The effects of urbanization on small high salinity estuaries of the southeastern United States

Future development in coastal areas of the southeastern United States (US) will likely result from urbanization (housing and tourist/service related activities) rather than industrialization. In an effort to identify potential impacts associated with urbanization, field studies were conducted in two small, high salinity estuaries of coastal South Carolina. The sites selected for study were Murrells Inlet, an estuary with a history of significant urbanization and North Inlet, a relatively pristine, undisturbed estuary. During field studies conducted in the fall of 1990, a series of 96-h in situ bioassays were undertaken at each of the sites. The species used were the grass shrimp, Palaemonetes pugio, and the mummichog, Fundulus heteroclitus. Water samples were collected at the site during these bioassays and analyzed for polyaromatic hydrocarbons (PAH) residues. Adult oysters, Crassostrea virginica, were also deployed at each of the sites during the in situ bioassays and analyzed for tissue PAH residues. Physicochemical water quality and rainfall were also monitored. Mean waterborne PAH levels were significantly higher at the urbanized Murrells Inlet site than at the more pristine North Inlet. Additionally, oysters deployed at the Murrells Inlet site showed increased PAH levels in comparison to baseline values while those deployed at the North Inlet had PAH levels well below baseline concentrations. No siterelated mortality was observed in the two species used in the bioassays. Fluctuations in salinity, dissolved oxygen, and pH were much less extreme at the urbanized Murrells Inlet site than at North Inlet. The less dynamic physicochemical environment at the Murrells Inlet site may be due in part to urban influences (i.e., jetty construction and bulkheading). Additional work is needed to better define the significance of these observations.     

Wood preservative leachates from docks in an estuarine environment

Environmental concentrations and biological effects of certain metals and organic compounds found in wood preservatives were examined. The study focused on leachates from private residential docks in South Carolina tidal creeks. Copper, chromium, arsenic, and polynuclear aromatic hydrocarbons (PAHs) were measured in composite samples of surficial sediments and naturally occurring oyster populations (Crassostrea virginica) from creeks with high densities of docks, and from nearby reference creeks with no docks. In some cases, metal concentrations in sediments and oysters were higher immediately adjacent to dock pilings than they were elsewhere in the same creek. Sediments from most sites had concentrations of metals and total PAHs which were below levels reported to cause biological effects, however. Solid-phase Microtox^® bioassays using whole sediments and rotifer bioassays using sediment pore water showed no significant differences in acute toxicity between creeks with and without docks. Oysters growing directly on dock pilings had significantly higher concentrations of copper than oysters growing at least 10 m away; however, there was no significant difference in the physiological condition of these oysters. Four-day field bioassays measuring percent survival of mummichogs (Fundulus heteroclitus), mud snails (Ilyanassa obsoleta), juvenile red drum (Sciaenops ocellatus), and juvenile white shrimp (Penaeus setiferus) showed no significant differences between sites near to and distant from newly constructed docks. Hatchery-reared oysters showed no significant differences between dock and reference sites in percent survival, growth, or bioaccumulation of metals after six weeks of exposure. The results suggest that, in estuarine environments with a moderate tidal range (1.5–2.0 m), wood preservative leachates from dock pilings have no acutely toxic effects on four common estuarine species, nor do they affect the short-term survival or growth of juvenile oysters.     

Fate and effects of soluble or sediment-bound arsenic in oysters (Crassostrea gigas thun.)

Contaminated sediments are a possible source of stress to the benthic biota. In order to examine this way of transfer concurrently with direct exposure, oysters were exposed to As dissolved in natural seawater or loaded to particles. The sediment used as a vector of transfer was a mud from a coastal area devoted to oyster culture, the finest particles of which have been selected. It was submitted to experimental contamination then to in vitro desorption tests, in which enzymes and pH changes were used to mimic the digestive processes in Molluscs. Although different enzymes or pH induced the desorption of 3 to 24% of sediment-bound arsenic, the accumulation of this element in the soft tissues of oysters remained low after exposure to contaminated particles. The uptake of soluble arsenic was also limited although checking the level of arsenic in seawater every day revealed no significant decrease of the contaminant in the experimental medium. However, cytological effects were noted in oysters exposed to sediment-bound arsenic and moreover to soluble arsenic. They consisted of structural alterations of mitochondria and nuclei, suggesting a disturbance of both the cellular respiratory metabolism and nucleotid incorporation.     

