Pesticides and Microbiology in CBD: What an Independent Laboratory Tests (FAQ)
Find out what an independent laboratory tests in CBD oil: pesticides, heavy metals, mycotoxins, and microbiology. Check how to read the CoA certificate.
The CoA certificate (Certificate of Analysis) is now the standard that distinguishes a reliable manufacturer from a random importer. Meanwhile, a study of 14 CBD oils available on the European market found that 9 of them had cannabinoid concentrations that significantly deviated from the label claims (Pavlovic et al., Molecules, 2018). In practice, this means that two oils described almost identically on the label can differ significantly in actual quality and purity, and the only way to verify this is through an independent laboratory report, not the manufacturer’s declaration. This article specifically explains what an independent laboratory tests, why cannabis is particularly prone to pesticide accumulation, and how to read the certificate before you pay for CBD oil.
KEY INFORMATION
• An independent laboratory tests CBD oil for: cannabinoids, pesticides, heavy metals, mycotoxins, solvent residues, and microbiology.
• Cannabis accumulates compounds from the soil, so cultivation on contaminated fields directly transfers pesticides to the extract.
• A CoA certificate from an accredited laboratory (ISO/IEC 17025) is one of the few reliable proofs of product safety.
• 9 out of 14 tested CBD oils on the European market had cannabinoid concentrations deviating from the label claims (Pavlovic et al., Molecules, 2018).
• Lack of a batch number in the CoA or a certificate from the manufacturer’s internal department are warning signs.
Why are CBD laboratory tests so important?
Industrial hemp (Cannabis sativa L.) is a plant with a unique ability to absorb compounds from the soil: this mechanism is called phytoremediation. Comparative studies of fiber crops conducted in areas heavily contaminated by the metal industry show that cannabis accumulates heavy metals from the soil more effectively than cotton (Angelova et al., Industrial Crops and Products, 2004). The plant absorbs heavy metals from the soil: cadmium, lead, arsenic, mercury, as well as residues of pesticides, herbicides, and fungicides. If the field has been treated with plant protection products in the past, there is a real risk that these compounds will end up in the final extract.
This is not just a theoretical problem. The CBD supplement market has rapidly expanded since 2018, when hemp with low THC content was removed from the list of controlled substances in many EU countries. New manufacturers entered the market with products of varying quality, often without reliable laboratory tests. Therefore, the CoA certificate has become the de facto industry standard for manufacturers concerned about their reputation. Before choosing a specific product, it is worth knowing the full checklist for choosing CBD oil.
What exactly does an independent laboratory test?
A full analysis of CBD oil includes five independent categories of tests. Each of them answers a different question regarding the safety and quality of the product. The table below shows the scope of these tests to help assess whether the certificate presented by the manufacturer is complete.
| Test Category | What it includes | Limits and notes |
|---|---|---|
| Cannabinoid profile | Standard panel: CBD, THC, CBG, CBN, CBC, THCA, and CBDA, with concentration stated in mg or % | The THC threshold for supplements in Poland and the EU is currently 0.3% (sum of delta-9-THC and THCA). A discrepancy greater than ±20% between the label and CoA result is a serious quality issue |
| Pesticides and herbicides | Panel of 200-400 active substances used in plant protection | Regulation (EC) No 396/2005 sets MRL limits; in the absence of a specific limit, the default level is 0.01 mg/kg |
| Heavy metals | Four basic metals: lead (Pb), mercury (Hg), cadmium (Cd), and arsenic (As) | Limits are set by Regulation (EU) 2023/915 and EFSA guidelines. Lead is particularly problematic in industrial soils |
| Mycotoxins | Aflatoxins (B1, B2, G1, G2) and ochratoxin A, toxic fungi from moist biomass | IARC classifies aflatoxin B1 as a group 1 carcinogen. The limit for the sum of aflatoxins in dietary supplements in the EU is 4 μg/kg (Regulation (EU) 2023/915) |
| Extraction solvent residues | ICH Q3C panel for CO2, ethanol, propane, and butane methods | Class 1 (avoid): hexane, pentane, benzene, their presence disqualifies the product. Classes 2 and 3 are limited or acceptable levels |
It is worth knowing that the CoA certificate for pesticides can be issued by two methods: screening, which detects presence above the detection threshold, or quantitative, which provides the exact concentration. A certificate with a quantitative method is more valuable: we know not only “if it is there,” but “how much is there.” Ask the manufacturer what method their laboratory uses. We discuss heavy metals in CBD in more detail, along with detection methods and typical sources of contamination, in a separate article on heavy metals in CBD products. The difference between acidic forms of cannabinoids (THCA, CBDA) and their active counterparts is explained in a separate comparison table.
