To be able to ensure environmental safety, we first need to understand what the potential risks are. Do you actually know what the difference between a hazard and risk is?
A shark in the water is a strong hazard. But if standing safely ashore, there is so exposure to the hazard – as a result, there is no risk. If standing in the water, you're directly exposed to the hazard – accordingly, there is a risk.
So, what does that mean in the context of environmental safety?
To understand the potential risk and effect of using a specific crop protection product, we need to understand the intrinsic hazard of a substance for a wide range of organisms – and we need to know what the potential exposure levels in the environment could be.
Effect Level Testing
Toxicity to different species is tested.
Birds & Mammals
Acute (mortality) and chronic (reproduction) effects on birds and mammals from exposure to residues in feed items.
Effects on survival and reproduction for arthropods like beetles, spiders and mites – both in the field and in field margins.
Acute and chronic effects on earthworms, soil macro-organisms (e.g. soil mites) and micro-organisms (bacteria).
Acute and chronic effects on all levels of aquatic food chain/web – algae, plants, invertebrates and fish.
Mortality of individuals after oral and contact exposure for honeybees and - if required - other bee species.
Effects on seeds and young plants outside of the cropped field.
Exposure Level Testing
Environmental fate and modeling are used to investigate and describe the behavior and distribution of substances in different environmental compartments.
Using the results from effect and exposure levels testing, we can describe the environmental risk.
To get all this information, we evaluate and test in several areas.
The science of ecotoxicology has evolved over the past 50 years and — as indicated by the name — combines knowledge and techniques from both ecology and toxicology.
How toxic is the compound to the non-target organisms?
Testing on mites, beetles, parasitic wasps and sometimes spiders. Measured toxicity values are LR50 and ER50. Usually, the product is tested.
Testing on different plant species representative for different taxonomic groups, including monocotyledonous and dicotyledonous plant species (e.g. beet, sunflower, tomato, ryegrass etc.). Usually, the product is tested.
Testing on earthworms, soil mites, springtails and soil microorganisms. Usually, the active substance, the product and also major metabolites are tested.
Acute and chronic testing on adult honeybees and if needed, additional testing on bumblebees and honeybee larvae.
Testing for effects of acute and chronic exposure to a substance on mice, rats and/or rabbits. Many tests on rats, mice, etc. are conducted to investigate and describe the effects of a substance in humans (human toxicity). Some of these results are also useful for understanding potential effects on wild mammals and the data relevant to the area of ecotoxicology. As a result, we can reuse the toxicity data for ecotoxicology questions – this means that we only test vertebrates once, instead of running two separate tests.
Testing for the effects of both acute and chronic exposure to a substance on fish, aquatic invertebrates (e.g. water fleas), sediment organisms, algae and aquatic plants. Usually, the active substance, the product and also relevant metabolites in water and/or sediment are tested.
Testing for effects of acute and chronic exposure to a substance on quails, mallards and sometimes canaries.
Testing the impact of a crop protection product on non-target organisms is very important, as one of our key goals is to protect the organisms that are not targeted by the crop protection product.
To be able to investigate the exposure of all the organisms we do not want to harm, we need to understand what happens to a substance when it is released in the environment.
Degradation in soil (both aerobic & anaerobic) and on soil surface via sunlight: how long does it take until a substance is degraded in soil, and which metabolites are formed in which amounts? Studies are conducted in the laboratory under standardized conditions, as well as in the field to test more realistic conditions. This information is used to generate the degradation half-life of a substance and a degradation pathway in soil. Adsorption and desorption studies describe the binding of a compound to the soil. These studies are conducted in the laboratory under standardized conditions to determine the immobility or mobility of a compound in the environment.
Volatility describes the evaporation of a substance in the air. The degradation of a substance in the air is calculated with an agreed model that simulates chemical reactions of the substance with hydroxyl radicals and ozone produced by sunlight. A compound with a half-life shorter than 2 days is not prone to spreading in the air over long distances.
How likely is it that an active substance and its relevant metabolites can reach groundwater, and which concentrations can be expected? We answer this question by simulating the mobility and transport of the compounds in soil with agreed scientific models. In the EU, different soil and weather conditions representative for agricultural areas all over Europe is evaluated. Besides these soil and weather scenarios, information on the application regime, application rate, application timing, number of applications and the crop to which a product will be applied, as well as information on the degradation and adsorptions in the soil are considered. The predicted concentrations of a pesticidal active substance in groundwater (at 1m depth under a treated plantation as a worst-case) must be lower than 0.1 μg/L, otherwise, the use of the product is not allowed in the EU.
Degradation and distribution in surface water bodies: how long does it take until a substance is degraded in surface water, and which metabolites are formed in which amounts – both in water and in the sediment? This information is used to generate the degradation or dissipation half-lives of a substance and a degradation pathway in water-sediment systems. The impact of sunlight and of run-off and drainage from treated fields are investigated as well.
Based on our research on the environmental fate, the properties of the compound and the use pattern, we can predict the concentrations in the different environmental compartments.
Using exposure models agreed by regulatory authorities and national calculation schemes, we can deduct a PEC (Predicted Environmental Concentration) value.
Expected concentrations of the active substance and its metabolites in water after exposure via drift, drainage and run-off.
- Exposure via drainage
- Exposure via drift
- Exposure via run-off
- Exposure via leaching into groundwater
Environmental Safety Assessment
Based on the knowledge about ecotoxicology, environmental fate, and environmental exposure, we conduct an environmental safety assessment:
Do the expected concentrations in the environment pose a non-acceptable risk to non-target organisms?
By comparing information about exposure levels causing effects and concentrations in the environment, a conclusion about potential risk is reached. Assessment and calculation schemes vary all over the world – but these basic principles are the same. So, let’s have a look at Europe as an example – what happens in a basic risk assessment?
