study quantified aliphatic and polycyclic aromatic hydrocarbons (PAHs) in Tilapia zillii, a key dietary fish species, to

Overview

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Key numbers

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from 192.96 ± 0.45 to 313.43 ± 0.67 mg/kg, surpassing international maximum residue limits. Benzo(a)pyrene levels in
muscle (20.95 mg/kg) exceeded EU/WHO permissible limits by over four orders of magnitude. Biomarker assays
regulatory limits such as the European Union benchmark of 2 µg/kg for benzo(a)pyrene in fish tissue (9).
Tilapia zillii specimens (n = 60) were collected from the Escravos River (Latitude 5°34′59.99″ N, Longitude
precision and accuracy. Surrogate recoveries within 70–120% were considered acceptable for data validation.
a mass scan range of m/z 50–550. Compound identification was confirmed by matching both retention times and mass
(wet weight), while limits of quantification (LOQ) were calculated as 10× the signal-to-noise ratio.
calibration was verified daily using five-point standard curves ranging from 0.01 to 500 µg/kg, yielding correlation
coefficients (r²) ≥ 0.995. Recovery efficiencies ranged between 82 % and 94 % across tissue matrices. Method detection limits
reproducibility were verified by triplicate analyses of selected samples, with relative standard deviations below 10 %.
Surrogate recovery data within 70–120 % were accepted for quantification. All concentrations were blank-corrected prior to
Where C is concentration (µg/kg), FCR = 36.4 g/day (based on 13.3 kg/year fish consumption), and BW = 60 kg.
RfDs for individual PAHs (e.g., BaP = 0.0003 mg/kg/day) were sourced from USEPA IRIS database. HQ ≥ 1
Where ED = 30 years, AT = 70 years, and CSF for BaP = 0.0073 (mg/kg/day) ⁻¹. Acceptable ECR ranges: 10⁻⁶ to 10⁻⁴.
Monte Carlo Simulation (n = 10,000 iterations) was performed in Oracle Crystal Ball to assess uncertainty in EDI,
95% confidence intervals, mean risk scores and tornado charts to identify dominant input variables influencing cancer risk.
All data were analyzed using SPSS v16. Descriptive statistics (mean ± SE) were computed for each hydrocarbon
Total aliphatic hydrocarbons (TAHs) shown in Table 1 and Figure 2 recorded in Tilapia zillii from the Escravos
kidney to 10388.16 ± 0.98 mg/kg in the gills. A total of 35 C₈–C₄₀ n-alkane components were identified in the tissue samples,
with the nonane (C₉) fraction consistently dominating across tissues, reaching peak values of 2210.80 mg/kg in gills and
1946.70 mg/kg in muscle. The gill exhibited the highest total TAH burden, possibly due to its direct and prolonged exposure
Octane (C₈) was notably undetectable in gills but reached 144.33 ± 0.46 mg/kg in muscle and 78.17 ± 0.03 mg/kg in
kidney, suggesting tissue-selective uptake and metabolism. High C₉ (nonane) values observed (up to 2210.80 mg/kg) may
as hexacosane (C₂₆) and tetratriacontane (C₃₄) was also prominent. C₂₆ reached a peak of 693.02 mg/kg in gills, while C₃₄
concentrations were highest in gills (1230.76 mg/kg) and muscle (797.46 mg/kg), indicating potential for long-term tissue
Figure 2. Total aliphatic hydrocarbon concentration (mg/kg)
Table 1. Concentration (Mean ± SE) of Total Aliphatic Hydrocarbon Components (n-Alkanes, mg/kg) in Organs
River (Table 3 and Figure 3-4). The muscle exhibited the highest total PAH concentration (ΣPAHs = 313.43 ± 0.67 mg/kg),
Anthracene (135.57 ± 0.33 mg/kg) and indeno(1,2,3-cd)pyrene (36.33 ± 0.44 mg/kg) dominated in muscle,
2 µg/kg (wet weight), signifying potential dietary risk. Chronic ingestion of such contaminated fish may induce mutagenic
responses as shown in Table 2. Hepatic CYP1A activity, assessed via ethoxyresorufin-O-deethylase (EROD) induction, was
Table 2. Biomarker Enzyme Activities in Tilapia zillii from Escravos River (Mean ± SD)
2Values represent mean ± standard deviation (n = 6 per group). Statistical significance assessed by one-way ANOVA
Escravos River. Muscle exhibited 313.43 ± 0.67 mg/kg highest PAH burden followed by kidney and liver, while gill
accumulated the highest concentration of total aliphatic hydrocarbons (ΣTAH: 10,388.16 ± 1.52 mg/kg), whereas muscle
tissues retained the greatest total PAH burden (ΣPAHs: 313.43 ± 0.67 mg/kg). The high gill concentration corresponds to
0.88, p < 0.05), suggesting that hydrocarbon metabolism triggers lipid peroxidation and oxidative stress (see Table 2).
and carcinogenic concerns as shown in Table 4. Estimated daily intake (EDI) of benzo(a)pyrene via 20.95 mg/kg dry weight
muscle consumption far exceeds USEPA reference dose of RfD = 0.0003 mg/kg/day resulting in a hazard quotient (HQ) > 1
0.0073 mg/kg/day⁻¹ benzo(a)pyrene yielded values above USEPA threshold of 1 × 10⁻⁴ for both adults and children signifying
Table 4. Estimated Human Health Risk Metrics from PAHs in Tilapia zillii Tissues
0.0073 mg/kg/day⁻¹, TEQ calculated based on BaP equivalents using Nisbet and LaGoy (1992) TEFs.

Methods (brief)

collected across dry and wet seasons, and muscle, liver, kidney, and gill tissues were analyzed using GC-MS in
Study Area and Sample Collection
Tilapia zillii specimens (n = 60) were collected from the Escravos River (Latitude 5°34′59.99″ N, Longitude
Positioning System (GPS) unit. Collected fish were immediately rinsed with site water to remove debris, wrapped in pre-
six hours of capture. Samples were subsequently stored at −20 °C until dissection and analysis. During laboratory processing,
Frozen fish samples were thawed at 4 °C, rinsed with deionized water to remove surface impurities, and dissected
from five individuals per organ per season were pooled to form a composite representative sample, homogenized, and
Ten (10) g (dry-weight equivalent) of each tissue sample was Soxhlet-extracted for 8 h using a 1:1 (v/v) mixture of
concentrated to 1 mL under a gentle stream of high-purity nitrogen. Prior to instrumental analysis, samples were spiked
performance. Procedural blanks and spiked recovery samples were included in each extraction batch to ensure analytical
Chromatography–Mass Spectrometry (GC–MS, Agilent 7890A/5975C MSD). The system was fitted with a DB-5MS fused
curves prepared from standard mixtures of known concentrations. The limits of detection (LOD) ranged from 0.1–0.5 µg/kg
(wet weight), while limits of quantification (LOQ) were calculated as 10× the signal-to-noise ratio.
were calculated as three times the signal-to-noise (S/N) ratio, and LOQs were defined as ten times S/N. Precision and
reproducibility were verified by triplicate analyses of selected samples, with relative standard deviations below 10 %.
kidney to 10388.16 ± 0.98 mg/kg in the gills. A total of 35 C₈–C₄₀ n-alkane components were identified in the tissue samples,
hydrocarbons (ΣPAHs) concentrations in muscle, liver, kidney, and gill tissues of Tilapia zillii collected from the
(HMW) polycyclic aromatic hydrocarbons (PAHs) in muscle, liver, kidney, and gill tissues of Tilapia zillii collected

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised