Arsenic and arsenic species in cultured oyster (Crassostrea gigas and C. corteziensis) from coastal lagoons of the SE Gulf of California, Mexico

Bioaccumulation of Essential and Potentially Toxic Elements in the Muscle and Liver of the Spotted Ratfish (Hydrolagus colliei) From Deep-Sea Waters off the Northern Gulf of California

This study aimed to establish the distribution of As, Cd, Cu, Pb, and Zn, in the muscle and liver of the spotted ratfish Hydrolagus colliei from the northern Gulf of California to establish the bioaccumulation background data in this species. The individuals (n = 110) were obtained by bycatch from the Gulf of California hake fisheries, and the metals and metalloid were measured by atomic absorption spectrometry. The element with the highest concentration in the muscle (15.19 ± 5.40 mg kg^-1) and the liver (20.98 ± 10.30 mg kg^-1) was As, followed by essential elements (Zn > Cu), and the lowest were the non-essential Pb (0.029 ± 0.014 and 0.048 ± 0.038 mg kg^-1, muscle and liver, respectively) and Cd (0.022 ± 0.014 and 0.796 ± 0.495 mg kg^-1, muscle and liver, respectively). The liver showed higher bioaccumulation than the muscle in all the studied elements. The sex was not a factor that influenced the bioaccumulation. The concentrations of As in the muscle did not exceed the maximum permissible limits of Mexican legislation, and < 50% of the samples exceed Cd and Pb limits of the Mexican, European Union, and WHO/FAO regulations. The differences found between the elements and tissues could be related to the different diets of the species, their migratory patterns, and their life conditions. Studies in the deep-sea water H. colliei are limited, and further investigations are needed regarding the feeding habits of H. colliei as well as the interactions of potentially toxic elements within the deep-sea water habitat.

Human health risk assessment associated with the consumption of mussels (Perna perna) and oysters (Crassostrea rhizophorae) contaminated with metals and arsenic in the estuarine channel of Vitória Bay (ES), Southeast Brazil

The estuarine channel of Vitória Bay was evaluated regarding bioaccumulation of metals (Al, Ba, Mn, Fe, Zn, Cu, Cr, Pb, Ni, Cd, Hg) and As in mollusks. Mussels from an aquaculture farm and transplanted into the estuary, whereas oysters were collected in situ in the same area. Concentrations of Al, Mn, Fe, Cr and As were higher in P. perna, whereas C. rhizophorae bioaccumulated more Ba, Zn and Cu. Arsenic concentrations in P. perna exceeded the limit of the Brazilian legislation in the outer estuary. Salinity seemed to influence metal uptake differently for each bivalve, with P. perna absorbing more metal at higher salinities and C. rhizophorae in areas of lower salinity. Hazard index (HI) >1 revealed risk for both bivalves for high level consumers. Target Cancer Risk (TCR) for As revealed threat for human health associated with the consumption of mussels and oysters from the study area.

Curcumin Has Protective Effect on the Eye Lens Against Arsenic Toxicity

Arsenic is a highly carcinogenic environmental contaminant. Curcumin, the bioactive component of turmeric, exhibits therapeutic efficacy against several chronic inflammatory and infectious diseases. The present study was carried out to investigate the impact of arsenic on eye lens and evaluate the ameliorative potential of curcumin against arsenic toxicity. Gene expression analysis of α, β, and γ-crystallins and fatty acid profile of lens tissues of arsenic-exposed Labeo rohita was examined and the protective effect of curcumin as diet supplement was evaluated. Curcumin-supplemented diet was prepared at 1.5% and 3% and fed to four groups of fish for 7 days prior to arsenic exposure (at 5 ppm and 15 ppm) for 15 days. Gene expression analysis showed downregulation of α and β-crystallins in the eye lens of arsenic-exposed groups (fed basal diet), whereas the groups fed a curcumin-supplemented diet showed insignificant alterations. Similarly, fatty acid fingerprint of lens lipids arsenic-exposed group exhibited reduction in saturated fatty acid and docosahexaenoic acid (DHA) content. However, in 3% curcumin-supplemented diet-fed and arsenic exposed group group, fatty acid profile remained unchanged. Interestingly, concentration of one non-fatty acid, an antioxidant compound (phenol 2,4-bis 1,1 dimethyl; PD) that was identified in the GC-MS fingerprinting through NIST library (version 2.2, 2014), decreased in response to arsenic exposure which was restored to normal level in curcumin-supplemented groups proving the therapeutic potential of curcumin. The findings of the study suggest that curcumin has a protective effect on eye lens against arsenic toxicity.

