Antimicrobial resistance due to potentially toxic metals in fertilising products
Report no: 2017: 28
Potentially toxic metals in soil and fertiliser products can contribute to the development of bacterial resistance to these elements.
This is the key message in a risk assessment conducted by the Scientific Committee for Food Safety (VKM) on behalf of the Norwegian Food Safety Authority.
Potentially toxic metals
In recent years there has been increasing awareness that some metals may have an impact on the development of antimicrobial resistance. The Norwegian Food Safety Authority required an assessment regarding the relationship between antimicrobial resistance and the content of potentially toxic metals in soil and fertiliser products, such as sewage sludge and animal manure.
VKM has considered the following: arsenic, cadmium, chromium, copper, nickel, mercury, lead and zinc. They are assessed because of their possible presence in fertilisers and their potential to induce antimicrobial resistance in different bacterial species.
Lack of data
The assessment is mainly based on internationally published articles.
"There is no systematic monitoring for toxic metals in soils in Norway. Based on available data, we assume that the amount of potentially toxic metals in soil varies in different parts of Norway. The amount depends on past and present agricultural practices and soil conditions," says Yngvild Wasteson, who has led the working group.
Data on potentially toxic metals in fertiliser products transferred to soil is also inadequate. Based on available data, VKM concludes that the use of fertiliser products will increase the amount of potentially toxic metal in soil. In areas of intensive agriculture, the amount will be higher than in areas with lower intensity, according to the report.
"The amount of potentially toxic metals in soil must be assessed from a long-term perspective, because these metals accumulate in the environment," adds Wasteson.
Link to antimicrobial agents
Resistance to potentially toxic metals can be associated to resistance to antimicrobial agents used to prophylaxis and treat infectious disease in humans and animals. There is limited knowledge of the relationship between resistance to potentially toxic metals and coupling to antimicrobial agents.
VKM emphasizes, however, that there are known links between resistance to copper and zinc and antimicrobial agents.
VKM's Panel on Biological hazards is responsible for the assessment.
The Norwegian Scientific Committee for Food and Environment