Aquaculture Contributes a Higher Proportion to Children's Daily Intake of Polycyclic Aromatic Hydrocarbons Than to That of Adults in Eastern China

Submerged plant-biochar composite system exhibits effective control over residual organic pollutants in the benthic organisms of aquaculture ponds

As of now, submerged plants and biochar have demonstrated significant benefits in aquaculture pond sediment remediation. However, there is limited research on the synergistic effects of biochar and submerged plants in mitigating hydrophobic organic contaminant (HOC) accumulation in aquaculture benthic organisms and in controlling the nutrient (nitrogen and phosphorus) levels in aquaculture water. This study assesses a submerged plant-biochar system's efficacy in removing HOCs from simulated freshwater aquaculture ponds. Vallisneria natans was planted in sediment with varying levels of wheat straw biochar, while Corbicula fluminea served as the targeted benthic organism. The bioaccumulation experiment identified the optimal biochar ratio for the Vallisneria natans-biochar system in controlling HOCs in aquaculture products. Analyses included final accumulation concentrations in benthic organisms, changes in freely-dissolved concentrations in aquaculture sediment, and a mass balance calculation to explore key factors in their removal from the system. Results indicated that the Vallisneria natans-1.5% biochar composite system achieved optimal control of HOCs in sediment and aquaculture products. Biochar addition to the sediment in the composite system demonstrated a "promotion with low addition, inhibition with high addition" effect on Vallisneria natans growth. Notably, the addition of 1.5% biochar (VN1.5 group) significantly promoted the growth of Vallisneria natans leaves and roots. Comparing the final pollutant proportions in different environmental media, concentrations in water (0.20%-1.8%), clam accumulation (0.032%-0.11%), and plant absorption (0.10%-0.44%) constituted a minimal portion of the overall pollutant load in the system. The majority of pollutants (24%-65%) were degraded in the aquaculture environment, with microbial degradation likely playing a predominant role. Bacterial phyla, particularly Proteobacteria and Firmicutes, were identified as potential direct contributors to pollutant degradation in the Vallisneria natans-biochar system.

Association of occupational exposure to polycyclic aromatic hydrocarbons in workers with hypertension from a northeastern Chinese petrochemical industrial area

Elevated urinary polycyclic aromatic hydrocarbon metabolites have been linked to an increased risk of cardiovascular diseases (CVDs). However, for petrochemical workers with potentially high PAH exposure, it remains largely unknown whether the link will be amplified. Thus, this work aimed to investigate 14 urinary mono-hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in 746 petrochemical workers working in a Chinese petrochemical industrial area and their association with the risk of hypertension using the binary logistic regression. Metabolites of naphthalene, fluorene, phenanthrene, and pyrene were frequently detected in the 746 urine samples analyzed (>98%), with Σ₁₀OH-PAH concentration in the range of 0.906-358 ng/mL. 2-hydroxynaphthalene accounted for the largest proportion of ten detected OH-PAHs (60.8% of Σ₁₀OH-PAHs). There were significant correlations between these metabolites and other factors, including gender, age, and body mass index. Diastolic blood pressure, not systolic blood pressure, was significant positively associated with the urinary Σ₁₀OH-PAH concentrations of the petrochemical workers. Elevated urinary 2/3-OH-Flu was significantly associated with an increased risk of hypertension (adjusted odds ratio: 1.96, 95% confidence interval: 1.20-3.18, p = 0.007), suggesting that PAH exposure in petrochemical workers was a driving factor of hypertension. In the stratified analysis, the association was more pronounced in those who were overweight with older age. Although the PAH exposure risk in petrochemical workers based on the estimated daily intakes was relatively low. Given the long-term impact, we call attention to CVDs of petrochemical workers.

