Pesticide Load: how FairGrow weighs the impact of every spray
Not every litre of crop protection weighs the same. Pesticide Load puts a number on what a product does to people, to wildlife and to soil and water, so you can compare sprays on more than dose alone.
Three questions for every active substance
Pesticide Load (PL) asks three questions about every active substance in a product. How harmful is the product to the person who sprays it? How toxic is the substance to birds, bees, fish, earthworms and water plants? And how does it behave in the environment: does it break down quickly, does it build up in fish, does it reach groundwater?
Each answer becomes a load of its own: the health load (HL), the ecotoxicity load (TL) and the fate load (FL). Added together they form the Pesticide Load. FairGrow always shows the three parts separately as well, because a high number means something different when it comes from bees than when it comes from groundwater.
Every property is measured against a reference substance
The Danish method compares each property with a reference value: the value of the substance that, when the method was set up in 2007, carried the highest approved load. A substance that is ten times less toxic to fish than that reference gets a tenth of the fish score.
That score is then multiplied by a weight. Short-term effects on fish and water fleas weigh 30, on bees 100, on algae and water plants 3. Persistence in soil and bioaccumulation weigh 2.5, leaching to groundwater 20. These weights are set in Danish law, not by FairGrow.
From one substance to the load on your field
A product often contains more than one active substance. FairGrow multiplies the load of each substance by its concentration in the product, adds up the substances and adds the health load of the product label. That gives the load per kilogram or litre of product.
Multiply that by the dose you sprayed per hectare and you have the load of one application. Add up all applications on a field in one season and you have the Pesticide Load per hectare for that field. FairGrow calculates this automatically for every spray you record in crop registration.
Why the Danish method
Denmark has used Pesticide Load since 2013 as the basis of its pesticide tax: the higher the load, the higher the tax. The method is described scientifically by Kudsk, Jørgensen and Ørum (2018, Land Use Policy 70:384-393) and laid down in Danish law. Every reference value, weight and health score FairGrow uses comes from that law (LBK no. 595 of 29 April 2020, Annex 1).
We chose it because it is public, has been in use for more than ten years and is reproducible: anyone can recalculate our numbers with the same rules. FairGrow follows the Danish rules down to the exceptions, including the one for products authorised only for closed greenhouses. For those, the ecotoxicity and fate loads are set to zero, because the product does not reach the field environment; the health load for the person spraying stays.
Where the numbers come from
The properties of each substance come from the European Food Safety Authority (EFSA): from its peer-review conclusions and from its OpenFoodTox database. We do not use commercial databases. Every value is read twice, independently, and every number is traced back to the page of the EFSA document it came from. Where two readings differed, the original table decided.
Health scores come from the hazard statements (H-phrases) on the product label, as listed in the national product register. Source: EFSA.
An example season
Three sprays on one field: a fungicide, an insecticide and a second fungicide. Calculated with the products as they are in the register.
| Product | Dose | Ecotoxicity | Fate | Environmental load |
|---|---|---|---|---|
| Switch | 1.0 kg/ha | 0.25 | 0.67 | 0.93 |
| Tracer | 0.2 L/ha | 6.41 | 0.02 | 6.44 |
| Luna Privilege | 0.75 L/ha | 0.04 | 1.62 | 1.67 |
| Season, environmental part | 6.71 | 2.32 | 9.03 |
The insecticide weighs most here, mainly because of its effect on bees and water organisms. The second fungicide scores mainly on fate, because its active substance stays in the soil for a long time. Health loads come on top of these figures.
Honest about what is missing
For some substances EFSA has not published a conclusion yet, or a study was not required. FairGrow never fills a gap with zero. A missing property simply does not count, and the result carries the label incomplete, so you can see that the true load may be higher.
Where EFSA only states a limit, for example that a bee dose above 100 micrograms did no harm, FairGrow calculates with that limit. That slightly overestimates the load, which is the cautious side.
What is Pesticide Load?
A number that expresses how much a crop protection product burdens human health, wildlife and the environment per kilogram or litre, according to the Danish method. Per hectare it is the product load multiplied by the dose.
Is a lower Pesticide Load always better?
For the environment and the person spraying, yes. But compare products that do the same job: a product that needs three sprays can end up higher over the season than a heavier product used once.
Why does FairGrow show three parts?
Because they point to different risks. A high ecotoxicity load calls for care with bees and water; a high fate load for care with soil and groundwater; a high health load for protective equipment.
What does incomplete mean?
At least one property of a substance in the product is missing from the EFSA data. That property does not count, so the real load may be higher than shown.
Which substances are covered?
We started with the 59 substances used most in Dutch horticulture. 57 of them now have a load. Boscalid and deltamethrin follow as soon as EFSA publishes its conclusion.
See the load of your own sprays
Record your sprays in crop registration and FairGrow calculates the Pesticide Load per field and per season.
Open crop registration