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Mixture Toxicity

Our position.


Over the years, crop protection products have become increasingly specialized in order to target specific pests and weeds. Farmers also have to guard against resistance, which can occur if the same product is over-used. Therefore, a variety of crop protection products is available to control the same pests, weeds and diseases. As a result, a combination of crop protection products can be present in either the environment or as “multiple residues” in the food. Consumers are concerned about these combinations and want to know what this means for the environment and human health.

We include below some frequently asked questions that you may find interesting as well:

General Questions

"Mixture toxicity" describes the effect that occurs when the toxicity of a combination of different chemicals is higher than the toxicity of each of the individual substances. However, this is not commonly the case.

"Mixture toxicity" occurs when chemicals have a common toxicity. In these cases, toxicity levels can add up or even - in very rare occasions - combine to have a so-called synergistic effect.

Crop protection products can only be approved when a comprehensive set of studies shows that they can be used safely for the farmer, the consumers and the environment.

Regulatory authorities carefully evaluate such studies before they approve a product to be marketed.

As part of the standard pesticide assessment, mixture toxicity is evaluated in our crop protection products that contain more than one active ingredient.



We are all exposed to a wide variety of chemical mixtures in our daily life. Some are man-made; others occur naturally. As a result, the current risk assessment procedure for single substances factors in high safety margins. This cautious approach provides a high degree of confidence that even if the toxicity of different substances adds up, these potential effects are covered. Notwithstanding this, BASF believes that further action is necessary to reduce any potential risk to human health and the environment.

Using existing data from food consumption and residue monitoring programs, authorities and scientists from industry and academia are currently developing a science-based methodology to comprehensively assess the risk of chemical mixtures in the diet.

BASF supports and is actively involved in this important initiative. These efforts are designed to ensure the safety of the human diet and to strengthen consumer trust in food safety.


Any formulations that BASF introduce to the market (including those with more than one active ingredient) are comprehensively tested to ensure their safety for the environment. As a result, potential effects can be assessed in advance so that counter measures can be designed and implemented before a product is registered and marketed. These measures include, for example, the buffer zones placed between fields and the banks of rivers, lakes and streams in order to protect water organisms. Other measures include limiting the application of crop production products to periods outside the plant blooming season and the "flying" season of pollinators.

When a combination of different pesticides occurs, some cases of increased toxicity have been identified that could cause problems for insects, such as bees. These have been addressed by regulatory requirements.

For example, a list of forbidden tank mixtures is included as part of the label instructions.

BASF Position

The effects of combinations of chemicals are referred to as mixture toxicity. This term describes the effect that the toxicity of the combination of chemicals is higher than the toxicity of individual components of the mixture. In fact, we are exposed to mixtures of man-made and natural chemicals every day. Also because of this, current risk assessment procedures for single substances are highly conservative, giving confidence that additive effects are covered in the majority of cases. Even so, BASF is convinced that this topic needs to be taken up to further reduce potential risks.


Therefore, BASF has increased research activities in the area of mixture toxicity and scientifically evaluates the safety of its products regarding combination effects.


BASF currently evaluates mixture toxicity in its products containing more than one active ingredient (e.g. crop protection products) to ensure that they can be used safely for the farmer, the consumer and the environment.


In cases where its products are part of a mixture in the human diet or in the environment (e.g. surface water), BASF works on science-based solutions to evaluate whether these combinations are of (eco)toxicological concern.


Currently, there is no harmonized and internationally-accepted method to assess the risk posed by chemical mixtures to human health and the environment. BASF contributes to scientific solution development together with regulatory bodies, academia and other relevant stakeholder groups.


BASF favors a mixture assessment approach based on available scientific knowledge instead of a general increase of existing safety factors. By this scientific approach, only substances displaying common toxicity shall be evaluated together. To ensure a solid evaluation, BASF believes that all existing data, e.g., from food consumption or residue monitoring programs should be made available.


BASF is committed to identifying and implementing appropriate measures to manage potential risks effectively and maintain high standards of consumer and environmental protection.