Toxic cyanobacteria and microcystin concentrations in a public water supply reservoir in the Brazilian Amazonia region.

Toxic cyanobacteria in public water supply reservoirs represent a serious health risk as they can release potent cyanotoxins into the water. In the present study we analyzed surface water collected from the Utinga Reservoir, the main source of drinking water for the city of Belem-PA, in order to characterize the reservoir's cyanobacterial biota and to determine the toxicity of these organisms and the concentration of microcystins in raw and treated water. The cyanobacterial biota included potentially toxic genera such as Aphanizomenon, Microcystis, Nostoc, Oscillatoria, Planktothrix and Radiocystis. Mouse bioassays revealed a 43.6% frequency of hepatotoxic strains, including 30.8% Microcystis viridis strains and 12.8% Radiocystis fernandoi strains, with the lowest LD(100) (ip) of 45 and 75 mg kg(-1) body weight, respectively. Subacute hepatotoxicity was observed for Aphanizomenon cf. gracile and Coelomoron pusillum strains. HPLC analysis confirmed the production of microcystins at maximum concentrations of 4.22 microg mg(-1) dry weight for M. viridis and 2.47 microg mg(-1) for R. fernandoi. Microcystins at concentrations of up to 1.25 microg L(-1) detected in raw water by ELISA, together with a cyanobacterial density of 20,000 cells mL(-1), represents the first report of a bloom of cyanobacteria for an Amazonian water body.     

Detection and quantification of microcystins from cyanobacteria strains isolated from reservoirs and ponds in Morocco

In Morocco, the occurrence of toxic cyanobacteria blooms is confirmed in some water bodies used for recreational and/or as drinking water reservoirs. According to WHO recommendations, the establishment of a monitoring program for microcystins is a necessity. This paper presents toxicological studies of 19 toxic cyanobacteria strains of Microcystis, Synechocystis, Pseudanabaena, and Oscillatoria. These strains were isolated from various water bodies including natural lakes, reservoirs, and ponds located in central regions of Morocco. The isolation, culture, and biomass production of these strains was made on Z8 or BG13 media under laboratory controlled conditions. The hepatotoxicity of cyanobacterial lyophilized material was confirmed by mouse bioassays. The amount of microcystins produced by each strain was determined by the enzyme-linked immunosorbent assay (ELISA). The detection and identification of microcystin variants was performed by high performance liquid chromatography (HPLC) with photodiode array detection. Almost all strains showed medium to high toxicity, the estimated LD50 i.p. mice bioassay ranged between 28 to 350 mg/kg body weight. The concentrations of microcystins varied between 2.16 to 944 micrograms/g and 26.8 to 1884 micrograms/g dry weight determined by ELISA and HPLC, respectively. The screening of bloom-forming and microcystin producer cyanobacteria strains in these fresh water bodies leads us to propose the need for the establishment of a survey of cyanobacteria and a cyanotoxin-monitoring program.     

Occurrence and elimination of cyanobacterial toxins in drinking water treatment plants

Toxin-producing cyanobacteria (blue-green algae) are abundant in surface waters used as drinking water resources. The toxicity of one group of these toxins, the microcystins, and their presence in surface waters used for drinking water production has prompted the World Health Organization (WHO) to publish a provisional guideline value of 1.0 mug microcystin (MC)-LR/l drinking water. To verify the efficiency of two different water treatment systems with respect to reduction of cyanobacterial toxins, the concentrations of MC in water samples from surface waters and their associated water treatment plants in Switzerland and Germany were investigated. Toxin concentrations in samples from drinking water treatment plants ranged from below 1.0 microg MC-LR equiv./l to more than 8.0 microg/l in raw water and were distinctly below 1.0 microg/l after treatment. In addition, data to the worldwide occurrence of cyanobacteria in raw and final water of water works and the corresponding guidelines for cyanobacterial toxins in drinking water worldwide are summarized.     

