Prescreening veterinary drug residues, heavy metal concentration, and genetic authentication in retail catfish fillets in the Northeast United States

Veterinary drug residues, heavy metals, and species authentication were performed on the demand of the regulatory agency in retail catfish fillets. A total of 362 domestic and imported catfish samples collected from various retail markets in the Northeast region of the United States were tested for the presence of chloramphenicol (CAP), malachite green/gentian violet (MG/GV), As, Cd, Pb, and Hg according to the USDA - FSIS protocols. Species identification and mislabeling were also evaluated by DNA barcoding. Results showed 94.2% of samples barcoded successfully and an overall of 11.1% mislabeling was detected. The highest mislabeling rates were estimated for Pangasius bocourti (100%) and Pangasianodon hypophthalmus (16.7%) by species and for Cambodia (45.5%) and Vietnam (19.3%) by country of origin. Eleven samples (0.8%) tested presumptive positive for CAP while MG/GV was detected in 80 samples (22.1%). A total of 49 catfish samples (13.5%) were found to have detectable levels of heavy metals. Cd was found in 44 samples (12.2%) while 4 samples had Pb (1.1%) and only one sample had a detectable level of Hg. The concentration of Pb ranged from 35 mu g kg(-1) to 281 mu g kg(-1) and varied from 10.09 mu g kg(-1) to 395 mu g kg(-1) for Cd. Our results provide basic information about the mislabeling rate and the quality of retail catfish fillets in terms of veterinary drug residues and heavy metal concentration in the Northeastern United States which suggest the necessity of a monitoring program for seafood authenticity and quality.