Heavy-metal limits: UK rules and other benchmarks
In Great Britain, food supplements, including shilajit, must not exceed 3.0 mg/kg of lead, 1.0 mg/kg of cadmium and 0.1 mg/kg of mercury, measured on the product as sold. There is no GB supplement maximum for total arsenic. These are legal limits, not targets: a product well below them is better. Other benchmarks, such as daily-exposure limits used by pharmacopoeias, take a different approach, so always check which basis a report uses.
Lead in Shilajit
Lead can occur in shilajit because it is present in many rocks. Great Britain limits lead in food supplements to 3.0 mg/kg as sold. Lead is harmful in small amounts, particularly to children and during pregnancy, and there is no known safe level of lead exposure. That is why every shilajit batch should be tested for lead, and why shilajit shouldn’t be given to children or taken in pregnancy.
Mercury in Shilajit
Mercury can occur in shilajit at trace levels from the rock it forms in. Great Britain sets the strictest supplement limit for mercury: 0.1 mg/kg as sold, compared with 3.0 mg/kg for lead. Mercury is mainly a concern for the nervous system and kidneys. Some traditional Ayurvedic preparations deliberately include mercury-based ingredients, so it is worth checking that a shilajit product is single-ingredient and tested.
Cadmium in Shilajit
Cadmium is a toxic metal that can occur in shilajit because it is present in some rocks and soils. In Great Britain, food supplements must not exceed 1.0 mg/kg of cadmium as sold. Cadmium matters because the body clears it very slowly, so it accumulates over years, particularly in the kidneys. A batch report should show a cadmium result with units, and long-term daily users should pay particular attention to it.
Heavy metals in Shilajit
Heavy metals can occur in shilajit because it forms in contact with mountain rock and binds the elements in it. The main concerns are lead, cadmium, mercury and arsenic, and research has also found thallium. Levels vary by source and batch, and purification doesn’t reliably remove dissolved metals. Great Britain sets maximum levels for lead, cadmium and mercury in supplements, so a batch-specific laboratory report is the essential check.
Arsenic in Shilajit
Arsenic can occur in shilajit because it forms in contact with rock that contains arsenic. Laboratory reports usually show total arsenic, which combines inorganic arsenic, the more toxic form, with organic forms that are generally considered less harmful. Great Britain has maximum levels for lead, cadmium and mercury in food supplements, but not for total arsenic, so arsenic results need interpretation. Inorganic arsenic testing gives the clearest picture.
Adverse events and case reports
Few adverse events linked specifically to shilajit have been published. Safety reviews report that animal studies have not shown significant toxicity and that the small human trials did not report serious side effects. That is reassuring but limited: trials were small and short, and rare or long-term problems would not show up. The broader risk documented in research comes from contamination, such as metals found in some Ayurvedic products bought online.