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Assessing taste and visual perception of Mn(II) and Mn(IV) (PDF)

  • Author(s): Sain, Amanda E.; Griffin, Ashley; Dietrich, Andrea M.
  • Publications: Journal - American Water Works Association
  • Issue Date: January 2014
  • Volume / Number: 106, Number 1
  • Page(s): E32-E40
  • DOI:
  • Product Number: JAW_0079043
Full Text: pdf
Expanded Summary: pdf

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The US Environmental Protection Agency secondary maximum contaminant level (SMCL) for manganese (Mn) is 0.05 mg/L, reportedly because of bitter metallic taste, black-brown particles in water, and black-brown discoloration of fixtures and laundry. This study revisited visual and taste thresholds for Mn(II) and Mn(IV) using one-in-five, one-in-three, and triangle tests for concentrations from 0.005 to 506 mg/L. Results showed that Mn(II) and Mn(IV) do not taste significantly different from distilled water at 0.05 mg/L Mn. The population taste threshold for Mn(II) from manganese sulfate is > 1,000 times the SMCL; the threshold concentration is 75-100 mg/L Mn(II) and likely is influenced by both sulfate and Mn(II) taste contribution. Aqueous Mn(II) is colorless at 0.05 mg/L and remains visually undetectable at concentrations as high as 506 mg/L; Mn(IV) is visually detectable in water at concentrations as low as 0.005 mg/L. Findings suggest that consumers cannot detect Mn(II) concentrations above the SMCL by taste or sight and that bitter and metallic descriptors for 0.05 mg/L Mn are unwarranted.

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