A threshold is an exposure level (dose) along a dose-response continuum below which a defined effect will not occur and above which the probability of an adverse effect occurring increases with increasing levels of exposure (the tipping point). Examples for humans are many, such as the relationship between ineffective and effective doses for pharmaceutical drugs. Similarly, sufficiently large doses of alcohol can lead to acute (intoxication) and chronic (liver disease) effects if abused whereas consumption in moderation or via foods such as fruits, bread and juice do not pose a concern.
Thresholds for adverse effects exist for crop protection products and should be used for risk assessment. Existing test methods also allow for the determination of such thresholds for new products. Strong consensus based on new scientific evidence would be needed before moving away from thresholds for regulatory purposes.
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