Table 1 Maximum allowable concentrations (MAC) for heavy metals of concern.

No.	Heavy metal	Symbole	Maximum Allowable Concentration (MAC) (mg/L)			Potential health risk (UEPA)	Risk type
No.	Heavy metal	Symbole	KSA^a	USEPA	Health Canada	Potential health risk (UEPA)	Risk type
1	Barium	Ba	1.3	7.0^b	2.0^c	Ingestion	Non-cancer
2.	Boron	B	2.4	-	5.0^d	Ingestion and inhalation	Non-cancer
3	Cadmium	Cd	0.003	0.005^e	0.007^f	Ingestion and inhalation	Cancer and non-cancer
4	Chromium	Cr	0.05	0.1^g	0.05^h	Ingestion, dermal, inhalation	Cancer and non-cancer
5	Lithium	Li	-	0.01ⁱ	-	Ingestion	Non-cancer
6	Manganese	Mn	0.4	-	0.1^j	Ingestion	Non-cancer
7	Strontium	Sr	-	-	7.0^k	Ingestion	Non-cancer
8	Zinc	Zn	3.0	5.0	5.0^l	-	-

^aMEWA (2022)⁴²; ^bDWEL established by USEPA (2012)³⁹; ^cHealth Canada (2019)³⁸; ^dHealth Canada (2023)⁴³; ^eUSEPA (1991)⁴⁴; ^fHealth Canada (2020)⁴⁵;^gUSEPA (2025a)³⁰; ^hHealth Canada (2015)⁴⁶, ⁱUSEPA (2023)⁴⁷; ^jHealth Canada (2016)⁴⁸; ^kHealth Canada (2018)⁴⁹, ^lHealth Canada (1987)⁵⁰.

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