The detection of pollutant impact in marine environments: Condition index, oxidative DNA damage, and their associations with metal bioaccumulation in the Sydney rock oyster Saccostrea commercialis

Specimens of the Sydney rock oyster Saccostrea commercialis were deployed for a 3-month period at control and sewage disturbed marine locations in the Hunter Region, New South Wales, Australia. The DNA damage product, 8-hydroxyguanine, was measured by GC/MS-SIM from chromatin extracts of the gill tissues of oysters to assess oxidative damage. The levels ranged from 11.5 to 18.8 modified bases per 10⁷ guanine bases. Although the condition indices were significantly different between the Redhead control site (178.3±3.6) and the Burwood sewage disturbed location (140.4±4.4), no significant differences in 8-hydroxyguanine concentrations were detected between the sites, and the concentration of 8-hydroxyguanine was not correlated to condition index. However, levels of the DNA base modification were correlated with the concentrations of bioaccumulated lead (r=0.84, P=0.036). This association provides in vivo evidence that the bioaccumulation of lead results in oxidative damage to DNA. An additional control and sewage disturbed site were included to investigate the relationship between heavy metal bioaccumulation and the condition index of deployed oysters. After the 3-month deployment period, the condition index was negatively correlated to concentrations of bioaccumulated mercury (r=–0.80, P<0.001), cobalt (r=–0.65, P<0.01), and nickel (r=–0.69, P<0.01), suggesting a strong negative influence of these metals at relatively low concentrations on the physiological condition of the oysters.     

Trace elements in the Pacific oyster in Hong Kong

The concentrations of six trace elements (arsenic, cadmium, copper, lead, mercury, and zinc) were determined in samples of the Pacific oyster,Crassostrea gigas, taken from a retail market and from a local culture area. Concentrations of arsenic, mercury, and particularly cadmium, were frequently greater in samples purchased at the market than in those taken directly from the field. By contrast, levels of copper, lead, and zinc exhibited only minor differences in oysters from the two sources. The differences in the levels of arsenic, cadmium, and mercury are explained in terms of the marketing procedures; in summer, imported oysters dominate the market, and these oysters are relatively more contaminated by these three elements than are locally culturedC. gigas. The implications with respect to public health are discussed and element levels in oysters are compared to both public health regulations in Hong Kong and to metal concentrations in the same species from elsewhere.     

Evaluation of tropical water sources and mollusks in southern Brazil using microbiological, biochemical, and chemical parameters

Florianópolis, a city located in the Santa Catarina State in southern Brazil, is the national leading producer of bivalve mollusks. The quality of bivalve mollusks is closely related to the sanitary conditions of surrounding waters where they are cultivated. Presently, cultivation areas receive large amounts of effluents derived mainly from treated and non-treated domestic, rural, and urban sewage. This contributes to the contamination of mollusks with trace metals, pesticides, other organic compounds, and human pathogens such as viruses, bacteria, and protozoan. The aim of this study was to perform a thorough diagnosis of the shellfish growing areas in Florianópolis, on the coast of Santa Catarina. The contamination levels of seawater, sediments, and oysters were evaluated for their microbiological, biochemical, and chemical parameters at five sea sites in Florianópolis, namely three regular oyster cultivation areas (Sites 1, 2, and oyster supplier), a polluted site (Site 3), and a heavily polluted site (Site 4). Samples were evaluated at day zero and after 14 days. Seawater and sediment samples were collected just once, at the end of the experiment. Antioxidant defenses, which may occur in contaminated environments in response to the increased production of reactive oxygen species (ROS) by organisms, were analyzed in oysters, as well as organic compounds (in oysters and sediment samples) and microbiological contamination (in oysters and seawater samples). The results showed the presence of the following contaminants: fecal coliforms in seawater samples (four sites), human adenovirus (all sites), human noroviruses GI and GII (two sites), Hepatitis A viruses (one site), JC Polyomavirus in an oyster sample from the oyster supplier, Giardia duodenalis cysts, and Cryptosporidium sp oocysts (one site). Among organochlorine pesticides, only DDT (dichlorodiphenyltrichloroethane) and HCH (hexachlorocyclohexane) were detected in some sediment and oysters samples in very low levels; site 4 had the highest concentrations of total aliphatic hydrocarbons, PAHs, and linear alkylbenzenes (LABs) found either in oysters or in sediment samples. The major concentration of fecal sterol coprostanol was found at site 4, followed by site 3. After 14 days of allocation in the four selected sites, there was a significant difference in the enzymes analyzed at the monitored spots. The detection of different contaminants in oysters, seawater, and sediment samples in the present study shows the impact untreated or inadequately treated effluents have on coastal areas. These results highlight the need for public investment in adequate wastewater treatment and adequate treatment of oysters, ensuring safe areas for shellfish production as well as healthier bivalve mollusks for consumption.     

