Abstract
Domoic acid (DA) is a potent neurotoxin that poses public health concerns, especially for children and adolescents during critical neurodevelopmental periods. In the present study, urinary DA concentrations in 216 children and adolescents at the age of 6 to 18 in southern China were determined using a novel dansyl-chloride (DNS-Cl) derivatization high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method with ultrahigh sensitivity (LOQ: 0.087 ng/mL). The median urinary DA concentration was 2.17 ng/mL (interquartile range (IQR): 0.87-4.08 ng/mL). When analyzed by age group, the medians were 1.40 ng/mL (6-9 years; IQR: 0.55-3.49 ng/mL), 2.16 ng/mL (10-13 years; IQR: 0.94-4.07 ng/mL), and 2.93 ng/mL (14-18 years; IQR: 1.06-5.06 ng/mL). Our findings revealed that urinary DA concentrations increased with age and varied significantly across different body mass index groups (p < 0.05), while no significant gender differences were observed. The estimated daily intake (1.73-374 ng/kg/day) remained below established safety thresholds. This study represents the first systematic biomonitoring of urinary DA exposure in children and adolescents from southern China's coastal communities, addressing critical knowledge gaps and establishing baseline data amid rising harmful algal bloom frequency.