Polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticide residues in selected marine fish species along the coast of South Africa

[摘要] ENGLISH ABSTRACT: Fish consumption is being threatened by the accumulation of hazardous substances within the flesh due to natural occurrences and anthropogenic activities. This tends to undermine the health benefits derived from fish consumption. Human exposure to hazardous compounds has been predominantly through dietary intake and fish in particular. In this study, global priority contaminants, polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) were assessed in some marine fish species of commercial and local consumption importance. The study aims were to assess the occurrences, levels and profiles of selected organic contaminants in marine species covering low trophic (resident) fish species (blacktail and hottentot); middle trophic species (yellowtail and snoek) and the high trophic (predatory) species (tuna and sharks). Also by using diagnostic ratios, the pollution input sources/history was determined and the locations and species with increased burdens, identified. Screened fish were considered safe for consumption based on comparison with regulatory critical values. Extraction of target compounds (analytes) were efficiently carried out following the quick, easy, cheap, efficient, rugged and safe (QuEChERS) method and analysed simultaneously with gas chromatography coupled to mass spectrometry triple quadrupole (GC-MS/MS). Quality control measures were in place and reference material analysed for method validation. Limit of detection, quantitation and percentage recoveries of analytes were within acceptable values. All the analysed species showed evidence of contamination but with variations in profiles and levels. The profile trend was predominantly low molecular weight (LMW) (i.e. non-carcinogenic) PAHs, however, from Port Elizabeth and Dassen Island high molecular weight (HMW) PAHs predominated. PAHs contamination levels in this study ranged from low contamination (<100 μg/kg) in samples from Hout Bay (87.29 ± 1.96 μg/kg wet weight (ww) in hottentot) to a moderate contamination (<1000 μg/kg ww) in tuna dark muscle from False Bay (636.31± 36.03 μg/kg ww). The PAHs acceptable/presence indicator, benzo(a)pyrene was found in excess of the European Union (EU) maximum limit (2 μg/kg ww) in fish from 8 locations with highest (29.79 ± 0.81 μg/kg ww) in Blue Shark (False Bay). Intra and inter species variations were observed and considered to be due to fish size, lipid content, feeding habit, trophic level and locational input sources. The hottentot and soupfin shark species were not found with measurable levels of benzo(a)pyrene and could be considered acceptable species for human consumption so as to minimize exposure to carcinogenic PAHs. However, the highest DDT level (760.50 ± 484.53 μg/kg ww) was recorded in hottentot (Dassen Island) but was below the Food and Drug Administration (FDA) action level (5000 μg/kg ww). A holistic risk assessment study that will evaluate fish health benefits (nutrients) against the risks (contaminants), plus the effect of heat (cooking methods) on measured contaminants in studied species is recommended for future study.

[发布机构] Stellenbosch University