Unusually high intake and fecal output of cadmium, and fecal output of other trace elements in New Zealand adults consuming dredge oysters

The concentration of cadmium in the New Zealand dredge oyster Tiostrea lutaria (commonly known as a Bluff oyster) is sufficiently high so that the ingestion of just one oyster can more than double a normal daily dietary intake of cadmium for a New Zealand adult. A survey of 75 adults (18-76 years old) associated with the oyster fishing industry in Bluff, Southland, New Zealand, was carried out before and at the end of the oyster season. Preseason intakes (from dietary history questionnaires and from 3-day fecal collections) of cadmium, selenium, zinc, copper, and manganese were normal for a New Zealand adult not consuming Bluff oysters. The subjects were classified according to their reported average oyster consumption during the 6 months of the oyster fishing season; the subjects who consumed more oysters were more likely to smoke cigarettes. The end-season fecal output of cadmium confirmed the reported average oyster intakes: Category I (0-5 oysters/week): 15 +/- 8 (mean +/- SD) micrograms Cd/day; Category II (6-23 oysters/week): 84 +/- 134 micrograms Cd/day; Category III (24-71 oysters/week): 129 +/- 144 micrograms Cd/day; Category IV (72+ oysters/week): 233 +/- 185 micrograms Cd/day. The fecal output of selenium as well was increased by the consumption of many oysters but the fecal outputs of zinc, copper, and manganese were not. Using fecal cadmium excretion to predict dietary cadmium intake, 8-15% of the subjects in this study were identified as having an intake of cadmium which has been associated with an increased prevalence of tubular proteinuria. The highest individual daily fecal excretion of cadmium at the end of the season was 580 micrograms Cd/day, i.e., a daily excretion equivalent to more than 10 times above the weekly intake provisionally considered tolerable (400-500 micrograms Cd/week; WHO, 1972). Continued investigations on this population group will determine whether there are any health consequences of these extremely high cadmium intakes.     

Heavy Metal Levels in Suspended Sediments, Crassostrea gigas, and the Risk to Humans

Wild Pacific oyster (Crassostrea gigas) and sediment, both resuspended and suspended (RSS) samples (<53 μm), were collected over an 8-month period from a coastal estuary in Baynes Sound, BC, Canada. Stable isotope analysis (δ¹³C, δ¹⁵N) was used to determine, first, if RSS sediments was an important dietary source to C. gigas and, second, if so, whether it served as a significant dietary exposure route for Cd, Cu, Pb, and Zn. Although RSS sediments were high in trace metals such as Cd, Pb, Zn, and notably Cu, stable isotope signatures for oyster tissues did not correspond to those of RSS sediments. These results indicate that RSS sediments are not a significant source of metal to the oysters. In addition, we compared the potential risk to humans ingesting C. gigas with levels of Cd, Cu, Pb, and Zn from this study to the current Agency for Toxic Substances and Disease Registry (ATSDR) chronic oral minimal risk levels (MRLs) using current Canadian consumption guidelines of three oysters/week. Cu, Pb, and Zn levels were below MRL levels, with Cd exceeding the recommended 0.2 μg/kg/day MRL level fourfold. Total daily intake levels (TDI) for Cd were additionally calculated and either reached or exceeded the Food and Agriculture Organization/World Health Organization (FAP/WHO) reference dose of 1 μg/kg/day for Cd consumption in Canadians. Our results indicate that the current Canadian Cd consumption guidelines do not protect individuals consuming the maximum recommended levels of wild oysters.     

