Urgent need to reevaluate the latest World Health Organization guidelines for toxic inorganic substances in drinking water

Abstract

The World Health Organization (WHO) has established guidelines for drinking-water quality that cover biological and chemical hazards from both natural and anthropogenic sources. In the most recent edition of Guidelines for Drinking-water Quality (2011), the WHO withdrew, suspended, did not establish, or raised guidelines for the inorganic toxic substances manganese, molybdenum, nitrite, aluminum, boron, nickel, uranium, mercury, and selenium. In this paper, we review these changes to the WHO drinking-water guidelines, examining in detail the material presented in the WHO background documents for each of these toxic substances. In some cases, these WHO background documents use literature reviews that do not take into account scientific research published within the last 10 or more years. In addition, there are instances in which standard WHO practices for deriving guidelines are not used; for example, rounding and other mathematical errors are made. According to published meeting reports from the WHO Chemical Aspects Working Group, the WHO has a timetable for revising some of its guidelines for drinking-water quality, but for many of these toxic substances the planned changes are minimal or will be delayed for as long as 5 years. Given the limited nature of the planned WHO revisions to the inorganic toxic substances and the extended timetable for these revisions, we suggest that governments, researchers, and other stakeholders might establish independent recommendations for inorganic toxic substances and possibly other chemicals to proactively protect public health, or at the very least, revert to previous editions of the Guidelines for Drinking-water Quality, which were more protective of public health.

The Sealing Step in Aluminum Anodizing: A Focus on Sustainable Strategies for Enhancing Both Energy Efficiency and Corrosion Resistance

“…Molybdates are generally classified as a low toxicity substance to humans [259,[472][473][474][475][476][477][478] with its tolerable upper intake level (UL) of set at 2 mg/day for humans [479,480] and its content in drinking water limited to 70 ug/L [481][482][483][484]. Although molybdenum might be considered to be less toxic to humans, it is reported to be toxic to certain marine organisms [485][486][487][488][489] with its toxicity related to the solubility of the molybdenum compounds.…”

Health risk assessment of environmental selenium: Emerging evidence and challenges

“…Finally, the largest of the selenium RCTs, SELECT (23), whose overall selenium intake in the supplemented group averaged 300 µg/day (15), has shown that such amount of exposure induces ‘minor’ adverse effects such as dermatitis and alopecia [a long-recognized sign of selenium toxicity (12)]. These effects indicate that the selenium lower-observed-adverse-effect-level (LOAEL) is much lower than previously considered by regulatory agencies (5,54), which could base their assessment on the scarce data yielded by a few old Chinese environmental studies (55), calling for an update of the risk assessment of this element (5,15,56,57). …”

Evaluating the effects between metal mixtures and serum vaccine antibody concentrations in children: a prospective birth cohort study

“…The WHO discontinued its previous health-based guideline of 400 μg/L for W-Mn in 2011 based on the judgement that such exposure levels are uncommon [83]. However, results from our study and evidence from other regions in Bangladesh and numerous other countries demonstrate that, in fact, high exposure levels can be common in certain populations [84].. Because W-Mn is thought to be more bioavailable than other dietary sources of manganese among populations with ricebased diets such as Bangladesh [85], it is likely that the elevated W-Mn of women and children in this cohort represents an important source of manganese exposure. As manganese is an important metal involved with nutritional immunity, future studies should explore whether the nutrition of certain subpopulations (e.g.…”