Sublethal exposure from microcystins to renal insufficiency patients in Rio de Janeiro, Brazil

In November 2001, a cyanobacterial bloom dominated by Microcystis and Anabaena occurred in the Funil Reservoir and the Guandu River, both of which supply drinking water to Rio de Janeiro, Brazil. Using ELISA, microcystins were detected at a concentration of 0.4 microg/L in the drinking water, whereas a concentration of 0.32 microg/L was detected in activated carbon column-treated water for use at the renal dialysis center of Clementino Fraga Filho Hospital (HUCFF) at the Federal University of Rio de Janeiro. A total of 44 hemodialysis patients who received care at this center were believed to be exposed. Initial ELISA analyses confirmed the presence of serum microcystin concentrations > or = 0.16 ng/mL in 90% of serum samples collected from these patients. Twelve patients were selected for continued monitoring over the following 2-month period. Serum microcystin concentrations ranged from < 0.16 to 0.96 ng/mL during the 57 days after documented exposure. ELISA-positive samples were found throughout the monitoring period, with the highest values detected 1 month after initial exposure. ESI LC/MS analyses indicated microcystins in the serum; however, MS/MS fragmentation patterns typical of microcystins were not identified. LC/MS analyses of MMPB for control serum spiked with MCYST-LR. and patient sera revealed a peak at retention time of 8.4 min and a mass of 207 m/z. These peaks are equivalent to the peak observed in the MMPB standard analysis. Taken together ELISA, LC/MS, and MMPB results indicate that these renal dialysis patients were exposed to microcystins. This documents another incident of human microcystin exposure during hemodialysis treatment.     

Identification of microcystins in waters used for daily life by people who live on Tai Lake during a serious cyanobacteria dominated bloom with risk analysis to human health

Tai Lake is the third largest freshwater lake in China with annual cyanobacteria blooms. Microcystins produced by these blooms have serious health risks for populations surrounding the lake, especially for people living on Tai Lake, because they usually drink raw lake water after a simple alum treatment. This study presents data on the detection and identification of microcystins in waters used for daily life by people living on Tai Lake, during the cyanobacterial blooming in July 2007. The health risks from drinking these microcystin-polluted waters were also calculated. The main microcystins detected by high-performance liquid chromatography-electrospray ionization mass spectrometry in the water samples collected from two parts of Tai Lake (Wuli Lake and Meiliang Bay) were MC-LR (4.33-12.27 microg/L), MC-RR (8.36-16.91 microg/L) and MC-YR (1.41-5.57 microg/L). Risk assessment showed that the drinking water simply treated by alum was not safe. The lowest calculated hazards ratios in all water samples was 6.4, which indicated that the risk of microcystins exposure from drinking water was over six times higher than the tolerable daily intake (TDI) recommended by The World Health Organization (WHO). Further studies should be conducted to elucidate the relationships between the epidemiology of people living on Tai Lake and microcystins exposure from drinking water.     

Microcystin Contamination and Toxicity: Implications for Agriculture and Public Health

Microcystins are natural hepatotoxic metabolites secreted by cyanobacteria in aquatic ecosystems. When present at elevated concentrations, microcystins can affect water quality aesthetics; contaminate drinking water reservoirs and recreational waters; disrupt normal ecosystem functioning; and cause health hazards to animals, plants, and humans. Animal and human exposures to microcystins generally result from ingesting contaminated drinking water or physically contacting tainted water. Much research has identified a multitude of liver problems from oral exposure to microcystins, varying from hepatocellular damage to primary liver cancer. Provisional guidelines for microcystins in drinking and recreational water have been established to prevent toxic exposures and protect public health. With increasing occurrences of eutrophication in freshwater systems, microcystin contamination in groundwater and surface waters is growing, posing threats to aquatic and terrestrial plants and agricultural soils used for crop production. These microcystins are often transferred to crops via irrigation with local sources of water, such as bloom-forming lakes and ponds. Microcystins can survive in high quantities in various parts of plants (roots, stems, and leaves) due to their high chemical stability and low molecular weight, increasing health risks for consumers of agricultural products. Studies have indicated potential health risks associated with contaminated fruits and vegetables sourced from irrigated water containing microcystins. This review considers the exposure risk to humans, plants, and the environment due to the presence of microcystins in local water reservoirs used for drinking and irrigation. Additional studies are needed to understand the specific health impacts associated with the consumption of microcystin-contaminated agricultural plants.     