The bioconcentration and metabolism of chlorpyrifos by the eastern oyster,Crassostrea virginica

Eastern oysters (Crassostrea virginica) were exposed to [14C]chlorpyrifos (O,O-diethyl-O-[3,5,6-trichloro-2-pyridyl] phosphorothioate) at an average measured seawater concentration of 0.6 microg/L under flow-through conditions for 28 d. The compound O,O-diethyl-O-(3,5-dichloro-6-methylthio-2-pyridyl)phosphorothioate (DMP) was extracted and identified as the single metabolite observed, and this metabolite constituted the majority of the total [14C] activity in the oyster at all sampling times. Once oysters were exposed to clean water, both chlorpyrifos and DMP residues cleared rapidly from whole oysters, with elimination half-lives of <3 d. A simple two-compartment uptake/elimination model was adequate to describe total [14C] activity in whole oysters, edible tissue, and oyster liquor. The average bioconcentration factors (BCFs) for total [14C] activity in whole oysters, edible tissue, and oyster liquor were 565, 1,400, and 35 ml/g, respectively. The parent [14C]chlorpyrifos accumulated to a peak residue concentration of 135 microg/kg in whole oyster tissue, representing an empirical [14C]chlorpyrifos BCF value in the oyster of approximately 225 ml/ g; the BCF value for [14C]chlorpyrifos was lower than the BCF for total [14C] activity in whole oysters and edible tissue because of extensive metabolism to DMP and oyster elimination processes.     

Bioassessment of an Appalachian Headwater Stream Influenced by an Abandoned Arsenic Mine

Recent debate concerning the modification of safe drinking water standards for arsenic (As) has led to increased awareness of the risks As poses to both humans and the environment. However, few studies have examined the effects of As on the diversity and composition of aquatic assemblages in streams. Benthic macroinvertebrate surveys, chemical analysis of water column and sediment, and laboratory toxicity tests were conducted to assess effects of an abandoned As mine on a headwater stream, and to determine the primary component of toxicity. The average 48-hr LC50 value for Daphnia magna was 4316 μg As/L, and the average 96-hr LC50 value for Lepidostoma spp. was 2138 μg As/L. Reproduction was significantly reduced for D. magna at concentrations ≥312 μg As/L in water column laboratory bioassays, and for treatments in bioassays with sediments containing elevated As (≥2630 mg/kg). These results support the findings of the in-stream benthic macroinvertebrate survey as the density and percent Ephemeroptera + Plecoptera, + Trichoptera (EPT) were substantially lower at sites downstream of the mine compared to upstream reference sites. Results of bioassays comparing the toxicity of As-contaminated site water and upstream reference water spiked with As salts suggest that As is the primary component of toxicity impacting the stream. Measured As concentrations at downstream sites were above the recommended Criterion Maximum Concentration of 340 μg As/L and Criterion Continuous Concentration of 150 μg As/L for protection of aquatic life published by the United States Environmental Protection Agency. At the study site, elevated As concentrations likely prevent recruitment of benthic macroinvertebrates and recovery of the perturbed headwater stream.     

Transfer of cadmium in a phytoplankton-oyster-mouse food chain

The trophic transfer of cadmium (Cd) was studied in a phytoplankton-oyster-mouse food chain. Phytoplankton, grown in a continuous culture chemostat system containing CdCl₂ plus the isotope¹⁰⁹Cd, accumulated 70% of the total supplied cadmium. Oysters filtered out 85 to 95% of the phytoplankton. The rate of oyster Cd accumulation at 15 C increased linearly with seawater Cd concentration according to: y=0.066X – 0.15 (n =12, r=0.96); where X=g Cd/L seawater (between 2 and 22) and y=g Cd/g dry wt oyster/ day. About 59% of the Cd accumulated by the oysters came from the phytoplankton food source and 41% from the cadmium dissolved in the water. Sixty-one percent of the total supplied cadmium was retained in the whole soft body of the osyters. Mice fed 0.4 g of oyster-bound Cd per g of diet, retained 0.83% of the dietary cadmium consumed. Mouse kidney retention for organic oyster-bound cadmium was 0.14%. Extrapolation of these results to human risk assessment indicates that moderate consumption of oysters, which are not highly contaminated with cadmium, poses no significant health risk in terms of elevating kidney cadmium levels.     

