Range of the perfluorooctanoate (PFOA) safe dose for human health: An international collaboration.

Many government agencies and expert groups have estimated a dose-rate of perfluorooctanoate (PFOA) that would protect human health. Most of these evaluations are based on the same studies (whether of humans, laboratory animals, or both), and all note various uncertainties in our existing knowledge. Nonetheless, the values of these various, estimated, safe-doses vary widely, with some being more than 100,000 fold different. This sort of discrepancy invites scrutiny and explanation. Otherwise what is the lay public to make of this disparity? The Steering Committee of the Alliance for Risk Assessment (2022) called for scientists interested in attempting to understand and narrow these disparities. An advisory committee of nine scientists from four countries was selected from nominations received, and a subsequent invitation to scientists internationally led to the formation of three technical teams (for a total of 24 scientists from 8 countries). The teams reviewed relevant information and independently developed ranges for estimated PFOA safe doses. All three teams determined that the available epidemiologic information could not form a reliable basis for a PFOA safe dose-assessment in the absence of mechanistic data that are relevant for humans at serum concentrations seen in the general population. Based instead on dose-response data from five studies of PFOA-exposed laboratory animals, we estimated that PFOA dose-rates 10-70 ng/kg-day are protective of human health.

Evaluation of Clostridium perfringens as a tracer of sewage contamination in sediments by two enumeration methods.

A traditional method of enumerating Clostridium perfringens using membrane filtration (MF) as an indicator of fecal contamination was compared to recently developed rapid method using Rapid Fung Double Tube (RFDT) in an evaluation to characterize the extent of sewage contamination in sediments of the Great Lakes. Evaluation of these two methods included determining C. perfringens concentrations and recovery efficiencies from sewage, sewage-spiked sediments, and water (surface and bottom) and sediment samples collected from two Great Lakes. The RFDT method proved to be a superior method for identifying C. perfringens in lake sediments compared to MF, as it had higher recovery efficiency and was more rapid, reliable, simple, and effective. This study provides biological evidence of the long-term deposition and movement of sewage particulates in the Great Lakes environment and demonstrates the potential usefulness of C. perfringens as a tracer for sewage contamination using a reliable enumeration method.

Protective effect of Coleus aromaticus Benth (Lamiaceae) against naphthalene-induced hepatotoxicity.

OBJECTIVE: To investigate protective effect of Coleus aromaticus leaf extract against naphthalene induced hepatotoxicity in rats. METHODS: Eighteen male rats were divided into three groups. Group I rats were treated as control. Group II rats were intraperitoneally administered with naphthalene (435 mg/kg b.wt) dissolved in corn oil once a day for a period of 30 days. Group III rats were treated with leaf extract (100 mg/kg b.wt) dissolved in 0.9% saline and naphthalene (435 mg/kg b.wt) dissolved in corn oil once a day for a period of 30 days. RESULTS: Significant protective effect was observed against naphthalene induced liver damage, which appeared evident from the response levels of marker enzymes (aspartate transaminase, alanine transaminase, acid phosphatase, alkaline phosphatase and lactate dehydrogenase). The biochemical components viz. triglycerides, free fatty acids, cholesterol acyl transferase, high-density lipoprotein, low-density lipoprotein, cholesterol and bilirubin were found to be increased in liver and serum of naphthalene stressed rats when compared to control. CONCLUSION: Treatment of naphthalene intoxicated rats with plant extract reversed these distorted parameters to near normal levels. Liver histology showed supportive evidence regarding the protective nature of plant extract against fatty changes induced by naphthalene. The present study provides a scientific rationale for using C. aromaticus in the management of liver disorders.

The preparation of the rice coral Montipora capitata nubbins for application in coral-reef ecotoxicology.

Securing adequate and appropriate source material for coral-reef ecotoxicology studies is a significant impediment to conducting various experiments supporting the goal of conserving coral-reef ecosystems. Collecting colonies from wild stocks may be counter to protecting coral reef populations. To address this issue the rice coral Montipora capitata was used to generate sufficient genetically identical nubbins for research purposes. Growth and survival rates of these laboratory-prepared M. capitata nubbins were studied over a period of 90 days. The resulting data support the conclusion that the laboratory-prepared M. capitata nubbins showed successful growth and survival rates and are the best solution to solve the source material issue for lab experimentation. This paper describes the laboratory method used for the preparation and maintenance of these M. capitata nubbins and discusses the benefits and difficulties of using these nubbins in ecotoxicity studies.