Cyanobacteria and their toxins in treated-water storage reservoirs in Abha city, Saudi Arabia.

Occurrence of toxic cyanobacteria in drinking and recreational waters poses human health at risk as they can release potent toxins into the water. In the present study, open and covered treated-water storage reservoirs as well as their relevant tap waters in Abha city, Saudi Arabia, were surveyed for the presence of cyanobacteria and their toxins. The results revealed the contamination of most open reservoir and tap waters by algae and cyanobacteria, with an abundance of toxigenic species of cyanobacteria. Depending on the results of the Limulus amebocyte lysate (LAL) assay and enzyme linked immunosorbent assay (ELISA), endotoxins and microcystins (MCYSTs) were found in most open reservoir and tap waters at concentrations up to 32EUml(-1) and 0.3mugml(-1), respectively. The extracts of axenic cultures of most cyanobacterial species isolated from these reservoirs showed activity to LAL assay, with large endotoxin amounts obtained in Calothrix parietina (490EUg(-1)) and Phormidium tenue (210EUg(-1)). Based on ELISA and HPLC analysis for these extracts, only C. parietina can produce MCYSTs (202mugg(-1)) with a profile consisting of MCYST-RR and -LR. This study suggests that open treated-water storage reservoirs should be covered to prevent the presence of cyanobacteria and their toxins in such drinking and recreational waters.     

Occurrence of toxic cyanobacterial blooms in San Roque Reservoir (Córdoba,Argentina): a field and chemometric study

We evaluated the presence of cyanobacterial blooms in San Roque Reservoir (Córdoba, Argentina). Cyanobacterial blooms and water samples were collected over 4 years (1998-2002). We confirmed the presence of microcystin-LR and microcystin-RR in 97% of these blooms. The total amount of microcystin (MC) ranged between 5.8 and 2400.0 microg x g(-1) of freeze-dried bloom material. These values suggest that guidelines for safe water consumption and recreational use should be established for this reservoir. Twenty-eight physical and chemical parameters were measured in water samples and evaluated by discriminant analysis (DA). A first DA was used to evaluate the factors promoting cyanobacteria occurrence, identifying nine parameters following three patterns associated with cyanobacterial growth. Inorganic phosphorous was found to promote the presence of blooms, whereas the highest proliferation of cyanobacteria was observed in the presence of smaller amounts of carbonate, bicarbonate, sulfate, and fecal coliform bacteria. The results observed during our fieldwork, analyzed using DA, agreed with the results of other laboratory studies, thus confirming the usefulness of DA to help with the evaluation of a complicated environmental data matrix. A second DA, using only water samples collected during the presence of cyanobacteria blooms, identified another nine parameters. The analysis of these parameters allowed us to identify certain environmental factors that could lead to the dominance of toxic strains, thus increasing the amount of MC. The results showed that, in our case, an increase in the water temperature was associated with higher amounts of MC per dry weight unit, whereas an increase in the concentrations of ammonia-nitrogen and iron were associated with lower amounts of MC, thus disfavoring the dominance of toxic strains.     

Occurrence and elimination of cyanobacterial toxins in two Australian drinking water treatment plants.