Toxicity and bioconcentration of BHC and lindane in selected estuarine animals

Flow-through, 96-hr bioassays were conducted to determine the acute toxicity of technical BHC and lindane to several estuarine animals. Test animals and their respective 96-hr lindane LC50 values were: mysid(Mysidopsis bahia), 6.3 µg/L; pink shrimp(Penaeus duorarum), 0.17 µg/L; grass shrimp(Palaemonetes pugio), 4.4 µg/L; sheepshead minnow(Cyprinodon variegatus), 104 µg/L; and pinfish(Lagodon rhomboides), 30.6 µg/L. The 96-hr LC50 values for pink shrimp and pinfish exposed to BHC were 0.34 and 86.4 µg/L, respectively.Two BHC bioconcentration studies were conducted with the oyster,Crassostrea virginica, and pinfish. After 28 days exposure, oysters bioconcentrated an average of 218 X the BHC measured in exposure water, while pinfish bioconcentrated 130 X in their edible tissues and 617 X in offal. After one week in BHC-free sea water, no detectable residues were measured in oysters or pinfish.Gulf Breeze Contribution No. 288.     

Assessment of the genotoxic potential of contaminated estuarine sediments in fish peripheral blood: laboratory versus in situ studies

Juvenile Senegalese soles (Solea senegalensis) were exposed to estuarine sediments through 28-day laboratory and in situ (field) bioassays. The sediments, collected from three distinct sites (a reference plus two contaminated) of the Sado Estuary (W Portugal) were characterized for total organic matter, redox potential, fine fraction and for the levels of metals, polycyclic aromatic hydrocarbons (PAHs) and organochlorines, namely polychlorinated biphenyls (PCBs) and dichloro diphenyl tricholoethane plus its main metabolites (DDTs). Genotoxicity was determined in whole peripheral blood by the single-cell gel electrophoresis (SCGE or “comet”) assay and by scoring erythrocytic nuclear abnormalities (ENA). Analysis was complemented with the determination of lipid peroxidation in blood plasma by the thiobarbituric acid reactive substances (TBARS) protocol and cell type sorting. The results showed that exposure to contaminated sediments induced DNA fragmentation and clastogenesis. Still, laboratory exposure to the most contaminated sediment revealed a possible antagonistic effect between metallic and organic contaminants that might have been enhanced by increased bioavailability. The laboratory assay caused a more pronounced increase in ENA whereas a very significant increase in DNA fragmentation was observed in field-tested fish exposed to the reference sediment, which is likely linked to increased lipid peroxidation that probably occurred due to impaired access to food. Influence of natural pathogens was ruled out by unaltered leukocyte counts. The statistical integration of data correlated lipid peroxidation with biological variables such as fish length and weight, whereas the genotoxicity biomarkers were more correlated to sediment contamination. It was demonstrated that laboratory and field bioassays for the risk assessment of sediment contamination may yield different genotoxicity profiles although both provided results that are in overall accordance with sediment contamination levels. While field assays may provide more ecologically relevant data, the multiple environmental variables may produce sufficient background noise to mask the true effects of contamination.     

Assessment of Diazinon Toxicity in Sediment and Water of Constructed Wetlands Using Deployed <Emphasis Type="Italic">Corbicula fluminea</Emphasis> and Laboratory Testing

Constructed wetlands for mitigation of nonpoint agricultural runoff have been assessed for their ability to decrease potential toxicity from associated contaminants. After a simulated runoff event, constructed wetlands positioned in series were used to measure the effects of the organophosphate insecticide diazinon. Water, sediment, and plant samples from five sites were analyzed for diazinon concentrations from 0.5 hours to 26 days; peak concentrations were measured in sediment after 0.5 hours (268.7 μg/kg) and in water and plant tissue after 3 hours (121.71 μg/L and 300.7 μg/kg, respectively). Cholinesterase activity and changes in shell growth were measured from Corbicula fluminea deployed at corresponding sites. Water collected after 9 hours from all wetland sites contained diazinon concentrations sufficient to cause toxicity to Ceriodaphnia dubia, but not to Pimephales promelas. C. dubia survival was decreased in water sampled through 7 days from the site nearest runoff introduction, whereas C. fluminea deployed at this same site experienced 100% mortality after 26 days. Clams from lower sites survived wetland conditions, but growth and ChE activity were significantly decreased lower than that of clams from a control site. C. dubia exposed to water from these sites continued to have decreased survival throughout the 26-day sampling. Sediment sampled from 48 hours through 14 days at the lowest wetland site decreased the laboratory survival of Chironomus dilutus, and sediment from upper sites elicited an effect only on day 26. Although wetland concentrations of aqueous diazinon were decreased lower than toxic thresholds after 26 days, decreased ChE activity in deployed clams provided evidence of residual diazinon effects to deployed organisms. All programs and services of the United States Department of Agriculture are offered on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, marital status, or handicap. Mention of a pesticide in this article does not constitute a recommendation under the Federal Insecticide, Fungicide, and Rodenticide Act as amended. Names of commercial products are included for the benefit of the reader and do not imply endorsement or preferential treatment by the United States Department of Agriculture.     

