Bags of compost and flower bulbs from DIY stores contain dangerous multi-resistant fungi, according to Scientias.nl. Among other things, they harbour the fungus Aspergillus fumigatus, which the WHO classifies as a serious threat to public health.
Summer is in full swing - and that means many people can be found in their gardens again. But watch out with that bag of compost you bought at the hardware store. After all, it may contain more than just soil. "Gardening is a relaxing and enjoyable activity," says researcher Marin Brewer. "But I worry about people not being aware of the health risks that can come with working with compost and bulbs."
Multi-resistant fungi
New research has shown that commercially available compost, soil and flower bulbs contain multi-resistant fungi. And that is quite worrying. "Especially because we found them in such large quantities, without people being aware of the risks," Marin tells Scientias.nl. "Our findings show that there could potentially be tens of thousands of potentially resistant fungal strains in just one bag of compost."
Study
The researchers draw this worrying conclusion after taking samples of various products such as compost, soil, flower bulbs and various foods. These samples were taken between 2019 and 2021 in major retail chains. The team discovered more than 500 strains of the fungus Aspergillus fumigatus in different products, from different brands. Most of the multi-resistant fungal strains were found in soil, manure compost and flower bulbs such as daffodils, dahlias, gladiolus and tulips. "We were relieved to find no multi-resistant strains of Aspergillus fumigatus in purchased foods and nuts," says Marin. "But its high presence in compost and flower bulbs is worrying. People don't associate tulips with anything deadly, but that could be the case."
WHO
That researchers are sounding the alarm is not surprising. A few years ago, the World Health Organisation (WHO) released a catalogue listing the 19 most worrisome fungi that pose a growing and underestimated threat to public health. And one of the fungi listed was Aspergillus fumigatus. The WHO is particularly concerned about resistance, or the fact that this fungus is becoming increasingly resistant to existing drugs. Only a handful of anti-fungal drugs exist, and more and more fungi appear to be less and less impressed by them. So Aspergillus fumigatus is a good example of that. Every year, Aspergillus fumigatus infects more than two million people worldwide. Aspergillosis, the disease caused by this fungus, is a leading cause of death in patients with weakened immune systems. But the fungus also targets people with chronic obstructive pulmonary disease (COPD), cystic fibrosis, type 2 diabetes, HIV/AIDS and even COVID-19. Cancer patients and those on immunosuppressive drugs are also at risk.
More about Aspergillus fumigatus
Aspergillus fumigatus is a ubiquitous fungus. In fact, it is thought that we inhale hundreds of spores of this species every day. Aspergillus fumigatus is found everywhere in the environment and is also found in the nose, throat and pharynx of healthy people. Although this does not always cause noticeable health problems, millions of people fall ill every year. The fungus can cause bronchopulmonary allergic aspergillosis in people with weakened immune systems. Illness symptoms include fever, weakness, chest pain, unexplained weight loss, headache, heart murmur, blood in the urine or abnormal urine colour and straight, narrow lines of broken blood vessels under the nails. Because infection cannot be controlled by existing means, this fungus regularly claims human lives: about eight out of 10 patients with aspergillosis do not survive. Whether Dutch bags of compost also contain the fungus? That cannot be ruled out, according to Marin. "I cannot say with 100 per cent certainty, but it is very likely," she notes.
How?
The question is how exactly this dangerous fungus gets into bags of compost. "This fungus is found in decomposed plant material," Marin explains when asked. "It can withstand heat well and therefore thrives in compost piles. Research has shown that this fungus has become multi-resistant due to the use of fungicides in agriculture that have similar modes of action." And that is bad news. "Strains of Aspergillus fumigatus have been discovered that are resistant to voriconazole, itraconazole and posaconazole," Marin says. "This is an important health concern because these drugs are often used as first choice in the treatment of aspergillosis."
Precautions
Preventing infection with the fungus is particularly challenging. "The fungus is widespread in nature and is found in many places," Marin states. Moreover, you can become infected just by breathing in the spores of the fungus. The researchers therefore strongly recommend that people with weakened immune systems take precautions while gardening and discuss the possible risks with their doctor. Avid gardeners can also wear a mouth mask to give themselves some protection.
The agriculture industry is working to address this issue. In the meantime, Marin has personally stated that she will not plant flower bulbs and will probably not use commercial compost. At the same time, she hopes this study will raise awareness about the potential dangers of multi-resistant pathogens in garden products, so that more people become aware of the risks and can take measures to protect themselves.
Source: Scientias