Size Distribution of Aerosols (PM10) and Lead (Pb) near Traffic Intersections in Mumbai (India)

The size distribution of aerosols was measured near traffic intersections of Marol link road in air quality control region (AQCR1), which is a moderately industrial area and Dadar Khodad circle in AQCR2, which is a heavily commercial core of the Mumbai City. The reason behind selecting the two unidentical regions was to study the contribution from vehicles to the size separated PM10 and that of Pb. It is recognised that particulates in urban air are responsible for serious health effects. As very small particles are assumed to be important for the adverse health effects, the particle size distribution is thus an important factor that needs to be addressed whenever the particulates pollution is concerned. The size measurements were done with a cascade impactor of eight stages with a back-up filter. It effectively separates the particulate matter into nine-sizes ranging from 0.0-0.4 to 9.0-10.0 microm. Samples were analysed in nine-particle size fractions with special reference to a toxic metal - lead (Pb) by atomic absorption spectrophotometry (AAS). It was found that PM10 and Pb at both the intersections could easily be classified by the size distribution. The fractions of the PM10 and that of Pb showing a tendency of trimodal distributions with the first peak at coarse mode approximately 9.0-10.0 microm, second at approximately 5.8 microm and the third at coarse mode approximately1.1 microm. The significant percentage of Pb was found in the range below 2.5 microm at both the intersections. However, Pb in AQCR1 is found in the coarser range as well, which could probably be the influence of various industrial activities in the area. PM10 concentration values in the coarser range in AQCR2 are associated with the resuspension of dust particles and mechanical erosions.     

A regional survey of malformed frogs in Minnesota (USA) (Minnesota malformed frogs)

In late 1995, school children discovered malformedfrogs in a south central Minnesota pond. Press coverage resultedin numerous citizen reports of frog malformation across Minnesotain 1996. After some initial site investigation, 3 affected frogsites and 4 nearby reference sites were selected for moredetailed evaluation. Field biologists made 89 visits to studysites beginning spring 1997 through fall 1999 to examine thenumber and type of frog malformations. Over 5,100 Leopardfrogs (Rana pipiens) were captured and examined atall study sites. Water elevations and associated littoralinundation were recorded from 1997-2000. Results indicate thatmalformation occurred at all study sites above historicalbackground levels. Rana pipiens malformation across allsites over three seasons averaged 7.9% and ranged from 0 to 7% at reference sites and 4 to 23% at affected sites. At onenorthern Minnesota site, mink frog (Ranaseptentrionalis) malformation was 75% in 1998. A sitecharacteristic common to the most affected sites was an elasticzone of littoral inundation. Climate driven hydrologic variationlikely influenced water depth and associated breeding locations.     

Lead (Pb) and arsenic (As) bioaccessibility in various soils from south China

Serious problems are faced in several parts of the world due to the presence of high concentration of fluoride in drinking water which causes dental and skeletal fluorosis to humans. Nalgonda district in Andhra Pradesh, India is one such region where high concentration of fluoride is present in groundwater. Since there are no major studies in the recent past, the present study was carried out to understand the present status of groundwater quality in Nalgonda and also to assess the possible causes for high concentration of fluoride in groundwater. Samples from 45 wells were collected once every 2 months and analyzed for fluoride concentration using an ion chromatograph. The fluoride concentration in groundwater of this region ranged from 0.1 to 8.8 mg/l with a mean of 1.3 mg/l. About 52% of the samples collected were suitable for human consumption. However, 18% of the samples were having less than the required limit of 0.6 mg/l, and 30% of the samples possessed high concentration of fluoride, i.e., above 1.5 mg/l. Weathering of rocks and evaporation of groundwater are responsible for high fluoride concentration in groundwater of this area apart from anthropogenic activities including irrigation which accelerates weathering of rocks.     

Residual fate and persistence of endosulfan (50 WDG) in Bengal gram (Cicer arietinum)

A detailed study has been presented on heavy metal content of the Iture Estuary. Waters of the Sorowie and Kakum rivers that supply water into the Estuary were investigated to ascertain heavy metal pollution levels due to anthropogenic activities. Concentration s of Cd, Zn, Se and Pb were measured. The study shows pre-occupying pollution levels that constitute a threat to both terrestrial and aquatic ecosystems. The abundance of metals in the Estuary is in the order Zn > Pb > Cd > Se. The level of Cd in the Iture Estuary ranged between 0.011 mg/l and 0.041 mg/l while Se was in the range 0.018 mg/l to 0.029 mg/l, Pb 0.020 mg/l to 0.075 mg/l and Zn 0.040 to 2.45 mg/l. The impact of contaminated water from the Sorowie River on the Iture Estuary was outstanding and the study points out the importance of the Sorowie River as a primary pollution source to the Iture Estuary. The pollution of the Iture Estuary was found to be connected to human activities in its catchments.     

