To evaluate the pollution characteristics of heavy metals in vegetables from Qingpu District, Shanghai and analyze the risk of dietary intake.

A total of 809 vegetable samples from 6 major vegetable categories were continuously collected over 3 years from 2022 to 2024. The content of total arsenic, total mercury, lead and cadmium were determined by microwave digestion and inductively coupled plasma mass spectrometry. The pollution levels were assessed using the single-factor pollution index (P_i) and Nemerow comprehensive pollution index (P_N). The health risks of dietary intake were evaluated using the target hazard quotient(THQ) and total target hazard quotient (TTHQ).

The detection rate of heavy metals in 809 vegetable samples was 80.2%. The detection rates of the 4 kinds of heavy metals ranked in descending order: cadmium>total arsenic>lead>total mercury, their average content were ranked as lead (0.0408 mg/kg)>cadmium (0.0182 mg/kg)>total arsenic (0.0123 mg/kg)>total mercury (0.0013 mg/kg). All samples complied with the limits specified in GB 2762—2022 National food safety standard-Contaminant limits in food, with all P_i<1. The P_N of different vegetable categories was all less than 0.7, and the order was solanaceous vegetables=onion and garlic vegetables>cucurbit vegetables>aquatic vegetables>leafy vegetables>cabbage vegetables. The single heavy metal THQ from high to low was total arsenic>cadmium>lead>total mercury. Overall, the order of TTHQ for different vegetable categories was leafy vegetables>cucurbit vegetables>cabbage vegetables>onion and garlic vegetables>aquatic vegetables>solanaceous vegetables. The TTHQ for both adults and children was less than 1.

The vegetables produced in Qingpu District of Shanghai are not contaminated by total arsenic, total mercury, lead and cadmium, and are at a safe level. There is no significant health risk to the study population from dietary intake of these 4 kinds of heavy metals in vegetables.