Arsenic in Tissues and Prey Species of the Scalloped Hammerhead (Sphyrna lewini) from the SE Gulf of California

The bioaccumulation of arsenic (As) in the muscle, liver, kidneys, and brain of the shark Sphyrna lewini was measured in 40 juvenile specimens from southeast Gulf of California. Additionally, the biomagnification factor was calculated through prey items from stomach contents of the analyzed specimens. The concentrations of As (mg kg^-1, wet weight) were higher in the muscle (10.1 ± 0.3) and liver (9.4 ± 0.5) than in the brain (4.5 ± 0.3) and kidneys (4.2 ± 0.2), which may be attributed to the biological functions of each tissue. Positive correlations were found between the levels of As in muscle and liver with the biological parameters of S. lewini. Hammerhead sharks feed mainly of teleost fishes with low As values (Clupeidae fishes, 1.1 ± 0.5; Sciaenidae fishes, 1.0 ± 0.6; Scomber japonicus, 1.2 ± 0.6; and Etropus crossotus 2.1 ± 0.4) compared with the predator, indicating biomagnification. Inorganic arsenic (As_i) in muscle was estimated as 3% of the total As, although muscle consumption is unlikely to represent a risk (HQ < 1) in humans. Moreover, the probabilities of developing cancer were estimated as low (3.99 × 10^-5 to 3.32 × 10^-6). To avoid health risks related to As, a weekly ration must not exceed 69.3 and 484.8 g in children and adults, respectively.

Transfer and bioavailability of inorganic and organic arsenic in sediment-water-biota microcosm

Arsenic (As) contamination in the sediments has received increasing attention, but its transfer and bioavailability to benthic infauna remain much less well known. In the present study, we deployed the diffusive gradients in thin films (DGT) to quantify the different As speciation in the overlying water and porewater, and assessed the exposure pathway, transfer and bioavailability of different As species in an infaunal clam Sinonovacula constricta. We demonstrated a very dynamic transformation and exposure of As in the sediment-water-clam microcosm. In such microcosm, arsenite [As(III)] in the overlying water, pore water and sediments was almost oxidized to arsenate [As(V)]. Conversely, the accumulated As(V) in the clams was reduced to As(III), followed by methylation to dimethylarsinic acid (DMA), whereas the overall conversion of toxic inorganic As species to less-toxic arsenobetaine (AsB) was much poor in the clams. Moreover, biotransformation depended on the As accumulation level. As(III) was the predominant As species in the control and the Low As treatment clam, whereas DMA was the predominant As species in the High As treatment clam. Significant and positive correlations were found between As(V) concentrations in the clams and those in DGT-labile As in overlying water/pore water, as well as between the DMA and As(V) concentrations in the clams and those in the sediment. DMA and As(V) in the sediments was much more bioavailable to the clams than inorganic As [As(III)] and AsB. Moreover, As(III) and As(V) in the overlying water and pore water, as well as DMA and As(V) in the sediments displayed high migration ability. Coupled DGT technology and biotransformation study therefore suggested that metabolism of ingested As species as well as ingestion and retention of DMA resulted in high DMA bioaccumulation in clams.

