The Centre for Food Safety has found excessive pesticide residues in a sample of white string pods from Tsuen Wan Market.
It was found to contain Carbofuran at a level of 0.71ppm.
The centre is still tracing the source of the vegetables.
According to the Pesticide Residues in Food Regulation, the maximum residue limits in string beans for Carbofuran is 0.1ppm.
The centre said the detected levels of pesticide residues would not pose adverse health effects if the beans were consumed in normal amounts.