Wikipedia:Reference desk/Archives/Science/2020 August 29

= August 29 =

Confused about how much lead is in our bodies
I'm confused about a sentence in the Lead poisoning article:

"Since the normal Pb$2+$ concentration in the extracellular fluid is low (the adult average is 120mg but rates vary greatly by country.), even a low increase in Pb$2+$ concentration has a significant positive effect on the blockage of NMDA-receptors."

The article talks about how there is no safe amount of lead exposure and "Lead has no known physiologically relevant role in the body", then says our bodies contain 120 mg, which seems like a lot. I don't know how to access the cited source and I'm having trouble finding a resource that confirms that we have that much lead in our bodies. Can anyone clear up the confusion? Cheesycow5 (talk) 15:38, 29 August 2020 (UTC)


 * I agree it is confusing, and I wonder if it is correct. It is strange to quote a mass as representing a concentration. Estimating the body weight of an adult non-elderly male at 75 kg, and using the formulas from Extracellular fluid and Body water, the amount of extracellular fluid should be something like 60% of 75 kg × 0.6 = 27 kg. 120mg on 27kg is 4.4 mg/L. For comparison: the article Lead poisoning states: "Authorities such as the American Academy of Pediatrics define lead poisoning as blood lead levels higher than 10 μg/dL."18 That amounts to 0.1 mg/L. The link to the cited source does not work, and "World Health Organization 2000" is not enough to identify the specific publication. The WHO publication Nutrients in Drinking Water does mention "120mg/L" several times, but each time for the concentration of sodium, and not as an average but as a ceiling.  --Lambiam 17:39, 29 August 2020 (UTC)


 * Thanks for the detective work. I'm guessing, in any case, it should be removed since it doesn't properly cite a source for the claim. Cheesycow5 (talk) 18:37, 29 August 2020 (UTC)
 * I went ahead and removed that sentence. Cheesycow5 (talk) 21:01, 29 August 2020 (UTC)
 * There's an error somewhere, arithmetic is wrong. Sagittarian Milky Way (talk) 00:46, 30 August 2020 (UTC)