An application of waste algae biochar in aquaculture water to remove co-existed cadmium and PAHs and the corresponding mechanism

Water quality in aquaculture farms is highly related to the quality of aquaculture products and the connected environment. Cadmium (Cd²⁺) and polycyclic aromatic hydrocarbons (PAHs) are two of the most common pollutants in the aquaculture water, while biochar derived from waste algae (Enteromorpha prolifera), namely BE, was applied in farms ponds to improve water quality. Firstly, the adverse environmental impact of BE was minor, while the concentrations of the heavy metal (Cd²⁺ in the present study) and PAHs (FLU, PHE, FLT and PYR) were removed with efficiencies of 49%, 88%, 90%, 91% and 88%, respectively. The ecological risk values (RQs) were reduced subsequently with a rate of 58 ± 11%. After dosing BE, the ecological risk values in all the studied ponds were lower than 1, indicating no ecological risk in the corresponding aquaculture environment. The sorption capacities (q_m) of BE were 15, 12, 6.3, 0.41, 0.29 and 0.56 mg·g^-1 for Cd²⁺, FLU, PHE, FLT, PYR and BaP, respectively. The sorption capacities were acceptable compared with those derived from other types of biomass. The removal mechanisms were partition (PAHs), complexation (Cd²⁺), π-π interaction (Cd²⁺ and PAHs), precipitation (Cd²⁺) and ion-exchange (Cd²⁺). Practically and theoretically, the algae biochar is applicable in the aquaculture environment, where Cd²⁺ and PAHs co-exist.

In-situ biochar amendment mitigates dietary risks of heavy metals and PAHs in aquaculture products

Heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) are two common contaminant groups of concern in aquaculture products. While biochar amendment can be one of the solutions to immobilize these contaminant in pond sediment, its in situ effectiveness in mitigating the bioavailability, tissue residue, and dietary risk of these contaminants is yet to be tested. In this study, we added wheat straw biochar in sediments of three aquaculture ponds with polyculture of fish and shrimps and employed passive sampling techniques (i.e., diffusive gradient in thin film for HMs and polydimethylsiloxane for PAHs) to assess the diffusion flux and bioavailability throughout the culturing cycle. Reduction in HM concentrations in organisms by biochar after 28 weeks ranged from 17% to 65% for benthic organisms and from 6.0% to 47% for fish. ΣTHQs values of HMs dropped from 2.5 to 2.1 and 1.2 to 0.91 for the two organisms with the initial ΣTHQs value above 1.0. The decrease rates of both the concentrations and ΣTHQs values followed the order of Cu > Cr > Pb > Cd, which was closely correlated with the speciation of HMs in the sediments. ΣPAHs values dropped significantly at the growth stage (20^th week) and the mature stage (28^th week), and, on average, by 34% across all the organisms. Carcinogenic PAHs in aquaculture products decreased dramatically at the seedling stage (12^th week), while there was no significant change observed for the Incremental Lifetime Cancer Risk values. By comparing the freely-dissolved concentrations in pore water of sediments and the overlying water, consistently enhanced diffusion fluxes of HMs and PAHs from water to sediment over the whole culturing cycle were obtained. Our results demonstrated the in situ applicability of biochar amendment to remediating chemical pollution in aquaculture environment and safeguarding quality of aquatic products.

Occurrence of polycyclic aromatic hydrocarbons (PAHs) in the seafood from an important fishing area in the East China Sea and a comparison between seafood from different origins

Polycyclic aromatic hydrocarbons (PAHs) were analyzed in a variety of coastal marine seafood from the Wentai fishing area, which is in proximity to highly urbanized areas and provides a significant portion of the marine aquatic products in Eastern China. Specifically, total PAHs ranged from 320 to 2500 ng/g d.w., whereas carcinogenic PAHs ranged from 21 to 92 ng/g d.w. According to the source diagnosis, the PAHs in the seafood were generally from sources highly related to fossil fuel. Thus, it is necessary to control the unintentional use of fossil fuels and optimize the energy structure in the terrestrial area nearby. Moreover, the food chain structure and the environmental behavior of PAHs through the food chain, which are relevant to dietary risk, were assessed. The δ¹⁵N values fell in a narrow range, which indicates a relatively short food chain, which is due to overfishing in this area. Furthermore, in this shortened food chain, the trophic magnification factors (TMFs) ranged from 0.23 to 6.6, which were generally higher than those in more complex food chains. The cancer risk (ILCR) ranged from 2.2 × 10^-8 to 2.2 × 10^-6. It is noted that the carcinogenic risk of consuming yellow croaker, which is one of the most popular seafood among people on the east coast of China, was the highest. In conclusion, trophic magnification implied a possible elevated risk through this marine food chain, and overfishing may have increased the uncertainty associated with TMF estimations.

