WHO Mercury Exposure Standards: Evaluating Inhalation Risk

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Discussion Overview

The discussion revolves around the World Health Organization (WHO) standards for mercury exposure, specifically focusing on inhalation risks associated with inorganic mercury. Participants explore the implications of the WHO's occupational exposure limits and acceptable daily intake (ADI) values, examining how these relate to actual exposure scenarios.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant presents WHO standards stating that the occupational exposure limit for inorganic mercury is 50 µg/m3 and the ADI is 40 µg/day, questioning how these figures correlate with actual inhalation exposure.
  • Another participant requests sources for the WHO article and the statistic regarding 50 µg/m3 of mercury in the air, indicating a need for verification of claims made.
  • Several participants express uncertainty about what constitutes a safe amount of inorganic mercury inhaled daily, highlighting a lack of consensus on safety levels.
  • A later reply suggests that the initial calculation of mercury intake may be too high, emphasizing that occupational exposure is averaged over an 8-hour workday and not continuous, which could affect the interpretation of the data.
  • One participant notes that the ADI considers lifetime exposure from various sources, including air and food, and suggests that the figure should be adjusted based on body weight to reflect individual differences.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the safety of inhaling inorganic mercury or the implications of the WHO standards. Multiple competing views and interpretations of the data remain unresolved.

Contextual Notes

Participants mention the need to consider time-averaged exposure and body weight when discussing mercury intake, indicating that assumptions about exposure duration and individual variability are important but not fully resolved in the discussion.

Yuri B.
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2 statements from an article :

"WHO standards for occupational exposure to inorganic mercury are currently 50 µg/m3 in air ...

WHO's maximum acceptable daily intake (ADI) for mercury is 40 µg/day."

An average person inhaling 20 m3 of the air containing 50 µg/m3 of mercury, inhales actually 1000 µg of mercury per day. 80 % of inhaled mercury vapours is absorbed by organism, thus making the daily intake of 800 µg. How it correlates with the statements cited ?
 
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Please post a link both to the WHO article and whatever article you got the statistic regarding 50ug/m3 of mercury in the air.
 
Who knows what is safe amount of inorganic mercury breathed daily ?
 
Yuri B. said:
Who knows what is safe amount of inorganic mercury breathed daily ?

Please post the links that Ryan has asked for, so that this thread can proceed.
 
Yuri B. said:
occupational exposure
"Apples."
Yuri B. said:
acceptable daily intake (ADI)
"Oranges."
 
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Exposure or Absorption and the Crucial Question of Limits for Mercury
Derek W. Jones, PhD, FIM, CChem., FRSC(UK), FBSE

ABSTRACT
 
Yuri B. said:
Exposure or Absorption and the Crucial Question of Limits for Mercury
Derek W. Jones, PhD, FIM, CChem., FRSC(UK), FBSE

ABSTRACT

Can you provide a link please? :-)
 
Here is the abstract, but it seems to be food related rather than air born mercury. It seems to be primarily in defense of dental amalgams. The OP may need to get the url from the complete document. It was rather difficult to copy this link for some reason.

https://www.cda-adc.ca/jcda/vol-65/issue-1/42.html
 
Yuri B. said:
2 statements from an article :

"WHO standards for occupational exposure to inorganic mercury are currently 50 µg/m3 in air ...

WHO's maximum acceptable daily intake (ADI) for mercury is 40 µg/day."

An average person inhaling 20 m3 of the air containing 50 µg/m3 of mercury, inhales actually 1000 µg of mercury per day. 80 % of inhaled mercury vapours is absorbed by organism, thus making the daily intake of 800 µg. How it correlates with the statements cited ?

As Bystander metioned, this is apples and oranges.

Ocupational exposure would be time averaged over an 8 hour work day, 5 days of the week. The calculation has to take this into account since a person does not work 24 hours a day, seven days a week.. Your 800 ug is way too high. Of course, maximum levels of mercury in breathable air are probably in the literature, above which symtoms of "poisoning" by the substance would manifest in the short term. To be safe, the wearing wearing of a respiratory mask would be necessary, probably above the 50 µg/m3 that you have quoted, which would be standard, or should be, if they follow along with WHO, for most countries in their ocupational hazard guidlines and laws as allowable limit for mercury in the air.

ADI is for exposure during a lifetime, which would take into account all exposure to mercury - ie by air, by food, by contact. Below the ADI, a person should not develop any symptoms of disease or ill effects from the exposure to the substance. By the way, the actual figure should be µg/kg of body weight/day to take into account the size of the individual. 40 µg/day would be for a person weighing 100kg.
 

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