Plant Protection Products

Health risk assessment of the herbicide MCPA (2- methyl -4 - chlorophenoxyacetic acid)


Report no: 2015: 03

Published: 23.01.2015

Key message:

The Norwegian Scientific Committee for Food Safety (VKM) has on request by the Norwegian Food Safety Authority (NFSA) conducted a health risk assessment of the active substance MCPA. VKM concludes that there are no reason to increase the previously determined values for ADI and AOEL. VKM agrees with NFSA in how they have determined the values for dermal uptake.

MCPA (4-chloro-2-methylphenoxyacetic acid) is an active ingredient in several registered herbicides. 

In VKM’s health risk assessment from 2006, the AOEL value was set to 0.036 milligrams per kilogram of body weight based on results from two different experiments in rats. The argument used is that the results from two different rat experiments should be merged. 

NFSA has requested VKM’s Panel for Plant Protection Products for an opinion if it is acceptable to use the manufacturer's approach and increase the AOEL value.

No reason to increase the AOEL value

VKM concludes that it is not acceptable to merge single studies performed several years apart and disregard findings from only one of the studies. VKM does not agree with the manufacturer arguments to raise the AOEL values. 

The manufacturer has also requested a reconsideration of the present values for dermal absorption which was set by NFSA during the administrative review of the product MCPA 750 Liquid in 2013. VKM’s Panel on Plant Protection Products supports the conclusion of NFSA concerning the determination of values for dermal absorption of MCPA. 

VKM’s Panel for Plant Protection Products has conducted the risk assessment. 

The risk assessment was published January 23rd 2015.


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