Immunotoxic effects of nickel in the mud crab Scylla serrata.

The presence of xenobiotic contaminants especially metals in coastal waters is a major concern as they are immunotoxic to aquatic animals even at low concentrations. In our present study, mud crab Scylla serrata was exposed to three sublethal concentrations (0.4, 0.6 and 0.8 mg/L) of nickel for 30 days under laboratory conditions and the alterations of hematological parameters like haemocyte count, clotting time, haemocyte viability, protein content and immunomodulatory components like phenoloxidase, phagocytosis and superoxide anion generation were measured. In addition, the accumulation patterns of nickel were measured in gills, hepatopancreas and ovary. The accumulation was more in gills when compared to hepatopancreas and ovary of crabs exposed to nickel and was not detected in the control crabs. The results revealed a significant (P<0.05) induction of superoxide anion generation and phagocytosis activity in the haemolymph of the crabs exposed to nickel when compared to control. On the contrary, the rest of the parameters were significantly (P<0.05) reduced in the experimental groups when compared to the control. All the studied parameters exhibited a concentration dependent response.

Nutritional composition of three estuarine bivalve mussels, Perna viridis, Donax cuneatus and Meretrix meretrix.

The present study determined the nutrient composition of three bivalve mussels. The biochemical constituents (protein, carbohydrate, lipid and vitamins), minerals (iron, copper, zinc, calcium, magnesium, and manganese) and carbon, nitrogen and calorific values were evaluated. There was a high degree of variation in biochemical constituents and mineral components among the tested mussels. Perna viridis exhibited good nutritional composition when compared with Donax cuneatus and Meretrix meretrix. The results of this study showed that the samples possessed appreciable quantities of all the dietary elements tested, which could make them partial or complete substitutes for conventional seafood.

DNA damage and cell necrosis induced by naphthalene due to the modulation of biotransformation enzymes in an estuarine crab Scylla serrata.

The sublethal effect of naphthalene (2.5, 5, and 10 mg L(-1)) was studied in an estuarine crab Scylla serrata with reference to macromolecular changes. Biotransformation enzymes such as cytochrome P450, cytochrome b(5), NADPH cytochrome P450 reductase, aryl hydrocarbon hydroxylase, glutathione-S-transferase, and UDP-glucuronyl transferase were elevated in the hepatopancreas of naphthalene-exposed crabs in comparison with control. Remarkable amount of DNA damage and cell necrosis was observed in hepatopancreas, hemolymph, and ovary of the crabs exposed to naphthalene, when compared with control. For all the parameters studied, a concentration-dependent gradient of the changes was observed. The expression of DNA damage and cell necrosis suggests an increased production of oxidants during naphthalene metabolism.

Effluent toxicity test using developmental stages of the marine polychaete Hydroides elegans.

The US Environmental Protection Agency (USEPA) has established a suite of methods that use coastal invertebrate species as bioassay organisms to test industrial and domestic effluent as well as coastal waters for potential toxicity. Although these methods are used globally, the potential of such toxicity tests has not been adequately explored for Asian coastal waters. This study describes bioassay utilizing the gametes of Hydroides elegans to monitor coastal water quality and is based on the sensitivity of H. elegans embryo and larva to different concentrations of effluents and water samples collected from different regions of east coast of India. Among the water samples collected from different regions, seawater from Ennore station showed decrease in percentage of development, and 25% effluent concentration led to development arrest of H. elegans embryos. The different morphological effects produced by effluents clearly reflect the defect in early differentiation of embryonic cells. Since fertilization can be inhibited in the presence of any xenobiotic, both fertilization and early development can be used as a biological indicator for a rapid bioassay to monitor pollution. Toxicity tests utilizing early life stages of H. elegans are suitable for the assessment of effects produced by low levels of pollutants due to their high sensitivity to various contaminants relative to other marine species and also due to the relative simplicity of the bioassay.

Protective effect of Operculina turpethum against 7,12-dimethyl benz(a)anthracene induced oxidative stress with reference to breast cancer in experimental rats.

