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

Rufina-Mary Chinelo, Chukwumalume (2016-03)

Thesis (PhD (Food Sc))--Stellenbosch University, 2016.

Thesis

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.

AFRIKAANSE OPSOMMING: Die verbruik van vis word bedreig deur die akkumulasie van gevaarlike stowwe in die vlees as gevolg van natuurlike oorsake of antropogeniese aktiwiteite. Dit is geneig om die gesondheidsvoordele wat van vis verbruik verkry word te ondermyn. Menslike blootstelling aan gevaarlike stowwe is hoofsaaklik deur inname vanaf die dieet, in die besonder vis. Die universele prioriteitsbesoedelingsagente, polisikliese aromatiese hidrokoolstowwe (PAHs) en organise-chloried plaagdoders, was in hierdie studie in spesifieke mariene visspesies van kommersiële- en plaaslike verbruikersbelang bestudeer. Die doel van die studie was om die voorkoms, vlakke en profiele van gekose organiese besoedelingsagente in mariene spesies, wat die lae trofiese (residensieël) vis spesies (kolstert en hottentot), middel trofiese spesies (geelstert en snoek) asook die hoë trofiese (roofsugtig) spesies (tuna en haai) verteenwoordig, te beoordeel. Diagnostiese verhoudings was gebruik om besoedelings- invoer bronne/geskiedenis te bepaal en om areas en spesies met ‘n verhoogde lading te identifiseer. Gekeurde vis is as veilig vir gebruik beskou gebaseer deur vergelyking met regulatoriese kritiese waardes. Die ekstraksie van teikenkomponente (analiete) was effektief uitgevoer deur die vinnige, maklike, goedkoop, effektiewe, robuste en veilige (QuEChers: quick, easy, cheap, efficient, rugged, safe) metode te volg en was gesamentlik met gas chromatografie verbind met massa spektrometrie driedubbel viervoudig (GC-MS/MS), geanaliseer. Kwaliteitsbeheermaatreëls was opgestel en verwysingsmateriaal geanaliseer vir metode validering. Die limiet van waarneming, kwantifisering en persentasie herwinbaarheid van analiete was binne aanvaarbare vlakke. Al die analiseerde spesies het tekens getoon van kontaminasie, maar met variasie in profiele en vlakke. Die profile tendens was hoofsaaklik lae molekulêre gewig (LMW) (dus nie-karsinogenies) PHAs, alhoewel daar vanaf Port Elizabeth en Dassen Eiland hoë molekulêre gewig (HMW) PAHs voorgekom het. PAHs besoedeling in hierdie studie het gewissel van lae kontaminasie (<100 μg/kg) in monsters vanaf Houtbaai (87.29 ± 1.96 μg/kg nat gewig in hottentot) tot ‘n matige kontaminasie (<1000 μg/kg nat gewig) in tuna donker spier vanaf Valsbaai (636.31± 36.03 μg/kg nat gewig). Die PAHs veiligheidsmerker, benso(a)pireen het die Europese Unie (EU) maksimum limiet (2 μg/kg nat gewig) oorskrei in vis van 8 lokaliteite met die hoogste vlakke (29.79 ± 0.81 μg/kg ww) in Blouhaai vanaf Valsbaai. Intra- en interspesies variasies was waargeneem en was toegeskryf aan visgrootte, lipied inhoud, voedingswyse, trofiese vlak en plaaslike insetbronne. Die lae trofiese vlak species (kolstert en hottentot) het nie meetbare vlakke van benso(a)pireen bevat nie en kan as veiliger species beskou word vir mesnlike gebruik om die blootstelling aan karsinogeniese PHAs te beperk. Die hoogste dichlorodiphenieltrichloroethaan (DDT) vlak (760.50 ± 484.53 μg/kg nat gewig) was egter in hottentot (Dasseneiland) waargeneem, maar was onder die ‘Food and Drug Administration’’ (FDA) optrede vlak (5000 μg/kg nat gewig). ‘n Holistiese risiko assesseringsstudie rondom gesondheidsvoordele van vis (voedingswaarde) teenoor die risiko’s (besoedelingsagente), sowel as die effek van hitte (gaarmaakmetodes) op waargenome besoedelingsagente in die bestudeerde species, word vir toekomstige studie aanbeveel.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/98429
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