- GB maximum levels for food supplements as sold: lead 3.0 mg/kg, cadmium 1.0 mg/kg, mercury 0.1 mg/kg.[1]
- Thallium has been measured in shilajit supplements at up to 0.5 µg/g, sometimes above the raw material tested.[2]
- About one in five Ayurvedic medicines bought online in a US study contained detectable lead, mercury or arsenic.[3]
- A batch COA covering metals and microbiology is the only practical way for a buyer to check.
Where contamination comes from
- Source rockMetals in the rock bind to the organic material as it forms.
- CollectionSoil, debris and microbes are gathered with the resin.
- ProcessingSlow drying, open trays and equipment can add microbes or foreign matter.
- AdulterationFillers or look-alike materials added to increase weight.
- StorageMoisture and poor packaging allow mould growth.
Contaminant types at a glance
Scroll sideways to see the full table.| Contaminant | Why it matters in shilajit | Usual test | GB supplement limit |
|---|---|---|---|
| Lead | Present in many rock types; accumulates in the body | ICP-MS | 3.0 mg/kg[1] |
| Cadmium | Toxic to kidneys; occurs with zinc-bearing minerals | ICP-MS | 1.0 mg/kg[1] |
| Mercury | Highly toxic even at low levels | ICP-MS or cold-vapour AAS | 0.1 mg/kg[1] |
| Arsenic | Naturally present in some rock; inorganic forms are most toxic | ICP-MS (total arsenic) | Not in the 2008 supplement limits; see benchmarks |
| Thallium | Measured in shilajit and supplements[2] | ICP-MS | Rarely tested on consumer COAs |
| Microbes | Collected and dried outdoors; moisture supports growth | Total viable count, yeasts and moulds, pathogens | See microbiology guide |
| Mycotoxins, pesticides, PAHs, solvents | Possible from storage, surrounding land or processing | LC-MS/MS or GC-MS/MS screens | See benchmarks |
| Adulterants | Fillers and look-alike materials | Identity and adulterant testing | Not a limit question: the product should simply be what the label says |
Limits apply to supplements as sold in Great Britain; Northern Ireland follows EU rules. Other benchmarks are discussed on heavy-metal limits: UK rules and other benchmarks.
Heavy metals in more detail
Metals are the contaminant most specific to shilajit, because they come from the material’s origin rather than from careless handling. Problems with metals in traditional preparations are well documented: a US study of Ayurvedic medicines bought online found about one in five contained detectable lead, mercury or arsenic, and three-quarters of those products claimed to follow Good Manufacturing Practice.[3] That study was not about shilajit specifically, but it shows why a quality claim needs a test result behind it.
For shilajit itself, a 2025 study measured thallium at up to 0.226 µg/g in natural shilajit and up to 0.5 µg/g in commercial supplements, with some supplements higher than the crude samples.[2] Thallium sits outside the standard “big four” metals panel, so most consumer COAs won’t mention it. See heavy metals in shilajit and heavy-metal testing.
Reading a real report: total vs inorganic arsenic
Most consumer reports give total arsenic, which adds together inorganic forms, the more toxic ones, and organic forms. A total figure on its own can’t tell you how much of the toxic fraction is present. A published report for Nature Elixirs batch SJ2509 shows how a careful laboratory presents it:[4]
- Two figures, reproducedThe report gives 0.98 mg/kg in the results table and 0.70 mg/kg in the remarks, with a stated 55% measurement uncertainty. We reproduce both rather than choose one.
- No limit for total arsenicThe report notes no maximum level for this parameter, consistent with GB supplement law.[1]
- Speciation recommendedThe laboratory recommends determining inorganic arsenic, and the brand has stated future testing will include it.
The lesson applies to any product: a total-arsenic figure tells you about all arsenic forms combined, and speciation tells you how much is inorganic. We discuss this report in full in the Nature Elixirs evaluation.
Thinking in exposure, not just pass or fail
A result under the legal limit is a pass, but what you actually take in depends on how much you use and how many products you combine.
Product A contains lead at 1.2 mg/kg and you take 0.5 g a day: 0.6 µg of lead daily. Product B, a capsule blend, contains 0.8 mg/kg and you take 1 g a day: 0.8 µg daily. Both pass the 3.0 mg/kg limit, but together you take in 1.4 µg of lead a day from supplements alone. Long-term users and people combining products should look at the daily total.
Units and conversions are explained on units on lab reports.
Microbial contamination
Shilajit is collected outdoors, often stored before processing and sometimes sun-dried in open trays. Each stage can introduce bacteria, yeasts and moulds. Water extraction followed by controlled drying reduces the risk; minimal processing increases it. A useful COA reports total viable count, yeasts and moulds, and specific pathogens such as E. coli and Salmonella. See microbial contamination and microbiological testing.
What a contaminant panel should include
- Lead, cadmium, mercury and arsenicWith numerical results, units and detection limits.
- MicrobiologyTotal viable count, yeasts and moulds, and named pathogens.
- The finished productTested after processing, not only the raw material.
- Your batchThe batch number matching your jar.
- Optional but usefulThallium, mycotoxins and pesticide screens.
Why this matters for a raw mineral-organic material is covered in why contaminant testing matters. If a product makes you ill or you suspect contamination, see reporting a problem in the UK.
Common questions
Does all shilajit contain heavy metals?
Most natural materials contain traces of metals, and shilajit forms in contact with rock. The question is whether levels are within legal limits and what your daily total is, which only a test can show.
Is there a legal limit for arsenic in supplements?
Arsenic was not among the food-supplement maximum levels added to GB contaminant law in 2008, which cover lead, cadmium and mercury.[1] Labs and brands often apply other benchmarks; see heavy-metal limits.
Can I test my shilajit for metals myself?
Not at home. Food-testing laboratories accept samples; ask for an ICP-MS metals panel and the detection limits. See laboratory testing.
Sources & further reading
Primary research, regulators and standards bodies are cited first. A source being listed here does not mean it supports every claim made by sellers; it supports the specific statement it is attached to.
- European Commission (UK version on legislation.gov.uk). Commission Regulation (EC) No 629/2008 amending Regulation (EC) No 1881/2006 setting maximum levels for certain contaminants in foodstuffs. legislation.gov.uk, 2008. View source (opens in a new tab) [UK legislation (retained)]
- Quantifying of thallium in Shilajit and its supplements to unveil the potential risk of consumption of this popular traditional medicine. BMC Chemistry 19:20, 2025. doi:10.1186/s13065-025-01384-7. View source (opens in a new tab) [Laboratory analysis]
- Saper RB, Phillips RS, Sehgal A, et al.. Lead, mercury, and arsenic in US- and Indian-manufactured Ayurvedic medicines sold via the Internet. JAMA 300(8):915–923, 2008. View source (opens in a new tab) [Cross-sectional product survey]
- AGROLAB LUFA GmbH (published by Nature Elixirs). Test report, Himalayan Shilajit, batch SJ2509, sample 765188. natureelixirs.com, 2025. View source (opens in a new tab) [Brand-published laboratory report]