UCSC’s Professor Capri answers the most frequently asked questions about cadmium in fertilizers.

What is cadmium, and how can humans absorb it?

Cadmium is a toxic chemical element and belongs to the group of heavy metals. Cadmium enters the human body through food, water and air. Some fertilizers contain large amounts of this heavy metal and can increase cadmium concentrations in local soil through fertilizer application. Cadmium can be absorbed by plants through the soil and enter the human body through the food chain.

What is the cadmium-related health risk?

Heavy metals persist long after their release into the soil. If we take cadmium as an example, it does not decompose but moves into the lower layers of the ground and waterways.

The greater the consumption of high cadmium content fertilizers, the more concerning the accumulation of cadmium in the soil. The higher the rate of transfer to crops, the higher the cadmium intake through food.

In the long run, excessive cadmium intake can lead to accumulation in organs, such as the kidneys, and result in diseases related to the toxicological effects of this substance.

The reduction of cadmium in phosphate fertilizers can significantly help to reduce exposure to cadmium and thus reduce the risk to human health.

Furthermore, low cadmium fertilizers help protect the single resource that is the basis of human security, the soil, and can help ensure sustainable and regenerative agriculture.

How can a farmer manage low cadmium in field crops and a consumer minimise cadmium in the diet?

Farmers should use fertilizers with the lowest possible cadmium levels (e.g., below Cd 20mg/kg P2O5). Such action requires comprehensive labels that allow farmers to prevent cadmium contamination of their soil and crops. The European Commission has agreed on a green label for fertilizer products. When the fertilizer product has a cadmium content of less than 20 mg/kg, the statement "Low cadmium (Cd) content" can be added.

The green label directly benefits farmers, who may find it easier to choose products that do not contribute to cadmium accumulation in the soil, and, indirectly, means consumers are buying healthier food.

For consumers, though, it is possible to further minimise the exposure to cadmium in their diet by avoiding certain foods. However, the green label alone can help minimise consumers’ cadmium exposure.

What can we do to address the cadmium issue?

As with many other technologies in agriculture, it is necessary to promote a constant dialogue between all the components of the supply chain: public institutions, the research world, industry, and consumers. Such an exchange can help build a future in which decisions are made based on data and scientific evidence and promote awareness, informed decision making and transparency.

Fertilizer companies must continue to reduce heavy metal contamination, particularly cadmium, and enhance sustainable agriculture.

In addition, supply chain actors may need support and guidance to shift to more sustainable production methods, such as practical assistance and training to raise awareness of soil contamination and promote the use of low-cadmium fertilizers.

I firmly believe that we have an excellent opportunity to transform food systems by contributing to more positive solutions for nature, respecting soil health and fertility, and supporting human health by minimising cadmium content in fertilizers and soils.