In 1987, I was introduced to hashish. I can still picture it vividly: the smoky attic room, three idiots, and a bong. I turned 18 that day and invited my friends over for a party. For about ten years, I used cannabis in various forms: weed, hashish, polm, and hash oil. We consumed it in various ways: smoking it in a “joint” with tobacco, pure, in a wooden or metal pipe, a bong, or in a space cake. There were many varieties of weed and hashish easily available in Rotterdam coffee shops (specialized in cannabis) and from a few local “distributors.” All sorts of tall tales circulated about where it came from and how it was grown and processed. It seemed simple: “Maroc” came from Morocco and “Afghan” from Afghanistan. But how it was made, and especially what it contained, was a big question mark.
Weed, also called cannabis or marijuana, is potentially the purest product. You can grow it yourself, even in a small flowerpot on your windowsill. No fertilizers, no pesticides. But that doesn’t apply to the stuff you can buy on the street, in cafes and coffeeshops. It’s really worth taking a moment to consider this.
Hash and weed are essentially made of pure cannabis material. Yet, they can become contaminated during production, transport, or storage. During cultivation, the soil can be contaminated with who knows what. Weed grows almost anywhere, so why not on this heavily contaminated piece of land, a grower might wonder. There’s no control or traceability whatsoever.
Pesticides and fungicides are then used, which concentrate in the final product. During processing, impurities such as plastic, grease, and sand can be introduced. Fillers are often used to soften hash, give it a sweet aroma, and increase its weight. If you’re unlucky, you might find that hash or weed is simply contaminated with junk, which can be extremely unhealthy.
Harmful substances and health
The pesticides and fillers found in hash can be significantly more dangerous than residues in food: there are no limits on the pesticides used, as cultivation is illegal and there are no controls whatsoever. As a result, pesticide concentrations in cannabis can be tens to hundreds of times higher than permitted in food. Furthermore, the pesticides concentrate in the trichomes – the very substance at the heart of the matter.
Combustion and inhalation significantly increase the risk: combustion converts many harmful substances into even more toxic ones. When eating, a substance first passes through your stomach and liver (first-pass metabolism), partially breaking down many toxins before entering the bloodstream. Smoking or vaping transfers pesticides and fillers directly into the bloodstream through the lungs, accelerating and increasing the toxic impact.
- Cutting agents: Hash can contain oil, paraffin, sugar, plastic, sand, or sheep fat. Cannabis can also sometimes contain undesirable substances, such as glass, dehumidifiers, or adhesives. The risk of this is moderate, with consequences ranging from mild to severe.
- Pesticides and fungicides: Chemical pesticides are often used in commercial cultivation. These can lead to cumulative damage to organs and the nervous system. The risk of this is high, with insidious harmful effects.
- Heavy metals:Heavy metals can enter the product through contaminated soil and fertilizers. They are neurotoxic and accumulate in the body, potentially leading to serious consequences with prolonged use. The risk is low to moderate.
- Mold and bacteria are particularly prevalent in cannabis due to damp conditions. These can cause lung infections, especially in people with weakened immune systems. The risk is moderate, with effects ranging from mild to severe.
- Residual solvents: Extracts, in particular, may contain residual ethanol, butane, or other solvents. These can be toxic if inhaled, especially at high doses. The risk is low to moderate, usually with mild effects.
Check for yourself
- You can ask about the origin and production method. But because the entire production and supply chain is not regulated, not monitored, and illegal it’s unlikely the information provided is reliable.
- Avoid products that smell chemical, sharp, or plasticky. Pure hash has a uniform color and isn’t too sticky. Hash that is easily malleable and feels sticky, or has a greasy or sweet odor, likely contains added fats. Highly glossy hash is also not good.
- Pure weed is green, with trichomes (tiny crystals), and no sand or foreign particles. Pure hash is evenly colored and not overly sticky.
- The scent is spicy and vegetal without any sharp chemical notes, such as a tar or plastic smell.
- Burn test: Pure products burn evenly and without sparks or drips. The smoke is light in color; black smoke indicates added fats.
- Test: Rub a little burnt weed or hash and if it feels gritty, there might be something in it like sand or glass.
- Solvent extraction and smell test: Dissolve a small amount of hashish in pure ethanol or isopropyl alcohol. Let it evaporate slowly in a clean glass dish. It should leave only a sticky resin residue, and any residue with a sharp, chemical, or “medicinal” odor is suspect.
- Commercial pesticide test strips: There are test strips for organophosphates and carbamates (used in agriculture), among others. Examples: AgraStrip, Quick Pesticide Test (online approx. €25–40 for single tests). These usually work by testing a solution of the sample for enzyme inhibition.
Get it tested
- Eurofins Belgium is
a commercial laboratory offering analyses for cannabinoids, pesticides, heavy metals, and residues. Prices start at approximately €150 per test.
Website: https://www.eurofins.be - University and research institutes:
Sometimes universities (e.g., KU Leuven, ULB) offer analyses within research projects. This is not directly accessible to private individuals. - Jellinek DIMS (Netherlands)
Anonymous drug testing service, including cannabis. Often free or for a small fee (€10–€20). Sometimes accessible for people in border regions such as Brussels.
Website: https://www.jellinek.nl/onderzoek/dims/ - Temporary testing campaigns.
Sometimes there are testing campaigns at festivals or events in the Netherlands and Belgium. However, this is not a permanent feature.
Homegrown, possesion and the law
We can conclude that there’s a fair amount of fraud going on with hash and weed. As a user, you clearly run potentially serious health risks. Lab tests are the only way to test cannabis of uncertain origin and production methods for harmful substances. However, growing it yourself is the only way to be sure your weed is pure, free of pesticides and additives. Therefore, if you can’t resist smoking weed or hash, it’s the safest option to take the cultivation into your own hands. And that also carries a risk. In the Netherlands and Belgium, you’re not allowed to possess or grow cannabis. If anything is found on you, it will be confiscated, but you won’t be prosecuted unless there are aggravating circumstances such as drunk driving, indicators of sale like bags, or proximity to a school. In Belgium , you can carry up to 3 grams of cannabis and have one female plant at home. In the Netherlands , it’s 5 grams and 5 plants.
Sources and links
- Trimbos Institute – Information about drugs and drug testing: https://www.trimbos.nl/
- Jellinek – Information about cannabis: https://www.jellinek.nl/
- VAD – Flemish Expertise Centre for Alcohol and Other Drugs : https://www.vad.be/
- Safe ‘n Sound – Drug testing in Brussels: https://www.safeandsound.brussels/
- Modus Vivendi – Drug checking services in Belgium: https://www.modusvivendi-be.org/
- What does (Belgian) law say about cannabis? https://www.druglijn.be/drugs/cannabis/wet
- Cannabis laws and regulations in the Netherlands https://www.informatiecentrumcannabis.nl/wet-en-regelgeving/wet-en-regelgeving-rondom-cannabis/
Disclaimer – This article is for general informational purposes only and does not constitute legal advice. Laws and regulations may change, and their application may vary depending on the circumstances and interpretation by the police, judiciary, and judges. For personal legal advice, it is recommended that you contact a lawyer or a specialized agency. The author of this information accepts no liability for actions taken based on this content.