Why is microbiological testing of CBD performed?
Microbiological testing of CBD oil is a check of the number of viable microorganisms in the product. It is particularly important for individuals with compromised immunity, such as those after chemotherapy, with HIV, after organ transplants, or with chronic autoimmune diseases. For these groups, even a low level of bacterial contamination can have serious health consequences.
The standard microbiological panel includes: total aerobic microbial count (TAMC), total yeast and mold count (TYMC), and tests for the presence of pathogens: Salmonella spp., Escherichia coli, and Staphylococcus aureus. The standards for dietary supplements are included in the European Pharmacopoeia (Ph. Eur.). For TAMC, the limit is usually 10³ CFU/g, for TYMC 10² CFU/g, and for Salmonella and S. aureus, total absence is required.
Where do microbiological contaminants in CBD oils come from? The biomass of cannabis after harvest may contain soil microorganisms. If drying and storing the raw material does not occur under controlled temperature and humidity conditions, molds and yeasts can proliferate. CO2 extraction eliminates most microorganisms because high temperature and pressure are bactericidal, but ethanol extraction at low temperatures may not be sufficient. A good manufacturer tests not only the finished product but also the raw material before extraction.
How to read a CoA certificate step by step?
A CoA certificate may initially appear to be a complicated laboratory document. In practice, it is enough to check a few basic points. Below is a simplified table that helps assess the completeness of the certificate.
| CoA Certificate Element | What to check | Warning signal |
|---|---|---|
| Laboratory name | External, independent from the manufacturer | No name or “internal QC” |
| ISO/IEC 17025 accreditation | PCA or other national authority accreditation number | No accreditation number |
| Batch number (Lot/Batch) | Matches the number on the packaging | No number or mismatch |
| Testing date | Not older than 12 months from the purchase date | Certificate without a date or older than 2 years |
| Cannabinoid profile | CBD, THC, CBG, CBN, stated as numerical values | Only “ND” (non-detected) or no THC |
| Pesticide panel | Min. 100 substances, with limits and results | No panel or less than 50 substances |
| Heavy metals | Pb, Hg, Cd, As, stated as numerical values | No heavy metal testing |
| Microbiological testing | TAMC, TYMC, Salmonella, E. coli | No microbiological testing |
In practice, we see that many manufacturers provide only the cannabinoid profile certificate, without pesticide and heavy metal testing. Such CoA is incomplete information: the buyer sees that “CBD confirmed,” but knows nothing about chemical contaminants. A full certificate should include all four categories: cannabinoids, pesticides, metals, and microbiology. A more detailed discussion of this topic, with additional examples of reading real certificates, can be found in our separate guide on reading the CoA certificate.
Certified vs Conventional Cultivation: How Does It Affect Safety?
A certified organic cultivation certificate (in the EU: the “euro-leaf” logo in accordance with Regulation (EU) 2018/848) prohibits the use of synthetic pesticides and herbicides, significantly reducing the risk of contamination of the final product. However, a certified organic cultivation does not exempt the manufacturer from the obligation to conduct laboratory tests of the finished extract, as the soil may contain historical contaminants from before the period of organic cultivation.
Cannabis certified in the EU must come from varieties registered in the Common Catalogue of Agricultural Plant Varieties, which is maintained by the European Commission based on submissions from member states. The catalogue includes only cannabis varieties eligible for cultivation according to the current THC threshold. Cultivation of unregistered varieties is illegal, and their extract cannot be sold as a dietary supplement on the EU market. Checking whether the manufacturer uses registered varieties is an additional level of quality verification, independent of the CoA certificate itself. In practice, both sources of information complement each other: variety registration speaks to the genetic origin of the plant, while the CoA indicates what actually went into a specific batch of extract, including any soil contaminants described earlier in this article.
