Occurrence of Antibiotic Residues in Human Milk From Mexican Women With Diverse Health Conditions

Human breast milk is the optimal source of nutrition for infants, yet it may also serve as a pathway for unintended exposure to pharmaceutical contaminants. This study aimed to determine the occurrence of selected antibiotic residues—amoxicillin, erythromycin, chloramphenicol, sulfamethoxazole and trimethoprim—in breast milk samples collected from 23 lactating women in Mexico. Samples were analysed using a validated high‐performance liquid chromatography coupled with tandem mass spectrometry (HPLC–MS/MS) method. Amoxicillin was the most frequently detected compound, present in 14 of 23 samples at concentrations > 10 ng/mL, while sulfamethoxazole and trimethoprim were identified at trace levels (< 10 ng/mL). Chloramphenicol and erythromycin were each detected in a single sample. Although measured concentrations were below therapeutic thresholds, the detection of multiple antibiotics raises concern about cumulative exposure, potential disruption of the infant gut microbiota and antimicrobial resistance. These findings emphasise the need for biomonitoring programmes, strengthened regulations and further toxicological evaluation of antibiotic residues in human milk to ensure infant safety.