In Australian freshwaters, Anabaena circinalis, Microcystis spp. and Cylindrospermopsis raciborskii are the dominant toxic cyanobacteria. Many of these surface waters are used as drinking water resources. Therefore, the National Health and Medical Research Council of Australia set a guideline for MC-LR toxicity equivalents of 1.3 microg/l drinking water. However, due to lack of adequate data, no guideline values for paralytic shellfish poisons (PSPs) (e.g. saxitoxins) or cylindrospermopsin (CYN) have been set. In this spot check, the concentration of microcystins (MCs), PSPs and CYN were determined by ADDA-ELISA, cPPA, HPLC-DAD and/or HPLC-MS/MS, respectively, in two water treatment plants in Queensland/Australia and compared to phytoplankton data collected by Queensland Health, Brisbane. Depending on the predominant cyanobacterial species in a bloom, concentrations of up to 8.0, 17.0 and 1.3 microg/l were found for MCs, PSPs and CYN, respectively. However, only traces (<1.0 microg/l) of these toxins were detected in final water (final product of the drinking water treatment plant) and tap water (household sample). Despite the low concentrations of toxins detected in drinking water, a further reduction of cyanobacterial toxins is recommended to guarantee public safety.     

Microcystin contamination in fish from the Jacarepaguá Lagoon (Rio de Janeiro, Brazil): ecological implication and human health risk.

Chronic and subchronic toxicity from exposure to microcystins, cyclic peptide liver toxins from certain cyanobacteria, poses an important hazard, which has received little study. No in vivo information exists on accumulation and transfer of microcystin from the food chain to humans. This paper present results of a 3-year study that demonstrates bioaccumulation of microcystins by fish and potential rates of microcystin ingestion by humans. The study was carried out in a shallow coastal lagoon in the city of Rio de Janeiro (Jacarepaguá Lagoon). Fish (Tilapia rendalli) were collected every 2 weeks from August 1996 to November 1999. Microcystins were analyzed by HPLC in phytoplankton, fish liver and viscera while fish muscle tissue was analyzed by enzyme linked immunosorbant assay (ELISA). Phytoplankton samples, dominated by the genus Microcystis, were confirmed to contain microcystins as were fish livers, viscera and muscle tissue. During the entire study period, including times of low water bloom densities, fish muscle tissue contained concentrations of microcystins close to or above the recommended limit for human consumption (0.04 microg x kg(-1) day). Our findings demonstrate that microcystins can accumulate in fish tissue used for human consumption. Rates of ingestion routinely exceed the TDI guidelines as set by the WHO for drinking water. Appropriate epidemiology and risk assessment should be undertaken so that an acceptable TDI and appropriate risk management decisions can be made for human consumption of fish which are harvested from cyanobacterial blooms that contain cyanotoxins.     

Detection and monitoring toxigenicity of cyanobacteria by application of molecular methods

The aim of this study was early genetic identification of microcystin-producing cyanobacteria and monitoring their toxigenicity by determining toxin concentrations in three Polish lakes throughout the summer of 2004. The assessment of cyanobacterial blooms was carried out in shallow, eutrophic water bodies: Lake Jeziorak, Lake Bninskie, and Sulejow Reservoir. Samples for DNA, phycological, and toxin analyses were collected from July till October. Molecular analysis of the 16S rRNA region was used to detect cyanobacteria in water samples. The microscopic analysis was performed to investigate seasonal variation of phytoplankton. Cyanobacteria, with domination by Microcystis, Planktothrix, and Planktolyngbya were detected during the whole monitoring period in Sulejow Reservoir, Lake Bninskie, and Lake Jeziorak, respectively. The presence and identification of toxic strains in water bodies was studied by PCR amplification of mcy genes in the microcystis synthesis pathway. The presence of the mcyA, mcyB, mcyD, and mcyE genes in water samples indicated the genetic potential to produce microcystins. Toxicity of water samples and microcystin concentrations were established by PPIA and HPLC, respectively. The maximum concentration of microcystins was 11.13 microg/L and 4.67 microg/L in samples dominated by P. agardhii and M. aeruginosa, respectively. Molecular analysis showed that toxigenic strains of cyanobacteria occurred in the three lakes throughout the summer season.     

Intracellular and dissolved microcystin in reservoirs of the river Segura basin, Murcia, SE Spain.

