Antibiotic residues and heavy metals in pork at wet markets in Vietnam

From April 2014 to January 2015, a total of 190 fresh pork samples at
wet markets were collected to produce 18 pooled samples that
represent 18 studied communes in Hung Yen and Nghe An provinces.
Tetracycline, fluoroquinolones, sulfonamide, chloramphenicol groups
were firstly screened by ELISA and positive samples were quantified by
liquid chromatography–mass spectrometry/mass spectrometry (LCMS/MS).
Lead, cadmium and arsenic were determined by Atomic
Absorption Spectrometer (AAS). While pooled samples for tetracycline
and fluoroquinolones (0/18) were negative tested we found positive
test results for sulfonamide (50%, 9/18) and chloramphenicol (16.7%,
3/18). The average residue levels were 155.5 (25.6-263.2) µg/kg for
sulfadimidine, higher than Vietnamese MRL (100 µg/kg) and 0.54 (0.34-
0.76) µg/kg for chloramphenicol, which is prohibited in veterinary
drugs in Vietnam. Regarding heavy metals, there were 5/18 (27.8) of
pooled samples being positive for lead, while cadmium and arsenic
were not detected. The average concentration of lead in pork was 74.1
(70.1-78.7) µg/kg, which was still lower than the standard level applied
for lead in pork (100 µg/kg). There were no significance differences on
the prevalence and concentrations of antibiotic and heavy metal
residues between the two studied provinces. The results highlight the
presence of sulfadimidine and chloramphenicol in pork available at wet
markets. This finding is a component of an ongoing food safety project
(PigRISK), which is assessing the health risks of chemical hazards in
pork and developing incentive-based innovations to improve management
of human and animal health risks in smallholder pig value chains
in Vietnam.