Essential (Cu) and nonessential (Cd and Pb) metals in ichthyofauna from the coasts of Sinaloa state (SE Gulf of California)

With the aim of giving an overview on concentration and distribution of Cd, Cu, and Pb in fish from the coasts of Sinaloa state (SE Gulf of California), specimens with different feeding habits were collected in five locations. Sampling occurred between June 2003 and March 2004. Metal analyses on fish tissues were made by graphite furnace (Cd, Pb) and flame (Cu) atomic absorption spectrophotometry. Metal concentrations in tissues of carnivorous fish were grouped together and compared with corresponding concentrations in non-carnivorous fish; Cu and Pb levels were significantly (p?<?0.05) higher in liver of non-carnivorous species. Though no samples exceeded the maximum level set in international legislation for fish, from the perspective of the public health and considering the legal limits of fishery products for human consumption, Cu concentrations were exceeded (in tissues different from muscle) in four carnivorous and five non-carnivorous species according to the Australian legislation. In the case of Cd, two carnivorous species (Pomadasys leuciscus and Caulolatilus princeps) and one non-carnivorous species (Mugil cephalus), showed concentrations over the maximum level of 2 μg g^???1 dry weight considered in the Mexican legislation. Considering average amounts of fish consumption in Mexico, daily mineral intake (DMI) values for Cu and percentage weekly intake (PWI) of Cd and Pb were estimated; none of the analyzed metals in edible portion of analyzed fish could be detrimental to humans.     

电感耦合等离子体质谱法测定饮用水中的硒

应用电感耦合等离子体质谱法测定饮用水中的硒元素。结果表明,高能碰撞模式(HEHe)较碰撞/反应池气体模式(He模式)消除干扰效果更好;在HEHe模式下,~(78)Se在0.5~100μg/L范围内线性良好,相关系数0.999 9,方法检出限为0.06μg/L,相对标准偏差为0.4%~0.8%,加标回收率为97.1%~103.2%。方法性能指标均能较好满足饮用水中Se的定量测试要求。     

Occurrence of haloacetic acids (HAAs) and trihalomethanes (THMs) in drinking water of Taiwan

In this study, water samples were collected from 86 water treatment plants for analysis of haloacetic acids (HAAs) and trihalomethanes (THMs) from February to March, 2007 and from July to August, 2007. Both seasonal and geographical variations of disinfection by-products (DBPs) in drinking water of Taiwan were presented. The results showed that the five HAA concentrations (HAA5) were 1.0–38.9 μg/L in the winter and 0.2–46.7 μg/L in the summer; and the total THMs were ND-99.4 μg/L in the winter and ND-133.2 μg/L in the summer. For samples taken from the main Taiwan island, dichloroacetic acid (29.4–31.7%) and trichloroacetic acid (25.3–27.6%) were the two major HAA species, and trichloromethane was the major THM species (49.9–62.2%) in finished water. For water treatment plants located on the offshore islands outside of Taiwan, high bromide concentration was found in raw water, and higher percentage of brominated THMs and HAAs were formed in the overall formation. A statistically significant (P?<?0.005) logarithmic linear regression model was found to be useful to describe the correlations between TTHM and HAA5 or nine HAAs (HAA5?=?1.219 ×TTHM ^0.754, R ²?=?0.658; HAA9?=?1.824 ×TTHM ^0.735, R ²?=?0.678). No apparent difference was observed for DBPs concentrations between finished water and distribution samples in this study.     

Speciation of As(III) and As(V) in water and sediment using reverse-phase ion-pair high-performance liquid chromatography-neutron activation analysis (HPLC-NAA)