The seasonal sampling of irrigation or drinking water reservoirs in the province of Murcia (SE Spain) in the hydrological year 2000-2001 revealed the presence of intracellular microcystins in the benthic cyanophyte communities throughout the year. The total microcystin levels, as measured by HPLC, were relatively high but lower than others published for planktonic communities of the European continent or certain African countries. The diversity of forms was also very high and comparable to those found for other European countries. The concentrations of microcystins dissolved in the water were always below limits recommended by the WHO for drinking water and, during most of the year, undetectable by immunological methods. We discuss the need for setting up a control network for detecting benthic cyanobacteria growth to prevent long-term undesirable effects in the human population in small towns (through drinking water or the consumption of vegetables) and in wild animals. In the particular case of the Iberian Peninsula, a joint strategy between Portugal and Spain is recommendable.     

Genotoxicity of cyanobacterial extracts containing microcystins from Polish water reservoirs as determined by SOS chromotest and comet assay

Toxicity of cyanobacterial blooms, an increasing problem around the world, is connected to the increase in bloom samples containing microcystins, caused by excessive eutrophication of drinking- and recreational water reservoirs. Microcystins are the most common group of cyanobacterial hepatotoxins. In Poland they are produced mainly by the Microcystis genus. The toxicity of microcystins has been well documented, but investigation into their genotoxicity has been insufficient relative to the study of their overall toxicity. Therefore, the aim of this study was the estimation and comparison of the genotoxicity of cyanobacterial extracts with microcystins (CEMs) using the SOS chromotest (bacterial test) with Escherichia coli PQ37 and the comet assay with human lymphocytes. Cyanobacterial bloom samples were collected in the summer months from two Polish water reservoirs, one at Sulejów and one at Jeziorsko. The SOS chromotest, which used prokaryotic cells (without metabolic activation), and the comet assay, which used eukaryotic cells, both indicated the potential genotoxic effect of CEMs. Cyanobacterial extracts caused DNA damage in human lymphocytes in vitro. The maximum level of DNA damage was observed after 12 h incubation with CEMs. The bacterial test indicated a dependence of the degree of CEM genotoxicity, the composition, and the concentration of microcystins in each bloom sample examined with the time of exposure. Differences between the genotoxicity of cyanobacterial extract and the standard microcystin-LR were noticeable. This was probably caused by the interaction of different microcystin variants. The results showed that CEMs from Polish water reservoirs were genotoxic, which was reflected by the stimulation of the SOS repair system in bacterial cells (SOS chromotest) and by the damage induced in DNA in human lymphocytes (comet assay).     

The use of Lepidium sativum in a plant bioassay system for the detection of microcystin-LR.

Toxin-producing cyanobacteria pose a worldwide health threat to humans and animals due to their increasing presence in both drinking and recreational waters. Detection of microcystins in water generally relies on specialised equipment and a delay of several days for transport and analysis. Little work has, however, been done on establishing a simple, cost-effective and sensitive plant bioassay for the detection of microcystin-LR (MCLR) in water at the WHO Tolerable Daily Intake guideline level of 1 microg/l. We investigated the effect of a MCLR extract at 1 and 10 microg/l on the growth of Lepidium sativum over 6 days. Exposure to 10 microg/l MCLR resulted in a significant decrease in root and leaf lengths and fresh weights of seedlings when compared to the controls. These results were consistent with seedlings exposed to pure MCLR at 10 microg/l. Seedlings exposed to 1 microg/l MCLR showed a significant decrease in root development from day 2 to day 6. Glutathione S-transferase and glutathione peroxidase activities were also significantly raised in plants from days 5 and 4, respectively, at both toxin levels investigated.     

A colorimetric and fluorometric microplate assay for the detection of microcystin-LR in drinking water without preconcentration.