Reactive oxygen species (ROS) directly or indirectly involves in multistage process of carcinogenesis. Antioxidant activity of methanolic extract of Operculina turpethum stems (MEOT) on 7,12 dimethylbenz(a)anthracene (DMBA) induced breast cancer was investigated in female Sprague-Dawley rats. Changes in the levels of lipid peroxidation and antioxidants system was evaluated in addition to tumour development. Twenty four female rats were divided into four groups: control, DMBA, DMBA+MEOT and MEOT. In the DMBA group, rats were intragastrically administered with 20 mg of DMBA using corn oil as vehicle. Animals of DMBA+MEOT group received a single dose of 20 mg of DMBA dissolved in corn oil intragastrically followed by O. turpethum extract (100 mg/kg body weight), while MEOT group received O. turpethum extract (100 mg/kg body weight) intragastrically daily for a period of 45 days. After the experimental period of 45 days, oxidative stress parameters were assessed in serum, liver and breast of both control and experimental groups. In addition to this, tumour weight of breast was also assessed. A significant increase in lipid peroxidation levels were observed in the tested samples of cancer induced rats while the activities of enzymic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and non-enzymic antioxidants like glutathione (GSH), ascorbic acid (Vitamin C) and alpha-tocopherol (Vitamin E) were decreased in cancer-bearing animals when compared to control animals. A significant (P<0.05) increase in the tumour weight was observed in the breast of DMBA group and the breast tumour weight decreased significantly (P<0.05) in the DMBA+MEOT groups. Oral administration of MEOT remarkably reduced the lipid peroxidation activity and increased the antioxidants level in drug treated animals and decreased the tumour weight significantly (P<0.05). This result suggests that MEOT shows antioxidant activity and play a protective role against DMBA induced breast cancer.

Sublethal effect of silver and chromium in the green mussel Perna viridis with reference to alterations in oxygen uptake, filtration rate and membrane bound ATPase system as biomarkers.

Perna viridis is an ideal animal for studying the impairment caused by the effects of heavy metals that are often detected in coastal areas. Preliminary bioassay tests revealed that the lethal (LC(100)), median lethal (LC(50)) and sublethal (LC(0)) concentration of silver and chromium to P. viridis were 6.5, 4.0, 2.0 mg l(-1) and 4.5, 2.5, 1.0 mg l(-1), respectively. Toxic effect of silver and chromium was evaluated in the green mussel P. viridis, with reference to oxygen consumption, filtration rate and ATPase system in laboratory experiments. These parameters were selected as the end point of sublethal stress. Oxygen consumption and filtration rates were calculated as a measure of decline in the dissolved oxygen level and algal concentration (feed) in the aquaria water, respectively. Silver and chromium affects both oxygen consumption and filtration rate significantly (P<0.01) at 96 h when compared to control. The activity of ATPases system in the gills, hepatopancreas, ovary and muscle of mussels were inhibited by silver and chromium indicating that metals exerted significant toxic effect. The inhibition of Na(+)K(+) ATPase, Ca(2+) ATPase and Mg(2+) ATPase in the mussels were significant (P<0.05) for silver and highly significant (P<0.01) for chromium, which indicates that chromium was more toxic to mussels when compared to silver. The assessment of oxygen consumption, filtration and ATPases system can thus be used as a valid biomarker in aquatic ecotoxicology studies.

Free radical scavenging activity of the marine mangrove Rhizophora apiculata bark extract with reference to naphthalene induced mitochondrial dysfunction.

Rhizophora apiculata bark extract was tested for its free radical scavenging activity and protective role against mitochondrial dysfunction in naphthalene stressed rats. Lipid peroxidation activity was increased and activity of mitochondrial enzymes (cytochrome-c-oxidase, NADH-dehydrogenase, alpha-ketoglutarate dehydrogenase and succinate dehydrogenase) and glutathione was decreased in the liver and kidney of rats intoxicated with naphthalene when compared to control rats. Intraperitoneal administration of plant extract significantly reduced the lipid peroxidation, increased the activity of mitochondrial enzymes and increased glutathione to near control levels. These results suggest that the sulfated polysaccharides in R. apiculata play a protective role through their free radical scavenging properties.

Dietary ascorbic acid and alpha-tocopherol mitigates oxidative stress induced by copper in the thornfish Terapon jarbua.

The protective effects of vitamins C and E against oxidative stress were evaluated in various tissues of thornfish Terapon jarbua exposed to copper. Preliminary bioassay tests performed with copper and T. jarbua revealed that 4.0, 2.5 and 1.0 mg L(-1) of copper were lethal (LC(100)), medial lethal (LC(50)) and sublethal (LC(0)) respectively. Oxidative stress parameters viz. lipid peroxidation, superoxide dismutase, catalase, glutathione peroxidase, and glutathione were evaluated in control and experimental fishes. Lipid peroxidation activity increased in tissues of copper exposed fishes, while the antioxidant system exhibited a reduction in their activity. On the contrary copper stressed fishes fed with vitamins C and E enriched pellet feed showed significant reduction in lipid peroxidation activity and the antioxidant levels increased reaching near normal levels comparable to control values. Bioaccumulation of copper was studied in addition to oxidative stress. Substantial copper residue was detected in the tissues of T. jarbua exposed to copper and the level of copper in tissues reduced when the fishes were treated with vitamins ensuring copper depuration and thereby protecting them against stress. We concluded that vitamin supplementation offered significant reduction of the oxidative stress mediated by copper and we discuss the possible application of vitamins in costal aquaculture process.