Uptake of cadmium from Pacific oysters (Crassostrea gigas) in British Columbia oyster growers

Background

Pacific oysters along the North American coast from Washington to Alaska contain concentrations of cadmium (Cd) that are high by comparison with Atlantic oysters, frequently exceeding 2 μg/g wet weight, but it is unclear whether this Cd is absorbed by consumers.

Objectives

To determine the effect of oyster consumption on Cd in blood and urine among a group with high oyster consumption.

Methods

Sixty-one non-smoking oyster growers and family members with a mean age of 47.3±7.6 years (range 33-64) were interviewed by telephone to assess their oyster consumption and other sources of Cd exposure at present and 5 years prior to the start of oyster farming. Their blood and urine Cd concentrations were measured.

Results

The geometric mean Cd concentration in blood was 0.83 μg/L and in urine was 0.76 μg/g creatinine. Thirty-six percent of participants had urinary Cd levels above 1 μg/g creatinine and 5% were above 2 μg/g creatinine. Recent (last 12 months) and long-term oyster consumptions were positive predictors of blood Cd but did not directly predict urinary Cd. The optimal model for predicting the variance in blood Cd included recent intake of oyster-derived Cd, serum iron concentration and recent ketchup consumption (R²=0.34, p=0.00004), with the latter two variables showing a protective effect. The factors found to predict urinary Cd were blood Cd concentration and duration of oyster farming. A rise in blood Cd was observed after 12 years of farming oysters, likely caused by higher consumption of oysters during this period.

Conclusions

Oyster-derived Cd is bioavailable and affects body stores of the metal.     

Acute Toxicity and Acetylcholinesterase Inhibition in Grass Shrimp (<Emphasis Type="Italic">Palaemonetes pugio</Emphasis>) and Oysters (<Emphasis Type="Italic">Crassostrea virginica</Emphasis>) Exposed to the Organophosphate Dichlorvos: Laboratory and Field Studies

The use of various organophosphates to control mosquito populations is a common practice across the globe. We review the literature (LC50s) on dichlorvos, the primary breakdown product of Dibrom, and use laboratory and field experiments to determine the lethal and sublethal (bioassays) effects of dichlorvos on two widely distributed and ecologically important estuarine invertebrate species, the marsh grass shrimp, Palaemonetes pugio and the Eastern oyster, Crassostrea virginica. Laboratory results based on LC50s and sublethal acetylcholinesterase (AChE) inhibition activity bioassays indicate that adult grass shrimp are more sensitive (approximately 500 x ) to dichlorvos than juvenile oysters. Although potentially an important factor for intertidal or shallow-dwelling estuarine organisms, the toxicity of dichlorvos was not enhanced in the presence of simulated sunlight for adult P. pugio. The most notable decreases in AChE activity were for grass shrimp and oysters exposed to dichlorvos concentrations above those considered ecologically relevant. In field experiments, both species were deployed in cages in unsprayed (n = 2) and sprayed (n = 3) sites and water samples collected pre- and post-spraying. Quantifiable dichlorvos levels were measured at the two narrowest creek treatment sites following mosquito spraying, suggesting that overspray can occur and there was evidence of a sublethal AChE response at these same sites. However, experiments at the widest creek revealed no measurable dichlorvos or sublethal responses. Results from this research suggest that adult grass shrimp are more sensitive to dichlorvos than juvenile oysters. Spraying near small tidal creeks may have measurable impacts on resident species, while larger (wider) creeks appear to be capable of buffering organisms from transient fluxes of mosquito control agents that may enter the system.     