Protein phosphatase inhibition assays currently used for the detection of cyanobacterial peptide hepatotoxins in drinking water require an enrichment step using C18 cartridges to achieve lower the detection limit. This paper describes a colorimetric and fluorometric protein phosphatase inhibition method for the direct detection of microcystin-LR (MCYST-LR) in drinking water without complex clean-up steps and preconcentration procedures. In this assay three different substrates, p-nitrophenyl phosphate (p-NPP) and two fluorogenic compounds, 4-methylumbelliferyl phosphate (MUP) and 6,8-difluoro-4-methylumbelliferyl phosphate DiFMUP), were tested. The detection limits of the assay are 0.25 and 0.1 microg/l using colorimetric and fluorometric methods, respectively. These levels are well below the provisional guideline value for MCYST-LR of 1 microg/l of drinking water. The detection limit of the fluorometric method is comparable to that of the classical ELISA test. Although both the latter tests allow the detection of MCYST-LR in drinking water directly without pretreatment, the protein phosphatase inhibition assay remain less expensive and therefore more attractive for use in the routine assessment of drinking water contamination by microcystins.     

Microcystins (cyanobacteria hepatotoxins) bioaccumulation in fish and crustaceans from Sepetiba Bay (Brasil, RJ).

Blooms of cyanobacteria in water bodies cause serious environmental problems and the occurrence of toxic strains are also related with the human health. Aquatic animals could bioaccumulate microcystins (cyanobacteria hepatotoxins) and so, beyond water, the ingestion of contaminated food represents a human health risk. Recently, WHO recommended a maximum concentration of microcystins (MCYSTs) in drinking water and established the tolerable daily intake (TDI) for consumption of cyanobacteria products contends MCYSTs (0.04 microg(-1) kg(-1) day(-1)). Sepetiba Bay is located in the municipal districts of Rio de Janeiro, Mangaratiba and Itaguai; being an important place of fishing activity. Due to the industrial development in the area, this bay is submitted to different environmental impacts, increasing the organic and industrial pollution. A strain of the nanoplanktonic cyanobacteria Synechocystis aquatilis f. aquatilis that produce MCYSTs was already isolated. In this study, we verified MCYSTs presence in muscle tissue of fish and crustaceans, which were harvested monthly in Sepetiba Bay during 11 months, in order to evaluate the potential risk of their ingestion. MCYSTs were analyzed by immunoassay techniques using the ELISA Microcystin Plate Kit (ENVIROLOGIX INC) and the concentration were expressed as microcystin-LR equivalent. The analyses of seston samples, water, muscle tissues showed the presence of this cyanotoxin in all samples and it was verified that 19% of the animals' samples were above the limit recommended by WHO for human consumption. The maximum value found was of 103.3 microg kg(-1) (TDI 0.52 microg kg(-1) day(-1)) and the minimum, was 0.25 microg kg(-1) in crabs muscle tissue (TDI of 0.001 microg kg(-1) day(-1)). Such data demonstrate that, although in low concentrations, there is already a contamination of fish and crustaceans from Sepetiba Bay. We highlight that the recommended limit refers to healthy adult.     

The adsorption of microcystin-LR by natural clay particles.

The microcystin cyanobacterial hepatotoxins represent an increasingly severe global health hazard. Since microcystins are found world wide in drinking water reservoirs concern about the impact on human health has prompted investigations into remedial water treatment methods. This preliminary study investigates the scavenging from water of microcystin-LR by fine-grained particles known to have a high concentration of the clay minerals kaolinite and montmorillonite. The results show that more than 81% of microcystin-LR can be removed from water by clay material. Thus, microcystin-LR is indeed scavenged from water bodies by fine-grained particles and that this property may offer an effective method of stripping these toxins from drinking water supplies.     