Changes in oxygen consumption and respiratory enzymes as stress indicators in an estuarine edible crab Scylla serrata exposed to naphthalene.

The sublethal effect of naphthalene was studied on the physiology of a mud crab Scylla serrata. The 96 h acute toxicity of naphthalene was determined and found to be 28 mg 1(-1) (LC100), 18 mg 1(-1) (LC50), 10 mg 1(-1) (LC0) respectively. The 30 days sublethal effect (LC0) 9 mg 1(-1), 8 mg 1(-1), 10 mg 1(-1), of naphthalene was investigated in the crab S. serrata with reference to oxygen consumption and changes in the activity of respiratory enzymes. The results indicated that naphthalene caused disturbance in the normal physiology of the crab. The bioaccumulation of naphthalene was also investigated in gills, hepatopancreas, haemolymph and ovary. The consumption of oxygen increased in the naphthalene medium when compared with that of the crabs exposed to naphthalene free medium. A decreased trend in the activity of respiratory enzymes such as lactate dehydrogenase (LDH), isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), alpha-ketoglutarate dehydrogenase (alpha-KDH) and glutathione (GSH) were recorded in the hepatopancreas, ovary and gills of S. serrata for all the tested concentrations of naphthalene and the results were analyzed for their significance.

Impact of fertilizer (urea) on oxygen consumption and feeding energetics in the fresh water fish Oreochromis mossambicus.

The effects of urea on survival, food utilization and oxygen consumption of the fresh water fish Oreochromis mossambicus were studied. The percentage survival of O. mossambicus when exposed to different concentrations of urea at 24, 48, 72 and 96h exposures was noted and it was found that 22,000 and 38,000mgL(-1) urea concentration were sublethal and lethal, respectively. The median lethal concentration, which killed 50% of the fishes during 96h exposure, was 28,000mgL(-1). Rearing the fish in increasing sublethal concentrations of urea, it was found that the feeding rate decreased from 34.341±7.067mgglivefish(-1)d(-1) (control) to 13.921±2.315mgglivefish(-1)d(-1) at the highest concentration of urea (22,000mgL(-1)). Growth rate was drastically reduced. The consumption of oxygen in O. mossambicus diminished from 0.962±0.208 to 0.645±0.118mgglivefish(-1)h(-1) when reared in the highest sublethal concentration of urea.

Influence of insecticidal derivative (cartap hydrochloride) from the marine polycheate on certain enzyme systems of the fresh water fish Oreochromis mossambicus.

The activities of phosphatases and transaminases were studied in muscle and liver of the fresh water fish, Oreochromis mossambicus on exposure to different sublethal concentrations (0.25, 0.5, 0.75 and 1 mgl(-1)) of cartap hydrochloride (insecticidal derivative from marine polycheate) for 96 h. There was an overall decrease in phosphatases and transaminases activity in muscle and liver of the fish subjected to cartap hydrochloride.

Sublethal effect of naphthalene on lipid peroxidation and antioxidant status in the edible marine crab Scylla serrata.

The effect of naphthalene on lipid peroxidation and antioxidants status was studied in hepatopancreas, haemolymph and ovary of the Scylla serrata with reference to the active vitellogenic stage. There was an overall increase in lipid peroxidation activity in the tested samples. In contrast, the enzymatic (catalase, glutathione peroxidase, superoxide dismutase) and non-enzymatic antioxidants (vitamins C, E and glutathione) showed decreased activities for hepatopancreas, haemolymph and ovary.

Oxidative DNA damage induced by iron chloride in the larvae of the lace coral Pocillopora damicornis.