The "toxicity-exposure-ratio" indicates the environmental safety margin.
An evaluation is conducted for birds and mammals. The expected exposure is estimated via expected residue levels in feed items. To evaluate acute effects (i.e. mortality risk) from acute intake of a substance, this exposure is compared to the LD50 (the Lethal Dose at which 50% of the tested animals died) determined in bird or mammal studies. For potential effects from chronic exposure, the NOEL (No Observable Effect Level) from long-term studies is used for comparison. The consumed residues are evaluated according to feeding habits (e.g. insectivore, herbivore, omnivore, granivorous, frugivorous) of what are known as (generic) focal species. Species and diet composition vary according to the crop and growth stage. A safety margin is built-in, and the risk is considered acceptable when the expected exposure is 10% of the LD50 (= safety margin of 10) and 20% (= safety margin of 5) of the NOEC (No Observed Effect Concentration) for birds and mammals.
An evaluation is conducted for earthworms, soil macro-organisms (e.g. soil mites) and micro-organisms (bacteria). In Europe, for example, the predicted concentrations in soil after application of a plant protection product are compared to the long-term (NOEC) exposure levels in ecotoxicological tests to assess the environmental safety of the uses. Concentrations in soil are estimated and evaluated for the time directly after application of a product and, if required, accumulated exposure after multiple years of use. To increase the margin of safety, an assessment factor of 5 is considered (exposure must stay below 20% of theNOEC).
An evaluation is conducted for all areas represented in the aquatic food web: Algae, aquatic plants (e.g. Lemna), aquatic invertebrates (e.g. water fleas), sediment organisms and fish. It is checked whether the predicted concentrations in water and sediment are acceptable when compared to the concentrations in ecotoxicological tests. To evaluate acute effects (i.e. mortality risk) from acute exposure to a substance, this concentration is compared to the LC50(the Lethal Concentration at which 50% of the tested animals died) concentrations in acute studies. For potential effects from chronic exposure, theNOECorEC50from long-term studies is used for comparison. A safety margin is built in – concentrations of 1% of theLC50(= safety margin of 100) for acute risk assessment, and 10% of theNOECorEC50(= safety margin of 10) for chronic risk assessment, are considered acceptable. The concentrations in water and sediment are estimated for situations where the water is directly next to the field. If these concentrations show a potential risk, mitigation measures are mandatory to reduce the exposure (e.g. no-spray buffer zones, where the farmer has to keep a specified distance from the nearest body of water when applying a pesticide or use specific equipment that reduces the drift). You can learn more about mitigation further down in the scroll-story.
An evaluation is conducted for honey bees and also for non-Apis bees if required. It is assessed whether the estimated exposure after application (both oral and contact) can be considered safe when compared to the levels in ecotoxicological tests. The risk is acceptable when agreed pre-defined trigger values are met, or when evidence from tests performed under more realistic exposure conditions shows that the specific use would not pose a risk to bees.
An evaluation is conducted for effects on survival and reproduction for arthropods inside and outside of the treated field. The exposure levels from either direct overspray (in the field) or spray-drift (outside of the field) are compared to the rates tested in ecotoxicological tests for their effects on mortality(LR50)and reproduction(ER50)The risk is considered acceptable if the effects in the field are below 50% or the potential for recovery is demonstrated. For the off-field risk, additional assessment factors are considered.
An evaluation is conducted regarding effects on seeds and young plants (looking at emergence of seedlings, growth, plant weight, signs of phytotoxicity, etc.) for a range of plant species. The exposure levels expected from spray-drift from the field are compared to the relevant effect levels (e.g. the lowest ER50) derived from ecotoxicological tests. The safety assessment includes a built-in safety margin (e.g. safety margin of 5). If needed, a no-spray in-field buffer zone is to be respected by the farmer to protect non-target terrestrial plants outside of the cropped field.
Using the results from our research, we devise measures to control (eliminate or reduce) an unintended impact of our products on the environment. The appropriateness of such measures is evaluated by the authorities during the registration process. These are examples of possible mitigation options:
No-spray and run-off buffer zones to mitigate exposure via drift and/or run-off
No-spray buffer zones
No-spray buffer zones mitigate spray drift. They are spaces between the application area and the environment, acting as an additional safety measure.
A run-off buffer is an area that acts as a cushion between the field that plant protection products were applied to and the nature in the surrounding area. It helps to prevent potential run-off from reaching the environment and non-target organisms.
The spray drift is the potential spread of plant protection products to the environment in the vicinity of the application area. Special nozzles can help reduce this drift to lower the risk.
The instructions on the product label ensure that the product is used in the right amount, at the right time, in the right areas and on the right parts of the crop.
Additionally, it states how the product and the container should be disposed of correctly. Thus, if applied accordingly, the potential impact on the environment and the non-target organisms can be reduced significantly.
International working groups are constantly reviewing the current state of scientific knowledge, technology, and agricultural practice. Based on this, they propose options for risk mitigation and management. You can find examples here:
Is environmental safety necessary to get a registration?
The registration processes for active substances and products ensure that all parts of the environmental risk assessment are evaluated by independent authorities all over the world – in Europe, for example, this is done both at EU and Member State level.
A product is registered and can be sold on the market only if the environmental safety assessment concludes “no unacceptable effects” for all areas, meaning that the product can safely be used.
- Explanation of Hazard and Risk (Bayer)
- Crop Protection in perspective (Bayer)
- The science of bee testing and pesticide risk assessment (Bayer)
- Video: Environmental Safety (English, German, French, Spanish)
- Interesting information about Agriculture (videos, posters, infographics, reports, brochures published by Crop Life America)
Environmental Safety Assessment in the EU