Total As content and the As species distribution in water and sediments from the Kwabrafo stream, a major water body draining the Obuasi gold mining community in southwestern Ghana, have been investigated. Total As content was determined by instrumental neutron activation analysis (INAA). Ion-pair reverse phase high-performance liquid chromatography-neutron activation analysis (HPLC-NAA) was used for speciation of As species. Solid phase extraction with phosphate buffer was used to extract soluble As species from lyophilized sediment. The mass balance after phosphate extraction of soluble As species in sediment varied from 89 to 96 %. Compositionally appropriate reference material International Atomic Energy Agency (IAEA)-Lake Sediment (SL)-1 was used to check the validity of INAA method for total As determination. The measured values are in good agreement with the IAEA recommended value and also within the 95 % confidence interval. The accuracy of the measurement in terms of relative deviation from the IAEA recommended value was ±0.83 %. “In-house” prepared As(III) and As(V) standards were used to validate the HPLC-INAA method used for the As species determination. Total As concentration in the water samples ranged from 1.15 to 9.20 mg/L. As(III) species in water varied from 0.13 to 0.7 mg/L, while As(V) species varied from 0.79 to 3.85 mg/L. Total As content in sediment ranged from 2,134 to 3,596 mg/kg dry mass. The levels of As(III) and As(V) species in the sediment ranges from 138 to 506 mg/kg dry mass and 156 to 385 mg/kg dry mass, respectively.     

Occurrence of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Lake Maggiore (Italy and Switzerland)

Samples of air (gas and particulate phases), bulk deposition, aquatic settling material and sediments were collected in Lake Maggiore (LM) in order to determine their content of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). Air (gas and particulate phases) concentrations were 0.5 pg m(-3), 80 pg m(-3), 13 pg m(-3) and 106 pg m(-3) for SigmaPCDD/Fs, SigmaPCBs, Sigma dioxin-like PCBs (DL-PCBs) and SigmaPBDEs, respectively. Deposition fluxes ranged from 0.7 ng m(-2) d(-1) for SigmaPCDD/Fs to 32 ng m(-2) d(-1) for SigmaPCBs. Aquatic settling material presented concentrations of 0.4 ng g(-1) dry weight (dw) for SigmaPCDD/Fs, 13 ng g(-1) dw for SigmaPCB, 3.4 ng g(-1) dw for SigmaDL-PCBs and 5.7 ng g(-1) dw for SigmaPBDEs. Mean sediment concentrations were 0.4 ng g(-1) dw for SigmaPCDD/Fs, 11 ng g(-1) dw for SigmaPCB, 3 ng g(-1) dw for SigmaDL-PCBs and 5.1 ng g(-1) dw for SigmaPBDEs. Similar PCDD/F and DL-PCB congener patterns in all the environmental compartments of LM point to an important, if not dominant, contribution of atmospheric deposition as source of these pollutants into LM. In contrast, PBDE congener distribution was not similar in the different environmental compartments. BDE 47 dominated air and settling material, while BDE 209 was the predominant congener in the bulk atmospheric deposition. Moreover, sediments showed two distinct PBDE congener profiles. Lower PBDE concentrated sediments were dominated by congeners 47 and 99, while BDE 209 dominated in higher PBDE concentrated samples. This suggests the influence of local sources as well as atmospheric input of PBDEs into LM.     

Airborne endotoxin in woodworking (joinery) shops

Symptoms such as shortness of breath and cough have been noted in woodworking facilities even where wood dust itself is well-controlled. Suspicion has fallen on other possible contaminants in the workplace atmosphere, including bacterial endotoxin. A few studies have indicated potentially high endotoxin exposure with exposure to fresh wood in sawmills and in the production of fiberboard and chipboard, but fewer studies have been carried out on exposure to endotoxin in dry wood work, for example in joineries. A study of the endotoxin content of airborne wood dust samples from US woodworking facilities is presented, from the re-analysis of samples which previously had been taken to establish mass collection relationships between the IOM sampler, the closed-face 37 mm plastic cassette (CFC) sampler and the Button sampler. Endotoxin was strongly correlated with total dust, but the endotoxin content of a few fresh wood samples was found to be up to ten times higher per unit of wood dust than for dried-wood samples, and this difference was significant. No long-term time-weighted average sample exceeded the recommended limit value of 50 EU m(-3) (EU, endotoxin units)used in the Netherlands, although a number of the IOM samples came close (seven samples or 44% exceeded 20 EU m(-3)) and one short-term (48 minute) sample registered a high value of 73 EU m(-3). The geometric mean concentration from the IOM samples (11 EU m(-3)) is within the range of geometric means found from Australian joineries (3.7-60, combined: 24 EU m(-3)). In contrast, the corresponding values from the CFC (3.6 EU m(-3)), and the Button sampler (2.1 EU m(-3)) were much lower and no samples exceeded 20 EU m(-3). Endotoxin is likely only to be a significant problem in working with dried woods when associated with very high dust levels, where the wood dust itself is likely to be a cause for concern. The results from the few samples in this study where fresh wood was being worked were similar to results from other studies involving fresh woods. The agreement between these studies is encouraging given the difficulties of endotoxin analysis and the wide variation often expected between different laboratories.     

