially bad, pollution still has no explanatory power: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7536029/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7536029/ There's also a paper which reviews the "global incidence of young-onset dementia" -- and, again, incidence in the low-pollution USA is higher than in high-pollution developing countries. https://alz-journals.onlinelibrary.wiley.com/doi/full/10.1002/alz.12695 https://alz-journals.onlinelibrary.wiley.com/doi/full/10.100...

by Retric 3y ago

beAbU 3y ago

Leaded gas was a thing when current 30 year olds were young.

smcin 3y ago
Surely studies could get a good control group of people who grew up in rural Montana, or the Andes. Assume we can find groups with near-zero lifetime exposure to atmospheric (and/or waterborne) lead. What's their background rate of Alzheimer's?
prepend 3y ago
Not really [0], leaded gas was completely banned in the US in 1996 but really hadn’t been used since the early 80s and had start the phase out in 1996. So you’d probably need to look at people in their 50s who really had an impact of lead from auto fuel. [0] https://www.greencarreports.com/news/1133434_why-did-the-world-use-leaded-gas-and-why-did-it-take-so-long-to-phase-out https://www.greencarreports.com/news/1133434_why-did-the-wor...
- argiopetech 3y ago
  Where "completely" in this case implies "for road-going vehicles". General aviation (largely small, piston-engine planes) still overwhelmingly run on 100 octane low-lead (100LL).
  - matthewdgreen 3y ago
    This is a very big deal if you spend time around small aircraft (hangar floors in particular sometimes have terrifyingly high lead levels.) But if you’re not spending time close to aircraft, the amount of lead you’ll be exposed to is negligible - at least compared to auto emissions, which were ubiquitous and extremely concentrated in residential neighborhoods. Unfortunately the lead remains in the soil, so there’s still exposure to it today.
  - prepend 3y ago
    Good point. I meant “completely” for consumer vehicles in the US. That’s what was pumping out all that lead into the air in the US. The other uses were much smaller.
- debatem1 3y ago
  Leaded gas is still not banned today. I have a car which only consumes leaded race gas and while it is surely expensive it is definitely not illegal.
  - digitalsushi 3y ago
    Many smaller, older aircraft use leaded fuel as well.
    - klunkz 3y ago
      Basically most piston engine aircraft use Avgas 100LL (low lead solution). So the majority of the air traffic found at a typical municipal airport. Fortunately this is being phased out by the FAA in favor of unleaded.
  - GenerWork 3y ago
    On road use is banned. Also, the cost per gallon of leaded gas is at least $10/gallon now, which is a pretty large incentive enough for people not to use it :)
- bigbillheck 3y ago
  > really hadn’t been used since the early 80s I had summer jobs at gas stations in the early 90s and maybe 10% of the fuel sold was leaded.

bparsons 3y ago

This is correct. Environmental accumulation would be highest in the areas that industrialized first.

Anotheroneagain 3y ago

Romans used lead everywhere, even for cooking. Roman bones also show much higher levels of copper. It is well documented that the brains suffering from Alzheimer's lack copper. (from autopsies)

A_D_E_P_T 3y ago

Sure, but even so it's not clear that air pollution is a factor. Some researchers recently compiled a "chronology of global air quality" which might be worth a review to see if any correlations can be uncovered. At a glance, it looks to me as though Europe and the USA cleaned up their act a long time ago -- so unless pollution exposure in early childhood is somehow especially bad, pollution still has no explanatory power: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7536029/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7536029/ There's also a paper which reviews the "global incidence of young-onset dementia" -- and, again, incidence in the low-pollution USA is higher than in high-pollution developing countries. https://alz-journals.onlinelibrary.wiley.com/doi/full/10.1002/alz.12695 https://alz-journals.onlinelibrary.wiley.com/doi/full/10.100...