Estimation of Target Hazard Quotients and Potential Health Risks for Metals by Consumption of Seafood in Taiwan

The purpose of this paper is to describe the impact of metal pollution on the main seafood and assess the potential health risk from consuming the contaminated seafood in Taiwan. The results of geometric mean (GM) metal concentrations in various seafood showed that the copper, zinc, and arsenic concentrations in oysters were significantly (p < 0.001) higher than those in the other seafood by about 1,057, 74.3, and 56.2 times, respectively. The green color found in the oysters was due to high GM copper and zinc concentrations of 909 (ranging from 113–2,805) and 1,293 (ranging from 303–3,593) μg/g dry wt, respectively. In addition, using a maximum consumption rate of 139 g/day of oysters for individuals, calculations yield target hazard quotients (daily intake/reference dose) of below 1 for cadmium and mercury and high values of 1.61, 9.33, and 1.77 for inorganic arsenic, copper, and zinc in adults, respectively. The various lifetime cancer risks for inorganic arsenic (maximum exposed individuals risk ranging from 9.93 × 10⁻⁶ to 3.11 × 10⁻⁴) might be caused by consuming different seafood in Taiwan. The highest risk estimate for inorganic arsenic was 5.10 × 10⁻⁴ for consumption of oysters by Machu Islands residents. The long-term exposure of metals through consumption of oysters, especially for some high-risk groups, could be dangerous. Taking inorganic arsenic for example, a 10⁻⁶ upper limit on lifetime risk as the health protection standard would require maximum oyster residue levels of approximately 0.0076–0.056 μg/g wet wt, for consumption rates of 139–18.6 g/d. In the light of known risks to public health, the government should issue an immediate warning to the public to refrain from eating all seafood harvested from the Taiwan coastal areas, especially the Hsiangshan area and the Machu Islands. Received: 18 January 1998/Accepted: 6 July 1998     

Metal Content and Toxicity of Produced Formation Water (PFW): Study of the Possible Effects of the Discharge on Marine Environment

A preliminary chemical and ecotoxicological assessment was performed on the produced formation water (PFW) and superficial sediment around a gas platform (Fratello Cluster), located in the Adriatic Sea (Italy), in order to evaluate the effects of PFW discharged from the installation. The ecotoxicological bioassays, with the marine bacterium Vibrio fischeri and the sea urchin Paracentrotus lividus, were associated with chemical data to estimate the possible effects on living organisms. PFW collected on the platform was toxic, but no significant effect was recorded on marine sediment. Only the sediment station nearest to the discharge point showed higher values of some contaminants (zinc and arsenic) in comparison to other sites and only some stations showed low toxicity.     

Heavy Metal Contamination in the Cultivated Oyster <Emphasis Type="Italic">Crassostrea rivularis</Emphasis> and Associated Health Risks from a Typical Mariculture Zone in the South China Sea

With the rapid development of mariculture in potentially contaminated regions in China and the world, food safety, is a growing concern. To evaluate heavy metals and their associated health risks in the cultivated oyster Crassostrea rivularis, the concentrations of heavy metals (Cd, Cr, Pb, Zn) in oysters and water/sediment were examined in a typical mariculture environment (Kaozhou Bay, South China Sea). Trends in the seasonal dynamics of heavy metals in oysters revealed a potential synergistic effects among the concentrations of Cd, Cr, and Zn; trends associated with Pb were less clear, although the ability of oysters to bioaccumulate and depurate Pb was excellent. Bioconcentration factors (BCF) indicated that C. rivularis has a strong ability to accumulate heavy metals, and the BCF was the highest for Zn (2.32?×?10⁵), followed by Cd (6.84?×?10⁴), Pb (2.77?×?10⁴) and Cr (1.23?×?10³) through the four seasons. Results showed that Cd concentrations in oysters could pose a risk to human health (HQ?>?1). This study, therefore, suggests that there are potential human health risks due to heavy metal exposure through the consumption of C. rivularis from mariculture zones in South China Sea.     

PCBs in sediments and oysters of Manila Bay,the Philippines

Polychlorinated biphenyls (PCBs) were analyzed in sediment and oyster samples from coastal sites inside Manila Bay. Concentrations for 13 individual PCB congeners and total PCBs are reported herein. Median ΣPCB concentration in sediments was 0.46 ng g^?1 dry weight (range 0.10–1.5 ng g^?1) and in oysters it was 15 ng g^?1 dry weight (range 7–73 ng g^?1). The most contaminated areas of the bay were the coastal zones of Metropolitan Manila and Bulacan province. A significant correlation (p < 0.01) was found between ΣPCB concentrations in oysters and in sediments. PCB concentrations measured in the bay sediments were below acute toxic levels to marine biota. Nevertheless, consumption of oysters by human population living around the bay might originate ΣPCB intake rates estimated at about 2.5 times lower than the tolerance limit. Further environmental surveillance is recommended in order to prevent public health risks that may be posed by these chemicals.