Guidelines for Canadian drinking water quality boron: International considerations
The World Health Organization (WHO), U.S. EPA, Australia's National Health and Medical Research Council and the European Commission have developed guidelines or advisory values for boron in drinking water (Table 6). WHO (2011), Australia (NHMRC and NRMCC, 2011) and the European Commission (2020) have set guidelines for boron in drinking water of 2.4, 4 and 1.5 to 2.4 mg/L, respectively. The U.S. EPA does not have a maximum contaminant level (MCL) for boron in drinking water but has established a non-enforceable lifetime health advisory of 5 mg/L (U.S. EPA, 2008). Health advisories serve as informal technical guidance for unregulated drinking water contaminants in the United States. All organizations' values used decreased rat body weights as the critical effect. The differences in the values are attributable to differences in uncertainty factors, allocation factors, body weights and use of BMD modelling versus the NOAEL approach.
| Agency | Year | Value (mg/L) | Basis (critical effect, POD and UF) |
|---|---|---|---|
| Regulatory values | |||
|
2011 |
2.4 |
Critical effect: decreased body weight in rat developmental studies (Heindel et al., 1992, 1994; Price et al 1996), BMD modelling from Allen et al (1996); BMD05 = 10.3 mg/kg bw per day TDI = 0.17 mg/kg bw per day UF = 60 (interspecies = 10; intraspecies = 6) |
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AustraliaTable 6 Footnote 2 |
2011 |
4 |
Critical effect (based on WHO (2004)): decreased body weight in rat developmental study (Price et al., 1996); NOAEL = 9.6 mg/kg bw per day Adjusted TDI = 0.13 mg/kg bw per day (derived by subtracting background dietary and consumer product boron intake (0.03 mg kg bw per day) from a TDI of 0.16 mg kg bw per day) UF = 60 (interspecies = 10; intraspecies = 6) |
|
European CommissionTable 6 Footnote 3 |
2020 |
1.5 to 2.4 |
Information not available |
| Non-regulatory values | |||
|
U.S. EPATable 6 Footnote 4 |
2008 |
5 (lifetime health advisory) |
Critical effect: decreased body weight in rat developmental studies (Heindel et al., 1992, 1994; Price et al 1996), BMD modelling from Allen et al (1996); BMD05 = 10.3 mg/kg bw per day RfD = 0.2 mg/kg bw per day UF = 66 (interspecies = 10.5; intraspecies = 6.3) |
BMD – benchmark dose; BMD05 – benchmark dose corresponding to a 5% increase in adverse effect over background rates; bw – body weight; NOAEL – no adverse effect level; POD – point of departure; RfD – reference dose; TDI – tolerable daily intake; UF – uncertainty factor; U.S. EPA – United States Environmental Protection Agency; WHO – World Health Organization
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