4 ms·

> Then, consider how misleading the "parts per million" metric is, considering Avogadro's number. What about Avogadro's number make a PPM metric (i.e. a ratio)

> Then, consider how misleading the "parts per million" metric is, considering Avogadro's number. What about Avogadro's number make a PPM metric (i.e. a ratio) misleading??? Because there are a lot of millions in Avogadro's number? How is that relevant to a ratio?

forgotmypw 8y ago
It is misleading because "parts per million" is perceived like a very small number by the average human, while in reality one part per million is a rather substantial amount of a substance in the water.
- creddit 8y ago
  It's exactly 0.0001% of the water no matter how much water there is. Context of what the substance is and its mechanism of action would determine whether or not that "is a rather substantial amount".
rayiner 8y ago
It’s hand waving, and possibly orthorexia: https://www.eatright.org/health/diseases-and-conditions/eating-disorders/orthorexia-an-obsession-with-eating-pure https://www.eatright.org/health/diseases-and-conditions/eati.... Remember, the human immune system was designed to drink water out there in the world, which has animals pissing and shitting in it. Heavy metal pollution likewise occurs naturally. (Bangladesh, where I’m from, naturally has dangerously high levels of arsenic in the water.) Your immune system is designed to handle the “strain” of dealing with all that. We’re drinking the cleanest water humanity has ever drank (and have the highest life expectancies in human history).
- radicaldreamer 8y ago
  Humans were only "designed" to live until they reproduce and the human lifespan was far, far shorter until the last few hundred years. Just because it's possible to live till 25 and drink arsenic laced water, it doesn't mean it's good to do so.
  - jimmy1 8y ago
    You have kidneys, a liver, and a lymphatic system that all work wonders against small invaders in small quantities, perfect for the situation described with the "PPM" metric. We all love buying into these "it's xyz killing me!" stories but whats most likely causing you to feel terrible or potentially killing you is your lack of (quality) sleep, excess of stress, poor diet or potentially a combination of all three. And if I may throw my two cents in, humans were "designed" to live right around somewhere in the 60-70 range. This has been true since we kept track of humans, at least.
  - stouset 8y ago
    The human lifespan was only “far, far shorter” because of infant mortality and childhood disease. The overwhelming increase in lifespan gains in this time frame have to do with infants making it to adulthood, not adults becoming elderly.
- orf 8y ago
  What about pollutants that have only existed for the last 50 years?
- willj 8y ago
  Citation for "designed to handle the strain" of heavy metals?
- mikekchar 8y ago
  I'm not sure if you really mean "designed". Some people literally believe that to be true. If that's what you meant, then my useful contribution to the conversation will end here :-). If not, and you mean "evolved", then evolution does not necessarily select for a global maximum. It's very likely that instead of "best", you will get "good enough". If it's enough to cause you not to die, then that's fine, generally. Here's an example. If you get some baker's yeast an put it in sugar water and then add a little bit of salt, most of the yeast will not die. However, it will struggle. If you maintain that yeast, in your lifetime it will likely not adapt to the salt, but neither will it grow well. There are yeasts that are adapted to salt, so if they happen to get in there, they will take over. However, if they are not around, the baker's yeast that is struggling there may never adapt to the salt. The mutations that would provide salt adaptation are not guaranteed. It may continue to struggle for aeons. It would be silly to say that it's OK to add salt to the yeast simply because it has lived for a long time in a salty environment. The salt is still bad for it. Just to be clear, just because we evolved in an environment that contains something does not mean that our bodies evolved to handle that problem efficiently. It just wasn't bad enough to kill us off. Similarly (because I see this with diet conversations all the time), the fact that our diet was one way a long time ago, does not in itself suggest that this is a healthy diet. It just means that it wasn't bad enough to kill us off.
- deleted 8y ago
  [deleted]

forgotmypw 8y ago

It is misleading because "parts per million" is perceived like a very small number by the average human, while in reality one part per million is a rather substantial amount of a substance in the water.

creddit 8y ago
It's exactly 0.0001% of the water no matter how much water there is. Context of what the substance is and its mechanism of action would determine whether or not that "is a rather substantial amount".

rayiner 8y ago

It’s hand waving, and possibly orthorexia: https://www.eatright.org/health/diseases-and-conditions/eating-disorders/orthorexia-an-obsession-with-eating-pure https://www.eatright.org/health/diseases-and-conditions/eati.... Remember, the human immune system was designed to drink water out there in the world, which has animals pissing and shitting in it. Heavy metal pollution likewise occurs naturally. (Bangladesh, where I’m from, naturally has dangerously high levels of arsenic in the water.) Your immune system is designed to handle the “strain” of dealing with all that. We’re drinking the cleanest water humanity has ever drank (and have the highest life expectancies in human history).

radicaldreamer 8y ago
Humans were only "designed" to live until they reproduce and the human lifespan was far, far shorter until the last few hundred years. Just because it's possible to live till 25 and drink arsenic laced water, it doesn't mean it's good to do so.
- jimmy1 8y ago
  You have kidneys, a liver, and a lymphatic system that all work wonders against small invaders in small quantities, perfect for the situation described with the "PPM" metric. We all love buying into these "it's xyz killing me!" stories but whats most likely causing you to feel terrible or potentially killing you is your lack of (quality) sleep, excess of stress, poor diet or potentially a combination of all three. And if I may throw my two cents in, humans were "designed" to live right around somewhere in the 60-70 range. This has been true since we kept track of humans, at least.
- stouset 8y ago
  The human lifespan was only “far, far shorter” because of infant mortality and childhood disease. The overwhelming increase in lifespan gains in this time frame have to do with infants making it to adulthood, not adults becoming elderly.
orf 8y ago
What about pollutants that have only existed for the last 50 years?
willj 8y ago
Citation for "designed to handle the strain" of heavy metals?
mikekchar 8y ago
I'm not sure if you really mean "designed". Some people literally believe that to be true. If that's what you meant, then my useful contribution to the conversation will end here :-). If not, and you mean "evolved", then evolution does not necessarily select for a global maximum. It's very likely that instead of "best", you will get "good enough". If it's enough to cause you not to die, then that's fine, generally. Here's an example. If you get some baker's yeast an put it in sugar water and then add a little bit of salt, most of the yeast will not die. However, it will struggle. If you maintain that yeast, in your lifetime it will likely not adapt to the salt, but neither will it grow well. There are yeasts that are adapted to salt, so if they happen to get in there, they will take over. However, if they are not around, the baker's yeast that is struggling there may never adapt to the salt. The mutations that would provide salt adaptation are not guaranteed. It may continue to struggle for aeons. It would be silly to say that it's OK to add salt to the yeast simply because it has lived for a long time in a salty environment. The salt is still bad for it. Just to be clear, just because we evolved in an environment that contains something does not mean that our bodies evolved to handle that problem efficiently. It just wasn't bad enough to kill us off. Similarly (because I see this with diet conversations all the time), the fact that our diet was one way a long time ago, does not in itself suggest that this is a healthy diet. It just means that it wasn't bad enough to kill us off.
deleted 8y ago
[deleted]