Plant Protection Products

Health risk assessment of the plant growth regulator Bonzi


Report no: 2013: 30

Published: 03.07.2013

Main message:

In a risk assessment requested by the Norwegian Food Safety Authority, The Norwegian Scientific Committee for Food Safety (VKM) concludes that paclobutrazol, the active ingredient in the plant growth regulator Bonzi, may have teratogenic properties considered relevant for humans.

New plant growth regulator

Bonzi is a new plant growth regulator containing the active ingredient paclobutrazol, intended for use in ornamental plants in nurseries and greenhouses.

Risk assessment

This assessment is based on recognized international methodology and documentation from a large number of experimental studies. The documentation is in part submitted by the pesticide notifier, supplemented by peer reviewed literature.

The conclusions in the assessment will be used by the Norwegian Food Safety Authority when considering the application for registration of Bonzi in Norway. VKM was asked to evaluate possible risk potential related to the properties of Bonzi.


VKM concludes that observations from studies in experimental animals suggest a potential for direct teratogenic effects of paclobutrazol, the active substance in Bonzi.

Furthermore, VKM is of the opinion that the data are inconclusive regarding the sporadically observed incidences of cleft palate in the developmental toxicity studies.


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The Norwegian Scientific Committee for Food and Environment

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