Arsenic in waters, soils, sediments, and biota from Mexico: An environmental review

We reviewed over 226 studies dealing with arsenic (As) in water bodies (124 sites or regions; 5,834 samples), soils (44; 2,700), sediments (56; 765), rocks (6; 85), mine waste (25; 582), continental plants (17 (77 species); 571), continental animals (10 (32 species); 3,525) and aquatic organisms (27 (100 species) 2,417) in Mexico. In general, higher As concentrations were associated with specific regions in the states of Hidalgo (21 sites), San Luis Potosi (SLP) (19), Baja California Sur (15), Zacatecas (5), and Morelos (4). High As levels have been detected in drinking water in certain locations of Coahuila (up to 435 μg L^-1) and Sonora (up to 1004 μg L^-1); in continental surficial water in Puebla (up to 780 μg L^-1) and Matehuala, SLP (up to 8684 μg L^-1); in groundwater in SLP (up to 16,000 μg L^-1) and Morelia, Michoacán (up to 1506,000 μg L^-1); in soils in Matehuala, SLP (up to 27,945 μg g^-1) and the Xichú mining area, Guanajuato (up to 62,302 μg g^-1); and in sediments in Zimapán, Hidalgo (up to 11,810 μg g^-1) and Matehuala, SLP (up to 28,600 μg g^-1). In contaminated arid and semi-arid areas, the plants P. laevigata and A. farnesiana exhibit the highest As levels. These findings emphasize the human and environmental risks associated with the presence of As in such regions. A synthesis of the available techniques for the removal of As in water and the remediation technologies for As contaminated soils and sediments is given. The As occurrence, origin (geogenic, thermal, mining and anthropogenic) and evolution in specific regions is summarized. Also, the mobilization and mechanisms to explain the As variability in continental environments are concisely given. For future research, a stratified regional sampling is proposed which prioritizes critical sites for waters, soils and sediments, and biota, considering the subpopulation of foods from agriculture, livestock, and seafood. It is concluded that more detailed and comprehensive studies concerning pollution levels, as well as As trends, transfer, speciation, and toxic effects are still required.

Effect of low salinity on acute arsenic toxicity and bioconcentration in shrimp Litopenaeus vannamei juveniles

This study investigated acute arsenic toxicity and bioconcentration capacity in Litopenaeus vannamei because it has been frequently exposed to lower salinities than its isosmotic point (25 g L^-1). Juveniles (9.9 ± 0.4 g) were exposed to low (5-10 g L^-1) and isosmotic salinity (25 g L^-1) levels; As values were 30.8, 20.2, 16.8 and 13.9 mg L^-1 at 5 g L^-1; 30.4, 19.1, 16.8 and 14.8 mg L^-1 at 10 g L^-1; 31.5, 19.0, 15.0 and 11.9 mg L^-1 at 25 g L^-1 at 24, 48, 72 and 96 h LC₅₀, respectively. No significant differences were found among As LC₅₀ values calculated for different salinity levels and same exposure times, concluding that low salinity did not affect shrimp sensitivity to As. Likewise, no significant differences were observed in As bioconcentration in shrimp exposed to the same waterborne As and distinct salinity, supporting the results of acute toxicity. Bioconcentration factors of As maintained a relatively stable tendency where all values (0.8 ± 0.2 to 1.7 ± 0.4) were statistically comparable to 1, indicating that As was accumulated in a similar proportion to waterborne As concentration at three salinity levels. This study proposed 135.3 ± 12.1 μg L^-1 for salinities from 5 to 25 g L^-1 as provisional safe As concentration. According to these results, the hypothesis that sustains an effect of low salinity on As acute toxicity and its bioconcentration capacity cannot be acceptable. Therefore, the information provided allows knowing the threshold levels of As in water to avoid ecological and economic losses.

Arsenic speciation in wild marine organisms and a health risk assessment in a subtropical bay of China

The total arsenic (As) and As species were analyzed in 19 species of wild marine organisms collected from 12 locations in Daya Bay, China; additionally, both the levels of As in the seawater and sediments and the salinity were investigated. The greatest level of As was found in crabs (13.4-35.1 μg/g), followed by shrimps (8.52-27.6 μg/g), benthic fish (3.45-28.6 μg/g), and pelagic fish (1.22-5.23 μg/g). There were significantly positive correlations between the As concentrations in the benthic fish Callionymus richardsonii/shrimp Metapenaeopsis palmensis and those in sediments, indicating that As levels in them were highly dependent on those in the sediments. Arsenobetaine (AsB) (87.3-99.8%) was the most dominant form of As found in all marine organisms. In benthic fish and shrimp, the bioaccumulation of As, especially AsB, was positively correlated with the salinity of the seawater, indicating that the salinity could control the transfer of As. The calculated hazard quotients (HQs) of the inorganic As in the marine organisms were all <1; thus, there was no apparent health hazard through the consumption of wild marine organisms.

