For purposes of this guidance the following definition applies:

• "Herbal supplement" means a dietary supplement, as described in 21 U.S.C. 321 (ff), that contains one or more herbal ingredients (i.e., an herb or other botanical, or a concentrate, extract, or combination of an herb or other botanical). An herbal supplement may or may not contain additional non-herbal dietary ingredients (e.g., vitamins, minerals, amino acids, etc.) or excipients.

In addition, for purposes of this guidance the following limitations and conditions apply:

• This guidance is not intended to suggest that manufacturers should establish specifications for any or all of the identified heavy metals in any specific herbal supplement, but is rather intended to provide guidance for limits in the event any such specifications are set. This guidance is not, in fact, applicable for some herbal supplements. In addition, it may not be relevant to test any specific herbal supplement to determine the level of any or all of the heavy metals identified in this guidance.
• The above quantitative limits are determined at the highest labeled dose of a supplement, and are applicable only to herbal supplements that are consumed in a total daily amount of 5 grams or less.
• A product in compliance with this guidance may require a warning in order to comply with California Proposition 65’s listing of these chemicals.

Current "safe harbor" levels under California Proposition 65

1. The specific chemical listed as a carcinogen is "arsenic (inorganic arsenic compounds)," while that listed as a developmental toxin is "arsenic (inorganic oxides)."
2. Limit for inhaled arsenic is 0.06 µg/day; the level given here is the limit for exposure by other routes, e.g., ingestion, and is identified simply as "arsenic," even though the listed chemical is inorganic arsenic.
3. "Arsenic (inorganic oxides)" is listed in OEHHA’s current (May 2008) "safe harbor" publication as a "second priority" for establishment of a MADL. A "draft oral MADL" of 0.1 µg/day for "arsenic (inorganic oxides)" was identified by OEHHA in 2003.
4. The carcinogen listing is for "cadmium and cadmium compounds," while "cadmium" is listed as a male developmental toxin.
5. The number given here for cadmium is for inhalation; no level is given for oral consumption and cadmium is not generally considered carcinogenic by the oral route; the listing of cadmium in the Proposition 65 list does not, however, state this clearly.
6. "Lead" is listed as a developmental toxin. "Lead and lead compounds," as well as "lead acetate," "lead phosphate" and "lead subacetate" are listed as carcinogens.
7. This is the oral level given for lead as a carcinogen. Separate (and higher) levels are identified for lead acetate (23 µg/day), lead phosphate (58), and lead subacetate (41).
8. The carcinogen listing is for "methylmercury compounds." Listings as developmental toxins include "mercury and mercury compounds" and "methyl mercury."
9. "Methylmercury compounds" is recorded as a "third priority" for establishment of an NSRL as of May 2008.
10. Both "mercury and mercury compounds" and "methyl mercury" are currently (May 2008) listed as "second priorities for development of MADLs. A "draft MADL" of 0.3 µg/day for methyl mercury was identified by OEHHA in 1994.

Heavy metal limits for Canada’s Natural Health Products

* Health Canada is reportedly considering establishment of a limit of 0.03 µg inorganic arsenic/kg bw. See Kyeyune V and Marles R. May 20, 2008. Organic and inorganic arsenic in Natural Health Products; Issue Analysis Summary (IAS). See PDF. Accessed on December 23, 2008.

JECFA (and EU as indicated) heavy metal limits

U.S. Agencies: Current quantitative heavy metal limits