title: Uranium in drinking-water: a unique case of guideline value increases and discrepancies between chemical and radiochemical guidelines.
abstract: BACKGROUND
  Uranium represents a unique case for an element naturally present in the environment, as its chemical guideline value in drinking water significantly increased from 2 μg/L in 1998 up to 15 μg/L in 2004 and then to 30 μg/L in 2011, to date corresponding to a multiplication factor of 15 within a period of just 13 years.
  
  
  OBJECTIVE
  In this commentary we summarize the evolution of uranium guideline values in drinking-water based on both radiological and chemical aspects, emphasizing the benefit of human studies and their contribution to recent recommendations. We also propose a simpler and better consistency between radiological and chemical values.
  
  
  CONCLUSIONS
  The current chemical guideline value of 30 μg/L is still designated as provisional because of scientific uncertainties regarding uranium toxicity. During the same period, the radiological guideline for (238)U increased from 4 Bq/L to 10 Bq/L while that for (234)U decreased from 4 Bq/L to 1 Bq/L. These discrepancies are discussed here, and a value of 1 Bq/L for all uranium isotopes is proposed to be more consistent with the current chemical value of 30 μg/L.
  
  
  CONCLUSIONS
  Continuous progress in the domains of toxicology and speciation should enable a better interpretation of the biological effects of uranium in correlation with epidemiological human studies. This will certainly aid future proposals for uranium guideline values.
authors.affiliation: CEA/DEN/DRCP/CETAMA, Marcoule, F-30207 Bagnols-sur-Cèze, France. Electronic address: eric.ansoborlo@cea.fr.
authors.forename: Eric
authors.initials: E
authors.lastname: Ansoborlo
authors.affiliation: CEA/DSV/PROSITON, Cadarache, F-13115 Saint Paul-lez-Durance, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Lebaron-Jacobs
authors.affiliation: CEA/DSV/IBEB/SBTN, Marcoule, F-30207 Bagnols-sur-Cèze, France.
authors.forename: Odette
authors.initials: O
authors.lastname: Prat
mesh_terms: D060766:Drinking Water / Q000737:chemistry* / Q000592:standards; D004781:Environmental Exposure / Q000009:adverse effects; D017408:Guidelines as Topic / Q000592:standards*; D006801:Humans; D019055:No-Observed-Adverse-Effect Level; D012016:Reference Values; D013997:Time Factors; D014501:Uranium / Q000032:analysis / Q000592:standards* / Q000633:toxicity; D014875:Water Pollutants, Radioactive / Q000032:analysis / Q000592:standards* / Q000633:toxicity; D014944:World Health Organization
chemical_list: D060766:Drinking Water; D014875:Water Pollutants, Radioactive; D014501:Uranium
keywords: Drinking-water; Epidemiology; Guidelines; Toxicity; Uranium