Biochemical and molecular biomarkers tools are utilized as early warning signatures of contaminant exposure to target and non-target organisms. The objective of this study was to investigate the sublethal effects of iron chloride to the larvae of the lace coral Pocillopora damicornis by measuring a suit of oxidative-stress biomarkers. The larvae were exposed to a range of sublethal concentrations of iron chloride (0.01, 0.1, 1, 10, and 100 ppm) for seven days. With reference to oxidative stress biomarkers, the no-observed effect concentration (NOEC) and the lowest observed effect concentration (LOEC) of iron chloride were observed to be 0.01 and 100 ppm respectively. At the end of the seventh day the antioxidant status of the larvae was evaluated by the levels of glutathione (GSH), glutathione peroxidase (GPX), glutathione reductase (GR), and glutathione-S-transferase (GST), in both experimental and control groups. For the quantification of cellular oxidative damage, lipid peroxidation (LPO) activity was determined in the same and the extent of DNA damage was assessed by the expression of DNA apurinic/apyrimidinic (AP) sites. Iron chloride exhibited a concentration-dependent inhibition of GSH and GPX and induction of GR, GST, LPO, and DNA-AP sites in the P. damicornis larvae when compared to the control group. The oxidative stress biomarkers of the larvae exposed to 0.1, 1, and 10 ppm of iron chloride did not show any significant overall differences when compared to the control group. However the activities of LPO, GSH, GPX, GR, GST and DNA-AP in the larval group exposed to 100 ppm of iron chloride exhibited statistically significant (P=0.002, 0.003, 0.002, 0.002, 0.005 and 0.007) differences when compared to the control group. The research results indicated that iron chloride in concentrations at the 100 ppm level caused oxidative stress in the P. damicornis larvae.

Reproductive dysfunction induced by naphthalene in an estuarine crab Scylla serrata with reference to vitellogenesis.

Biomarkers are useful tools for understanding complex interactions that elicit organisms response to environmental pollutants and their sublethal effects on organisms health. Effect of naphthalene on vitellogenin (VTG) and vitellin (VTN) were assessed in hepatopancreas, haemolymph and ovary of an estuarine crab Scylla serrata with reference to vitellogenic phases. In addition, the gonadosomatic index (GSI) was also assessed. Significant reductions in VTG and VTN contents were observed in hepatopancreas, haemolymph (VTG) and ovary (VTN). The GSI exhibited a decreasing trend in crabs exposed to naphthalene irrespective of the vitellogenic phases. We attempted to use the alterations in vitellogenic proteins and GSI as biomarkers of reproductive disturbances occurred in the crab due to naphthalene stress.

Interaction of potash and decis in the ecophysiology of a freshwater fish Oreochromis mossambicus.

Interaction of potash and decis in the ecophysiology of a freshwater fish, Oreochromis mossambicus, was studied. It was found that 300, 550 and 700 mgL(-1) of potash were sublethal (LC(0)), median lethal (LC(50)), and toxic (LC(100)) to O. mossambicus for 96h exposure, respectively. For decis, 96 h LC(100,) LC(50), and LC(0) was 0.4, 0.25, and 0.1 mgL(-1), respectively. Sublethal concentrations of potash and decis were exposed to fishes individually and in combination for 28 days. The results revealed that the combined effect of these chemicals was more highly toxic to food intake, growth, and conversion efficiencies than the individual chemicals. The marker enzymes (acid phosphatase, alkaline phosphatase, aspartate transaminase, alanine transaminase) were also analyzed in blood, liver and muscle. The enzyme activities were decreased in liver and muscle. On the other hand, serum exhibited increased activities of marker enzymes. The results were tested statistically and interpreted accordingly.

Antioxidant effect of the marine algae Chlorella vulgaris against naphthalene-induced oxidative stress in the albino rats.

Alcoholic extract of the marine algae Chlorella vulgaris was examined for its free radical scavenging effect with reference to naphthalene-induced lipid peroxidation in serum, liver, and kidney of rats. Initially, upon naphthalene intoxication (435 mg/kg body weight, intraperitoneally), the lipid peroxidation activity increased significantly (P < 0.001), and in contrast, the enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase) and non-enzymic antioxidants (glutathione, ascorbic acid, and alpha-tocopherol) levels decreased remarkably. When the naphthalene stressed rats were treated with Chlorella vulgaris extract (70 mg/kg body weight, orally), the lipid peroxidation activity reduced significantly (P < 0.001) and the activities of both the enzymic and non-enzymic antioxidants increased reaching near control values. The minimum concentration (70 mg/l) of the extract that exhibited maximum (85%) free radical scavenging activity was chosen for the experimental study. The present results suggest that Chlorella vulgaris extract exerts its chemo-preventive effect by modulating the antioxidants status and lipid peroxidation during naphthalene intoxication.