Bioaccumulation of trace metals in farmed pacific oysters Crassostrea gigas from SW Gulf of California coast, Mexico

The aim of the study was to evaluate the bioavailability of trace metals (Chromium, Copper, Nickel, Lead, Zinc, Cadmium, Arsenic, and Mercury) in the commercially consumed Crassostrea gigas oysters collected over a 12-month growth period (2011-12) from an experimental cultivation farm in La Pitahaya, Sinaloa State, Mexico. Sediment and water samples were also collected from four different zones adjacent to the cultivation area to identify the concentration patterns of metals. The results revealed that sewage disposals, fertilizers used for agricultural practices and shrimp culture are the major sources for the enrichment of certain toxic metals. The metal concentrations in oysters presented a decreasing order of abundance (all values in mg Kg^-1): Zn (278.91 ± 93.03) > Cu (63.13 ± 31.72) > Cr (22.29 ± 30.23) > Cd (14.54 ± 4.28) > Ni (9.41 ± 11.33) > Pb (2.22 ± 1.33) > As (0.58 ± 0.91) > Hg (0.04 ± 0.06). Bioconcentration Factor (BCF) and Biota Sediment Accumulation Factor (BSAF) exhibited that C. gigas in the region are strong accumulators for Zn and Cd respectively. Thus, the present study proves to fulfill the gap in understanding the rate of bioaccumulation of metals in C. gigas which is regarded as the most sought after oyster species globally.

Prey-specific determination of arsenic bioaccumulation and transformation in a marine benthic fish

The sediments from Chinese coastal waters contain relatively high concentrations of arsenic (As), mainly arsenate As(V), which may be transferred along the marine benthic food chain. The prey-specific determination of As bioaccumulation and transformation in marine benthic fish remains little known. In this study, we focused on a typical marine benthic food chain comprising of sediments, deposit-feeding invertebrates (polychaete Nereis succinea and clam Gafrarium tumidum) and goby fish Mugilogobius chulae. Graded exposed experiments using different As exposure durations and concentrations were conducted to examine their transformation rate and efficiency. Radiotracer techniques were used to determine the rates of As uptake (as arsenate) from seawater, assimilation from two prey and its subsequent efflux in the goby fish. We demonstrated that the two prey (polychates and clams) displayed different As biotransformation in the goby fish. Biotransformation rate was higher in the goby fish fed on the clams than on the polychaetes, and biotransformation efficiency was lower with increasing inorganic As concentration in the prey. The As overall bioaccumulation in the goby fish was very low, mainly because of the low dissolved uptake and dietary assimilation and high efflux. Combining the biotransformation and biokinetics measurements, our findings highlighted that different prey containing different As concentrations and As species resulted in the comparable As bioaccumulation in the goby fish.

Human exposure to organic arsenic species from seafood

Seafood, including finfish, shellfish, and seaweed, is the largest contributor to arsenic (As) exposure in many human populations. In contrast to the predominance of inorganic As in water and many terrestrial foods, As in marine-derived foods is present primarily in the form of organic compounds. To date, human exposure and toxicological assessments have focused on inorganic As, while organic As has generally been considered to be non-toxic. However, the high concentrations of organic As in seafood, as well as the often complex As speciation, can lead to complications in assessing As exposure from diet. In this report, we evaluate the presence and distribution of organic As species in seafood, and combined with consumption data, address the current capabilities and needs for determining human exposure to these compounds. The analytical approaches and shortcomings for assessing these compounds are reviewed, with a focus on the best practices for characterization and quantitation. Metabolic pathways and toxicology of two important classes of organic arsenicals, arsenolipids and arsenosugars, are examined, as well as individual variability in absorption of these compounds. Although determining health outcomes or assessing a need for regulatory policies for organic As exposure is premature, the extensive consumption of seafood globally, along with the preliminary toxicological profiles of these compounds and their confounding effect on assessing exposure to inorganic As, suggests further investigations and process-level studies on organic As are needed to fill the current gaps in knowledge.

