Plant growth regulator residues and dietary risk assessment of table grapes and strawberries in Shanghai

The objective of this study was to get a clear picture of the residue levels of plant growth regulators (PGRs) on table grapes and strawberries in Shanghai, and provide scientific basis for their production and consumption safety. Residues of twenty PGRs were investigated in 152 batches of table grapes and 91 batches of strawberries produced in Shanghai from 2018 to 2019. The dietary risks of chronic exposure and acute exposure of PGRs in table grapes and strawberries were assessed for different population groups. Investigation results showed that gibberellic acid (GA₃) and forchlorfenuron (CPPU) were commonly applied before and after blooming on table grapes, while no PGRs were used during the whole growth period of strawberries. The residue detection results showed that four PGRs residues were detected in grapes, including abscisic acid (ABA), GA₃, chlormequat chloride (CCC) and indoleacetic-3-acid (IAA), among which ABA showed the highest detection rate of 100% and the mean concentration was 0.088 mg/kg. The detection rates of the rest three PGRs were below 6.0% in table grapes. ABA and IAA were detected in strawberries, among which ABA showed the highest detection rate of 100% and the mean concentration was 0.886 mg/kg. The dietary risk assessments showed that the maximum long-term exposure risk (%ADI) of four PGRs from Shanghai’s table grapes and strawberries through diet was 0.004%, which was far below 100% and indicated negligible dietary intake risk. The acute exposure risks expressed as %ARfD of CCC by table grapes consumption was 0.55%, which was also far lower than 100% showing that the acute intake risk was acceptable. In general, the residues and dietary exposure risks of PGRs from table grapes and strawberries in Shanghai were all at the relatively low level.