Paralytic shellfish toxins in Australian Southern Rock Lobster (Jasus edwardsii): Acute human exposure from consumption of hepatopancreas

Paralytic shellfish toxins (PST) were identified in the hepatopancreas of Southern Rock Lobster (Jasus edwardsii) during Alexandrium tamarense blooms in Tasmania, Australia. Human health risk from PST in lobsters was unknown – this study assesses exposure to PST from hepatopancreas consumption. Lobster hepatopancreas samples collected during blooms (n = 181) were mostly positive for PST (>88%), the highest concentration was 4032 μg STX-2HCl eq/kg. Consumer exposure to PST was estimated using a 2-D Monte Carlo model. Mean PST intake (pi) from hepatopancreas consumption (raw and cooked) was below the lowest-observed-adverse-effect-level (LOAEL) for PST (<2.0 μg/kg bw), however the 97.5th percentile pi for raw meals (2.64 μg/kg bw) exceeded the LOAEL. A total of 4.1% of raw hepatopancreas meals were estimated to exceed the LOAEL. Lobster hepatopancreas consumption during A. tamarense blooms may be concerning for a small proportion of consumers, particularly those that eat large meals at the bloom peak. However, when the model was re-run with PST concentration capped at the bivalve regulatory limit (800 μg STX-2HCl eq/kg) pi decreased, with the 97.5th percentile values below the LOAEL. Thus, issuing public health warnings and harvesting restrictions for lobsters when levels exceed 800 μg STX-2HCl eq/kg would reduce the probability of illness occurring.     

The accumulation characteristics and potential health risks of heavy metals in vegetables from reclaimed area of China

The reclamation of subsidence area was regarded as a useful pathway to rebuild landscape and ecosystem. However, the elevated concentrations of heavy metals in the reclaimed area may lead to potential environmental and health risks. This study was aimed at investigating the accumulation of heavy metals in the soils and vegetables, and evaluate the potential health risks to human beings via consuming these vegetables. The concentrations of heavy metals (Cd, Cu, Pb, and Zn) were measured by using inductively coupled plasma mass spectrometry. The elevated concentrations of heavy metals were found in the soil from the reclaimed area when compared with the background value. The concentrations of heavy metals were various among the different vegetable species. The heavy metal tolerance could be found in all the selected vegetables. The elevated concentrations of Cu, Pb, and Zn in the edible part of the selected vegetables indicated that the consumption of these vegetables may lead to potential health risk. The intake of soybean, radish, sweet potato, and mugwort may lead to potential health risks due to the elevated target health quotients. Chinese cabbage and pepper were regarded as the suitable vegetables which may help in reducing the potential health risk.     

DoMicrocystis aeruginosa toxins accumulate in the food web: a laboratory study

The accumulation ofMicrocystis aeruginosa hepatotoxins (microcystin-LR) in the phantom midge larvaChaoborus was studied in a 16 d laboratory experiment. In the cyanobacteria treatment,Chaoborus larvae were fed withDaphnia pulex juveniles which had been feeding for two days on a mixture ofScenedesmus obtusiusculus and toxicMicrocystis aeruginosa. In the control treatment theChaoborus larvae were offeredD. pulex raised onScenedesmus only. An HPLC analysis failed to detect any cyanobacteria toxin in theChaoborus larvae, indicating that the toxin was metabolized or excreted byD. pulex andChaoborus. There was a statistically significant increase in mortality of larvae in the cyanobacteria treatment, but no difference between treatments in pupation success ofChaoborus was observed.     

Preliminary investigations on the influence of suspended sediments on the bioaccumulation of two chlorobenzenes by the guppy (Poecilia reticulata)

In this study the uptake by guppies (Poecilia reticulata) of 1,2,3-trichlorobenzene (TCB) and hexachlorobenzene (HCB) from sediment-free water was compared with uptake in the presence of suspended sediment. The results show that the influence of suspended sediment on the uptake of chlorobenzenes varies with test compound. For TCB uptake was not influenced by the presence of suspended sediment. This is probably due to the large amount of the chemical which is dissolved relative to the amount which is present in the sorbed state. For the more hydrophobic HCB, the concentration found in the fish from the system with suspended sediment was significantly higher than in fish from the control experiment.     

Comparative Effects of Direct Cadmium Contamination on Gene Expression in Gills, Liver, Skeletal Muscles and Brain of the Zebrafish (Danio rerio)

The effects of cadmium (Cd) on gene expression were examined in four organs (gills, liver, skeletal muscles and brain) of the zebrafish. Adult male fish were subjected to three different water contamination pressures over periods of 7 and 21 days: control medium (C₀: no Cd added) and two contaminated media (C₁: 1.9 ± 0.6 μg Cd l⁻¹, and C₂: 9.6 ± 2.9 μg Cd l⁻¹). Fourteen genes involved in antioxidant defences, metal chelation, active efflux of organic compounds, mitochondrial metabolism, DNA repair and apoptosis were selected and their expression levels investigated by quantitative real-time PCR. Cadmium concentrations were determined in the four organs and metallothionein (MT) protein levels investigated in brain, liver and gills. Although skeletal muscle was a poor Cd-accumulating tissue, many genes were up-regulated at day 7: mt1, cyt, bax, gadd and rad51 genes. Three additional genes, c-jun, pyc and tap, were up-regulated in muscles at day 21 whereas bax, gadd and rad51 had returned to basal levels. Surprisingly, mt1 and c-jun were the only genes displaying a differential induction after 21 days in liver, although this organ accumulated the highest cadmium concentration. In brain, only mt1, mt2 and c-jun genes were up-regulated after 21 days. In gills, the highest response was observed after 7 days, featuring the differential expression of oxidative stress-response hsp70 and mitochondrial sod genes, along with genes involved in mitochondrial metabolism and metal detoxification. Then, after 21 days, the expression of almost every genes returned to basal levels while both mt1 and mt2 genes were up-regulated.     

