“We don’t know enough about the risks of exposure to different pesticides together”
How scientists and growers work together to protect crops without health risks for local residents
Fruit and flower bulb growers and local residents work together with scientists towards the same goal: getting clarity on the exposure to pesticides. For both the growers and all local residents. A conversation with researcher Daniel Figueiredo and flower bulb grower Matthé van Lierop.
“The region surrounding Breezand in Noord-Holland is the biggest, contiguous area for the cultivation of flower bulbs in the world”, says Matthé van Lierop. “Think tulips, hyacinths, daffodils, crocuses and lilies.” Van Lierop has been working as a bulb grower since he was twenty years old and is currently chairman of the advocacy group of flower bulb growers in the region Breezand, the KAVB. “We use substances to protect our crops against diseases and pests.”
“There are many different kinds of pesticides, each working in a different way”, explains Figueiredo. “This is why we can’t just say that all pesticides are harmful, we should research the effects and risks of every substance. Biological pesticides are also not automatically less toxic than synthetic ones. Take for example copper sulfate, a natural substance that’s frequently used in organic farming. In certain quantities, it may be harmful. In the end it’s all about the combination of the substance and the quantity: the dose determines the toxicity.”
Thirty years ago, growers used the mindset “there’s no harm in trying” when dealing with plant protection products. But the world is a different place now. “Times have changed”, says Van Lierop. “Nowadays we focus on pushing back the use of plant protection products, especially in recent years. This means we prioritize precision spraying to target diseases with fewer emissions. How often we do this is hard to say. Some crops require us to still spray once a week, depending on the circumstances, but that is by no means true for all crops. And certainly not 52 weeks a year.”
Bulb growers already try to reduce the use of pesticides. What is the reason for this?
“Mainly because of the environmental impact, apart from health”, says Van Lierop. “From 2027 onwards, the ‘Kaderrichtlijn Water’ (Water Framework Directive) will be applied which is designed to improve the quality of ground and surface water. We have been working for years to reduce the emission to surface water by using fewer substances but we do need alternatives to protect our crops. There are still not enough of these.”
Local residents, growers and scientists work together for more clarity on pesticides
Are there any examples for these alternatives?
“We already have a ‘ziek-zoek-robot’ (disease-searching-robot) that drives through the crops autonomously and identifies abnormalities in the plants. Those plants then receive precision sprays. In addition, we’re running an experiment with a ‘laser-weeder’ that locates and kills weeds around the crops with a laser beam.”
Research by Utrecht ľϸӰ and RIVM, to which Figueiredo contributed, shows that the measured exposure to a limited number of pesticides does not pose a direct health risk to local residents. However, researchers did find a link between specific diseases, such as lung diseases and leukemia, and living near fields sprayed with pesticides.
To better understand this, a large follow-up study has been started. This research focuses on measuring the exposure more accurately and linking specific pesticides to disease prevention. The researchers will not only look at the risks of individual products, but also at the effects of combinations of different pesticides.
How exactly does that work?
“We need to better understand what the effects are of combinations of pesticides”, says Figueiredo. “This is not only relevant for bulb cultivation, but for all industries where pesticides are used. More research is urgently needed here.”
“To do this well, accurate registration of pesticides is vital. We need to know which substances were used on which fields and at what moments. Even though farmers already register this, the information is not yet standardized and directly available for research.”
If we want to contribute to a healthier and more sustainable food chain, we need to impose stricter demands on products we import
How far should we go to protect humans according to you as a researcher?
“Our studies are the first step to discover if the exposure of local residents to pesticides could lead to health risks. Measurements show that airborne pesticide concentrations are currently very low - a positive sign. In comparison to the amount of pesticides we ingest through food, the measured concentrations in the air are generally lower.”
“Within the European Union, certain pesticides are banned due to their proven harmful effects on humans, animals and the environment. At the same time we import products from countries where these substances are still being used. This poses health risks not just to consumers, but especially to the people who grow and process these products. This emphasizes the need to not only look at the policies within Europe but also consider our responsibilities as importers and consumers. If we really want to contribute to a healthier and more sustainable food chain, we must be prepared to impose stricter demands on the products we import. Aside from that, we should also provide support to producers in other countries to implement more sustainable alternatives.”
Are growers prepared to cooperate with researchers?
“Definitely”, says Van Lierop confidently. “We are happy with this research. Although, to be honest, some growers were hesitant at first, because what if the substances we use to protect our crops turn out to be harmful? I’d personally like to know. It’s about the health of local residents, which includes ourselves. Moreover, we, the ones who spray these substances, are exposed to the highest concentrations. Actually, the researchers and growers have the same goal: to uncover the dangers and then minimize them. Together with researchers we can look for solutions with the smallest environmental impact while still maximizing the results of our crops. Plant protection products are a huge financial investment as well. The less we need to use them, the better in all respects.”