Frequently Asked Questions
What does an independent laboratory test in CBD oil?
An independent laboratory tests CBD oil for: cannabinoid profile (CBD, THC, CBG, CBN concentrations), presence of pesticides and herbicides (200-400 substance panel), heavy metals (lead, mercury, cadmium, arsenic), mycotoxins (aflatoxins, ochratoxin A), extraction solvent residues, and microorganism counts. The full results of these tests are included in the CoA certificate, which a reliable manufacturer should publicly provide for each batch of the product.
What pesticides are most commonly detected in CBD products?
Among the plant protection products most frequently mentioned in the context of cannabis contamination are glyphosate, imidacloprid, and carbendazim, especially in the case of low-quality raw material. Cannabis is a so-called phytoremediator: it absorbs compounds from the soil. Certified organic cultivation significantly reduces this risk, but does not eliminate it completely, which is why CoA testing of the final extract is always necessary.
Why do cannabis plants accumulate pesticides more than other plants?
Cannabis has a documented ability to absorb and accumulate compounds from the soil: this mechanism is called phytoremediation, confirmed in comparative studies of fiber plants in areas heavily contaminated with heavy metals (Angelova et al., Industrial Crops and Products, 2004). Plants from fields with historical pesticide residues transfer these compounds to the extract. This is one of the reasons why the quality of the raw material and CoA certificates are so important when choosing CBD oil.
What is a CoA and how to read it?
CoA (Certificate of Analysis) is a report from tests issued by an independent, accredited laboratory. It includes: the name of the laboratory with ISO/IEC 17025 accreditation number, date of testing, product batch number, results for each cannabinoid, and results of pesticide, heavy metal, and microbiology tests. The certificate should be accessible via a QR code on the packaging or on the manufacturer’s website, and the batch number must match the one on your packaging.
What standards apply to pesticides in CBD supplements in Poland?
In Poland and the EU, hemp extract sold as a dietary supplement is subject to Regulation (EC) No 396/2005 on the maximum allowable levels of pesticide residues in food. The default limit for pesticides without a specific MRL is 0.01 mg/kg. Products from accredited laboratories compliant with the ISO/IEC 17025:2017 provide the greatest assurance of compliance with these standards.
Can CBD oils from online stores be dangerous due to contamination?
There is a risk, especially for products without a full CoA certificate. A study of 14 CBD oils available on the European market found that 9 of them had cannabinoid concentrations that significantly deviated from the label claims (Pavlovic et al., Molecules, 2018). Choosing a manufacturer with a full CoA from an external laboratory, a batch number matching the packaging, and a current testing date significantly minimizes this risk.
How to check if a CBD manufacturer really conducts laboratory tests?
Look for a CoA with the name of a specific, external laboratory, not an internal QC department. Check the ISO/IEC 17025 accreditation in the register of the Polish Accreditation Center (PCA). Compare the batch number (Lot/Batch) on the packaging with the number in the CoA: they must be identical. A certificate without a testing date, without a batch number, or issued by a laboratory without accreditation are warning signs that should prevent you from making a purchase.
What is microbiological testing of CBD and why is it performed?
Microbiological testing checks the number of aerobic bacteria (TAMC), yeasts, and molds (TYMC) as well as the presence of pathogens: Salmonella spp., E. coli, and Staphylococcus aureus. Cannabis harvested from fields can accumulate microorganisms from the soil. The standards in the European Pharmacopoeia require TAMC ≤ 10³ CFU/g, TYMC ≤ 10² CFU/g, and absence of Salmonella and S. aureus. This test is particularly important for individuals with compromised immunity.
If you are looking for CBD oil with a full, publicly available CoA certificate, check our offer in the CBD oils category.
This article is for informational and educational purposes. It contains internal links to product categories available in the u Bucha store. Prices and specifications may change: check the current data on the product page before purchasing.
Author: Michał Waluk · Published: 2026-08-09 · Updated: 2026-08-10