Variability in urinary biomarkers of human exposure to polycyclic aromatic hydrocarbons and its association with oxidative stress

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants. Urinary concentrations of mono-hydroxylated metabolites of PAHs (OH-PAHs) have been used as biomarkers of these chemicals' exposure in humans. Little is known, however, with regard to intra- and inter-individual variability in OH-PAH concentrations and their association with oxidative stress. We conducted a longitudinal study of measurement of urinary concentrations of 15 OH-PAHs and 7 oxidative stress biomarkers (OSBs) of DNA damage [8-hydroxy-2'-deoxyguanosine (8-OHdG)], lipid [malondialdehyde (MDA) and F₂-isoprostanes (PGF_2α)] and protein [o,o'-dityrosine (diY)] peroxidation in 19 individuals for 44 consecutive days. Metabolites of naphthalene (OHNap), fluorene (OHFlu), phenanthrene (OHPhe), and pyrene (OHPyr) were found in >70% of 515 urine samples analyzed, at sum concentrations (∑OH-PAH) measured in the range of 0.46-60 ng/mL. After adjusting for creatinine, OHNap and ∑OH-PAH concentrations exhibited moderate predictability, with intra-class correlation coefficients (ICCs) ranging from 0.359 to 0.760. However, ICC values were low (0.001-0.494) for OHFlu, OHPhe, and OHPyr, which suggested poor predictability for these PAH metabolites. Linear mixed-effects analysis revealed that an unit increase in ∑OH-PAH concentration corresponded to 4.5%, 5.3%, 20%, and 21% increase in respective urinary 8-OHdG, MDA, PGF_2α, and diY concentrations, suggesting an association with oxidative damage to DNA, lipids, and proteins. The daily intakes of PAHs, calculated from urinary concentrations of OH-PAHs, were 10- to 100-fold below the current reference doses. This study provides valuable information to design sampling strategies in biomonitoring studies and in assigning exposure classifications of PAHs in epidemiologic studies.

Occurrence of polycyclic aromatic hydrocarbons in fried and grilled fish from Shandong China and health risk assessment

Diet is the main way for the human body to ingest polycyclic aromatic hydrocarbons (PAHs). In this study, the occurrence, dietary exposure, and health risks of 15 PAHs in 31 fried and grilled fish samples were investigated, which were collected from the Shandong Province of China. The results showed that benzo[a]pyrene (BaP) of 5 samples exceeded the European Union (EU) limit value. Naphthalene (NaP) and fluorene (Fle) were present in all samples, and the average concentration of ∑15PAHs was 91.1 μg/kg, with light PAHs dominated. The average contamination level of ∑15PAHs in fried and grilled fish was distributed differently, and there seemed to be more PAH contamination in the grilled samples. The results of the margin of exposure (MOE) suggested that PAH ingestion through fried and grilled fish did not imply significant toxicological concern for consumers in Shandong. The incremental lifetime cancer risk (ILCR) values for the consumption of fried and grilled fish were higher than 1 × 10-6, indicating a potential health risk in the adult population. The study provides baseline health information on PAH intake by residents due to dietary exposure to fried and grilled fish food products, suggesting that health risk monitoring of PAHs in such foods should be continually performed.

Applicability of Equilibrium Sampling in Informing Tissue Residues and Dietary Risks of Legacy and Current-Use Organic Chemicals in Aquaculture

