CBD and heavy metals

by Tom Russell August 18, 2020

CBD and heavy metals

When heavy metals such as lead, zinc and arsenic are present in the soil, they can accumulate in plants. This is particularly true of the hemp used in CBD production. If the correct steps are not taken during farming and manufacturing, unsafe levels could be present in the extracts used to make CBD products.

Our bodies naturally hold small amounts of these metals, but if they build up too quickly, they can cause severe problems with your heart, brain and other vital organs. Most CBD products are perfectly safe to consume but it is best to understand the risks and how to minimise them when choosing your product.

What are heavy metals

Heavy metals in soilHeavy metals are metals made up of particles that are packed tightly together. They are poisonous, even in small amounts. Those most often found in soil are:

1. Mercury
2. Lead
3. Chromium
4. Arsenic
5. Cadmium
6. Copper
7. Zinc
8. Nickel

A US study revealed that the most common contaminants in a sample of CBD products were lead, arsenic, cadmium and mercury.

Heavy metals are a particular concern in farming and the production of food or food supplements like CBD, because they accumulate in soil and are absorbed into crops. These substances are naturally present in the soil, but contamination can occur to top them up to unsafe levels.

Contamination of soil occurs in many ways, including from industrial emissions, metal waste, fertilisers, manure, sewage, pesticides and wastewater. If farmers identify that the soil in an area is contaminated, they must treat it to remove the metals before they can use it again.

Hemp is a bioaccumulator 

Hemp plantWhile heavy metal contamination is a widespread problem, CBD products are particularly at risk because hemp is a bioaccumulator. This means that it automatically absorbs heavy metals from the soil allowing them to build up in its leaves and flowers.

Their roots can extend up to 8 feet into the ground, meaning that even traces of contaminants are collected from a large amount of soil and concentrated into the plant tissues. When manufacturers extract the CBD from the hemp, the metals can become further concentrated, resulting in unsafe levels in the final product.

What are the dangers caused by heavy metals?

Human BodyHeavy metals become toxic when they reach a specific concentration in your blood. Your body can only get rid of a small amount at a time, so if you continue to be exposed to them, they can build up to be unsafe, even from relatively small amounts.

The danger posed by contaminated CBD is most likely to be chronic conditions caused by the build-up of small amounts over time. The first effects include headaches, tiredness, weakness, aches and constipation. The long-term effects of heavy metal poisoning depend on which metals substances you've been exposed to but can include heart abnormalities, memory loss, anaemia, kidney damage or liver damage.

Lab testing is essential to avoid contaminated products

How to Read CBD Lab ReportsResponsible CBD brands take several steps to ensure that their products are safe and free from heavy metals. As customers, the best way to find out if a product is contaminant free is to look for the third-party lab results. These are detailed tests conducted with samples of each batch of a product by an independent lab.

Currently, some labs don't routinely test for heavy metal contamination, but it's becoming more common. For example, CannabiGold include a screening for heavy metals alongside a profile of the cannabinoids. When companies include heavy metal screening in their lab tests, it's a good indication that they've taken the correct steps to produce a safe, contaminant-free product.

Choosing organically certified products

soil association and EU Bio stampsAnother useful way to avoid contaminants is to opt for those with an official organic certification. Organic products are grown using natural methods, including crop rotation and natural fertilisers. Because heavy metals can accumulate in food chains and be present in animal manure, some organic products are just as likely to be contaminated with heavy metals.

However, at for the Ageless, our method is to prioritise products with certification from organic authorities with rigorous standards. These organisations conduct extensive checks and implement safety checks for fertilisers and other items.

For example, the UK Soil Association and their EU equivalent require the use of approved fertilisers only. These can only be accepted when they have safe levels of heavy metals and they consider them as suitable for use. These organisations also use inspections and soil testing to ensure that their members continue to meet rigorous safety standards.


The global level of heavy metal contamination continues to become rarer as standards in farming and industry increase. Still, hemp as a bioaccumulator could pose a risk to your health if a low-quality product is consumed. Choosing them from trusted manufacturers who use third-party labs to screen for contaminants or those who've met organic standards is a great way to ensure that you only buy safe products.

for the Ageless banner

Tom Russell
Tom Russell


Tom Russell writes extensively about CBD oil and other groundbreaking food supplements. He and his wife share their home with two daughters and a lifetime’s collection of books.

Leave a comment

Comments will be approved before showing up.

Also in CBD blog

CBC – What is this cannabinoid?
CBC – What is this cannabinoid?

by Laura Howarth June 10, 2024


by Tom Russell May 14, 2024

CBD strengths explained
CBD strengths explained

by Laura Howarth May 06, 2024