Co-occurrence of Dinophysis tripos and pectenotoxins in Argentinean shelf waters

The species Dinophysis tripos is a widely distributed marine dinoflagellate associated with diarrheic shellfish poisoning (DSP) events, which has been recently identified as a pectenotoxin (PTX) producer. In two sampling expeditions carried out during austral autumns 2012 and 2013 along the Argentine Sea (≈38–56° S), lipophilic phycotoxins were measured by tandem mass spectrometry coupled to liquid chromatography (LC–MS/MS) in size-fractionated plankton samples together with microscopic analyses of potentially toxic phytoplankton. PTX-2, PTX-11 and PTX-2sa were recurrently detected in the 50–200 μm fractions, in association to D. tripos. PTX-2 was also widely distributed among the 20–50 μm fractions, mostly related to Dinophysis acuminata. Okadaic acid or its analogs were not detected in any sample. This is the first report of D. tripos related to PTX in the Argentine Sea and the first record of PTX-11 and PTX-2sa for this area. The morphological variability of D. tripos, including the presence of intermediate, small and dimorphic cells, is described. Also, the micro- and mesoplanktonic potential grazers of Dinophysis spp. were explored.     

The effects of K+ growth conditions on the accumulation of cesium by the bacterium Thermus sp. TibetanG6

The accumulation of cesium by the bacterium Thermus sp. TibetanG6 was examined under different K⁺ growth conditions. The effects of external pH and Na⁺ on the accumulation of cesium were also studied, and the mechanism involved was discussed. K⁺ regimes played an important role in the accumulation of cesium by the strain TibetanG6. The quantity of cesium accumulated (24 h) was much higher in K⁺-deficient regime than that in K⁺-sufficient regime. The pH and Na⁺ had different effects on the accumulation of cesium in the two K⁺ regimes. IR spectra analyses indicated that the biosorption is a process of homeostasis with cesium initially accumulated on the cell wall.     

The Health and Ecological Impacts of Organochlorine Pesticide Pollution in China: Bioaccumulation of Organochlorine Pesticides in Human and Fish Fats

The levels of organochlorine pesticides (OCPs) in the environment and foods have declined significantly in China since 1983, the year when their use in agriculture was officially banned. The levels today of these contaminants in soil, water, and agricultural products are well below 50 μg/kg in many parts of China. Yet in spite of such a decline, the current levels of pollution still pose a significant health risk to many people in China because OCPs are highly persistent and bioaccumulative substances. This preliminary study was conducted to monitor the levels of hexachlorocyclohexane (HCH) and dichloro-diphenyl-trichloroethane (DDT) in human and fish fats from southeast China in an effort to corroborate the above health concern. The data reconfirmed that pollution by HCH and DDT, which are the major components of OCPs, is a serious ecological problem in the study region, and likely in other parts of China as well. The HCH contents in the human samples were between 0.25 and 2.20 mg/kg, with an average of 0.90 mg/kg. The DDT contents in these human samples were much higher, between 0.54 and 9.22 mg/kg with an average of 3.50 mg/kg. The major isomers found in the human samples were β-HCH and p, p′-DDE, representing 94.9 to 99.5% of total HCH and 72.3 to 96.7% of total DDT, respectively. The HCH and DDT content in the grass carp samples averaged 0.03 and 0.67 mg/kg, respectively. The levels of bioaccumulation reflected in these human and fish samples were considered substantial, particularly when residents in the study region continue to be exposed to the OCPs remaining so persistently in their environment. It is therefore important for the health authorities to launch a large-scale investigation into the potential health and ecological impacts of OCP pollution in China. The data also suggested that the current national standards might need to be lowered for the levels of OCPs in the environment in China.     

重金属污染对鸟类的影响

鸟类属于高等脊椎动物，是食物链中的高级消费者，由于生物富集作用，鸟类容易受到环境中污染物质的影响。鸟类羽毛和卵壳中的重金属浓度可以反映其所处环境中重金属的污染状况，因此可以用鸟类作为指示生物来监测环境中的重金属污染。对重金属污染的来源和特征进行了介绍，阐述了重金属污染对环境安全构成威胁的原因，分析了汞、铅、镉、砷、铜等几种重金属元素在鸟体内富集的特点及其对鸟类的危害。重金属污染物在不同生物体内的浓度存在差异，反映出它们通过食物链的生物富集和放大，对环境和鸟类的毒害作用有所增加。建议选择野生鹭类、麻雀和喜鹊等鸟类作为指示生物监测环境中的重金属污染。