Equilibrium sampling based on silicone polydimethylsiloxane (PDMS) has been used to determine the concentrations of freely dissolved hydrophobic organic compounds (HOCs) and assess the thermodynamic potentials for bioaccumulation of these compounds in the aquatic environment. This allows the use of PDMS-based sampling techniques in assisting conventional sampling and extraction methods for the determination of the concentrations of HOCs in aquaculture products. The present study is an ex situ demonstration of how well PDMS can inform the tissue residues and dietary risks of legacy or current-use organic chemicals in aquaculture species from farm ponds in eastern China. For legacy contaminants such as polybrominated diphenyl ethers (PBDEs, n = 10), good agreement between the predicted concentrations based on PDMS and the measured lipid-normalized concentrations was observed for 60% of the studied biota, including both pelagic and benthic species. For pesticides currently used, such as pyrethroid (PE) (n = 4) and organophosphate pesticides (OPPs, n = 7), the measured tissue residues were consistently higher than those predicted by PDMS, possibly caused by the continuous input from the surroundings. For the organochlorine pesticides (OCPs, n = 5), the only detected chemical was also underestimated. Adjusted by ingestion rates of aquaculture products and toxicology data, the target hazard quotients of these chemicals predicted from PDMS were generally comparable to those derived from measured concentrations in tissue because of the predominance of PBDEs. Overall, PDMS-based equilibrium sampling offered an alternative approach for the prediction of tissue residues and dietary risks of PBDEs. Moreover, it should be applied with caution for PEs, OPPs, and OCPs. Improving the application of PDMS for these chemicals in farm ponds warrants future study. Environ Toxicol Chem 2021;40:79-87. © 2020 SETAC.

Contribution of aquatic products consumption to total human exposure to PAHs in Eastern China: The source matters

Demand for aquatic products surges, due to the increasing concerns on high-quality nutrition and food security. Eastern China is the leading area in contributing significantly to both production and consumption of aquatic products from inland aquaculture, coastal fishing, and distant-water fishing. It is imperative to comprehensively assess the dietary risks of common chemical hazards, such as polycyclic aromatic hydrocarbons (PAHs) in aquatic products of these supply origins, and the contribution of aquatic product consumption to total human exposure. The observed body loads of total PAHs in the coastal aquatic products varied significantly, indicating an unstable food quality from the east coast of China. In the meantime, benzo[a]pyrene equivalent concentrations (BaP_eq) exhibited the highest level in the aquatic products from inland farm ponds. High BaP_eq, along with high consumption of inland aquaculture products, led to higher corresponding cumulative carcinogenic risks (ILCRs) than the other two kinds of products, which further indicate that the origins and consumption rates of the aquatic products do matter. Furthermore, it is confirmed that the consumption of aquatic products is an important contributor to the total daily exposure to PAHs, especially for children and pregnant women. Finally, it is necessary to apply practical remediation in aquaculture farm ponds to provide high-quality products, especially for the population groups of children and pregnant women, and alleviate the exposure and risk due to the PAHs in aquatic products.

Magnetic activated carbon (MAC) mitigates contaminant bioavailability in farm pond sediment and dietary risks in aquaculture products

Heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) are among the contaminants of concern in aquaculture ponds due to their frequent detection and high bioaccumulation in aquatic products and hence high dietary risks to human beings. In this study, magnetic activated carbon (MAC) was added as a stabilization and removal adsorbent to native pond sediment with known contamination of HMs and PAHs to reduce the tissue residues and dietary risks of HMs and PAHs in a model aquaculture species (Venerupis philippinarum) in the course of a 28-day bioaccumulation experiment. Meanwhile, passive sampling techniques based on diffusive gradient in thin films (DGT) and polydimethylsiloxane (PDMS) were applied to sense the bioavailable fraction of HMs and PAHs in sediment during the stabilization process. The results showed that 3% dosage of MAC to sediment achieved the most cost-effective stabilization for HMs and PAHs. A remarkable decrease was observed with the tissue residues of HMs and PAHs in V. philippinarum (28-47% for HMs and ~76% for ∑PAHs), which was quantitatively linked to the decline in their bioavailable concentrations in sediment pore water (31-46% for HMs and ~76% for ∑PAHs). Consequently, the target hazard quotients (THQs) posed by HMs and incremental lifetime cancer risks (ILCRs) by PAHs in V. philippinarum were reduced by 38% and 46%, respectively. Along with the magnetic recovery of ~70% MAC from the sediment, HMs (4.8-13%) and PAHs (2-60%) can be effectively removed. We further established a multi-domain equilibrium sorption model that was able to predict the optimal amendment of MAC for quantitative mitigation of bioavailable PAHs in sediment pore water within a certain range of MAC dosage. Future studies are warranted to explore the applicability domain of MAC for in situ remediation in aquaculture ponds to ensure the quality of farming organisms or to serve other purposes in aquatic systems.