Inorganic Arsenic Determination in Food: A Review of Analytical Proposals and Quality Assessment Over the Last Six Years

Here we review recent developments in analytical proposals for the assessment of inorganic arsenic (iAs) content in food products. Interest in the determination of iAs in products for human consumption such as food commodities, wine, and seaweed among others is fueled by the wide recognition of its toxic effects on humans, even at low concentrations. Currently, the need for robust and reliable analytical methods is recognized by various international safety and health agencies, and by organizations in charge of establishing acceptable tolerance levels of iAs in food. This review summarizes the state of the art of analytical methods while highlighting tools for the assessment of quality assessment of the results, such as the production and evaluation of certified reference materials (CRMs) and the availability of specific proficiency testing (PT) programmes. Because the number of studies dedicated to the subject of this review has increased considerably over recent years, the sources consulted and cited here are limited to those from 2010 to the end of 2015.

Comparison of Bioavailability and Biotransformation of Inorganic and Organic Arsenic to Two Marine Fish

Dietary uptake could be the primary route of arsenic (As) bioaccumulation in marine fish, but the bioavailability of inorganic and organic As remains elusive. In this study, we investigated the trophic transfer and bioavailability of As in herbivorous rabbitfish Siganus fuscescens and carnivorous seabass Lateolabrax japonicus. Rabbitfish were fed with one artificial diet or three macroalgae, whereas seabass were fed with one artificial diet, one polychaete, or two bivalves for 28 days. The six spiked fresh prey diets contained different proportions of inorganic As [As(III) and As(V)] and organic As compounds [methylarsenate (MMA), dimethylarsenate (DMA), and arsenobetaine (AsB)], and the spiked artificial diet mainly contained As(III) or As(V). We demonstrated that the trophic transfer factors (TTF) of As in both fish were negatively correlated with the concentrations of inorganic As in the diets, while there was no relationship between TTF and the AsB concentrations in the diets. Positive correlation was observed between the accumulated As concentrations and the AsB concentrations in both fish, suggesting that organic As compounds (AsB) were more trophically available than inorganic As. Furthermore, the biotransformation ability of seabass was higher than that in rabbitfish, which resulted in higher As accumulation in seabass than in rabbitfish. Our study demonstrated that different prey with different inorganic/organic As proportions resulted in diverse bioaccumulation of total As in different marine fish.

Biotransformation and detoxification of inorganic arsenic in Bombay oyster Saccostrea cucullata

Arsenic (As) exists as the toxic inorganic forms in marine water and sediment, while marine oysters usually accumulate high As contents mostly as the less toxic organic forms. It has not yet been clear that how As is biotransformed in marine oysters. This study therefore investigated the biotransformation and detoxification of two inorganic As forms (As(III) and As(V)) in Bombay oyster Saccostrea cucullata after waterborne exposures for 30 days. Seven treatments of dissolved As exposure (clean seawater, 1, 5, 20 mg/L As(III), and 1, 5, 20 mg/L As(V)) were performed. Body As concentration increased significantly after all As exposure treatments except 1mg/L As(V). Total As, As(III), and As(V) concentration were positive correlated with glutathione-S-transferases (GST) activities, suggesting GST might play an important role in the As biotransformation and detoxification process. Organic As species were predominant in control and the low As exposed oysters, whereas a large fraction of As was remained as the inorganic forms in the high As exposed oysters, suggesting As could be biotransformed efficiently in the oysters in clean or light contaminated environment. The results of As speciation demonstrated the As biotransformation in the oysters included As(V) reduction, methylation to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), and subsequent conversion to arsenobetaine (AsB). More As was distributed in the subcellular metallothionein-like proteins fraction (MTLP) functioning sequestration and detoxification in the inorganic As exposed oysters, suggesting it was also a strategy for oysters against As stress. In summary, this study elucidated that marine oysters had high ability to accumulate, biotransform, and detoxify inorganic As.