A new morphospecies of Microcystis sp. forming bloom in the Cheffia dam (Algeria): seasonal variation of microcystin concentrations in raw water and their removal in a full-scale treatment plant

Toxic cyanobacterial blooms are an increasing problem in Algeria. The production of cyanotoxins (microcystins) and their presence in drinking water represent growing hazards to human health. In this study, seasonal variations in the concentrations of total microcystins and physicochemical parameters (pH, temperature, dissolved oxygen, nitrate, orthophosphate, and chlorophyll-a) were analyzed in the Cheffia dam (Algeria), mainly used to supply drinking water. The removal of cyanobacterial cells and microcystins was also evaluated in full-scale plant associated with the Cheffia reservoir. The levels of microcystins (MCYSTs) in both raw and drinking water were evaluated using the protein phosphatase type 2A (PP2A) inhibition test as MCYST-LR equivalents. Identification of microcystin variants was achieved by LC/MS/MS. During the period of study (March-December 2004), microscopic observation showed the dominance in the autumn months (September-November) of a new morphospecies of Microcystis sp. The MCYST-LR equivalent concentrations in raw water varied between 50.8 and 28,886 ng L(-1). The highest level of toxins was observed in October 2004 and was significantly correlated with the chlorophyll-a. Three variants of microcystins assigned as microcystin-YR (MCYST-YR), microcystin-LR (MCYST-LR), and 6Z-Adda stereoisomer of MCYST-LR were observed in the crude extract of the Microcystis sp. bloom sample. During the bloom period, total elimination of Microcystis sp. and toxins were achieved through a classical treatment plant comprised of coagulation and flocculation, powdered activated carbon at 15 mg L(-1), slow sand filtration and chlorination before storage.     

Recreational exposure to microcystins during algal blooms in two California lakes

We conducted a study of recreational exposure to microcystins among 81 children and adults planning recreational activities on either of three California reservoirs, two with significant, ongoing blooms of toxin-producing cyanobacteria, including Microcystis aeruginosa (Bloom Lakes), and one without a toxin-producing algal bloom (Control Lake). We analyzed water samples for algal taxonomy, microcystin concentrations, and potential respiratory viruses (adenoviruses and enteroviruses). We measured microcystins in personal air samples, nasal swabs, and blood samples. We interviewed study participants for demographic and health symptoms information. We found highly variable microcystin concentrations in Bloom Lakes (<10 μg/L to >500 μg/L); microcystin was not detected in the Control Lake. We did not detect adenoviruses or enteroviruses in any of the lakes. Low microcystin concentrations were found in personal air samples (<0.1 ng/m³ [limit of detection]-2.89 ng/m³) and nasal swabs (<0.1 ng [limit of detection]-5 ng). Microcystin concentrations in the water-soluble fraction of all plasma samples were below the limit of detection (1.0 μg/L). Our findings indicate that recreational activities in water bodies that experience toxin-producing cyanobacterial blooms can generate aerosolized cyanotoxins, making inhalation a potential route of exposure. Future studies should include collecting nasal swabs to assess upper respiratory tract deposition of toxin-containing aerosols droplets.     

Toxic cyanobacterial blooms in reservoirs under a semiarid mediterranean climate: the magnification of a problem

Sicilian reservoirs constitute the most important water resources available on the island. During summer 2001, the intense water utilization of Lake Arancio reservoir reduced the water level significantly, which coincided with the formation of intense blooms formed by the microcystin (MC)-producing cyanobacterium Microcystis aeruginosa. During summer 2003, Lake Arancio was continuously filled and the vertical stratification of the water column was maintained resulting in five to sixfold lower cell numbers of M. aeruginosa. For both years, a significant relationship between MC net production and Microcysytis cell growth was observed, implying that Microcystis cell numbers can be used to infer MC concentrations in water. Unexpectedly, dense blooms of the MC-producing cyanobacterium Planktothrix rubescens occurred during winter 2005/2006 in the reservoirs Lake Pozzillo, Prizzi, Nicoletti, and Garcia but have not been reported earlier. In this season, MC concentrations higher than those recorded in summer were measured, implying that monitoring of Mediterranean drinking water reservoirs needs to be intensified during winter, a season usually considered to be less prone to the formation of cyanobacterial blooms.