Poly(sodium acrylamidoalkanoates) in water treatment

Poly(sodium 6-acrylamidocaproate), poly(sodium 11-acrylamidoundecanoate), poly(sodium 11-N-methylacrylamidoundecanoate) and poly(sodium 11-N-ethylacrylamidoundecanoate) have been synthesized. The performance of these anionic polyelectrolytes as coagulant aids in water treatment was assessed by the jar test. The effects of polymer dosage and pH on their performances were investigated in order to establish the optimum flocculation conditions. The effectiveness of these polyelectrolytes as well as a commercially available cationic polyamine organic coagulant aid was compared in terms of floc size, settling rate and the quality of treated water. Poly(sodium 6-acrylamidocaproate) and poly(sodium 11-acrylamidoundecanoate) were superior to poly(sodium 11-N-methylacrylamidoundecanoate) and poly(sodium 11-N-ethylacrylamidoundecanoate), and they are as effective as the commercial cationic coagulant aid.     

Determination of N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) in the general population using gas chromatography-mass spectrometry

Carbamoylation of glutathione, peptides and DNA is thought to be one of the most important reactions occurring in an organism after exposure to nitrosoureas, methylformamides or isocyanates. The carcinogenic effects of carbamoylation are not yet fully clarified. Although carbamoylation is known to occur after occupational exposure, it has never been reported in the general population. To clarify the situation, we investigated the levels of N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) in urine samples from persons without occupational exposure using a sensitive and specific method (gas chromatography-mass spectrometry, GC-MS). AMCC is the degradation product of N-methylcarbamoylated glutathione. The clean-up procedure of urine samples includes two liquid-liquid extraction steps and solid phase extraction using a cation-exchange resin to separate AMCC from other urinary components. N,N-Dimethylpropionic acid amide (DMPA) is used as internal standard. During the preparation of the samples, AMCC is converted to ethyl-N-methylcarbamate (EMC) in the presence of anhydrous potassium carbonate (K2CO3) and ethanol. The reliability and accuracy of this method have been proven in detail. The relative standard deviation for the within-series imprecision for three different concentrations was determined to be between 10.9% and 14.3%, while the relative standard deviation for the between-day imprecision was between 11.3% and 14.8%. The mean recovery for AMCC was determined to be between 79.2% and 85.6%. The limit of detection for the simultaneous measurement of two fragment masses was 30 micrograms L-1. Using this GC-MS method, we analysed urine samples from 42 individuals of the general population in order to determine their urinary excretion of AMCC. It was identified in 40 samples. The mean concentration was 40 micrograms L-1. AMCC can be formed in two ways. The first possibility is the dietary intake of isothiocyanates, especially methyl isothiocyanate, which is a component of wine and cruciferous vegetables (such as cabbage, turnips and cress). During the metabolism of isothiocyanates in humans, the sulfur is partly exchanged for oxygen resulting in the formation of the corresponding isocyanate derivatives. The other possibility is the physiological formation of AMCC. In humans, this may occur via a two step process: carbamoylation and methylation, or vice versa. However, as AMCC was identified in about 95% of urine samples, and the standard deviation for the level of AMCC excreted was low, physiological formation seems to be the more probable pathway.     

Persistent organic pollutants in Alaskan ringed seal (Phoca hispida) and walrus (Odobenus rosmarus) blubber

Since 1987, the Alaska Marine Mammal Tissue Archival Project (AMMTAP) has collected tissues from 18 marine mammal species. Specimens are archived in the National Institute of Standards and Technology's National Biomonitoring Specimen Bank (NIST-NBSB). AMMTAP has collected blubber, liver and/or kidney specimens from a number of ringed seals (Phoca hispida) from the areas near Nome and Barrow, Alaska and walruses (Odobenus rosmarus) from several locations in the Bering Sea. Thirty-three ringed seal and 15 walrus blubber samples from the NIST-NBSB were analyzed for persistent organic pollutants (POPs). The compounds determined included PCBs (28 congeners or congener groups), DDT and related compounds, hexachlorobenzene (HCB), hexachlorocyclohexane isomers (HCHs), chlordanes, dieldrin, and mirex. POP concentrations in ringed seal blubber were significantly higher in Barrow than in Nome when statistically accounting for the interaction of age and gender; HCB, however, was not statistically different between the two locations. Unlike males, POP concentrations and age were not significantly correlated in females probably as a result of lactational loss. POP concentrations in walrus blubber were lower than in ringed seal blubber for SigmaPCBs, chlordanes, and HCHs, but higher for dieldrin and mirex. POP concentrations in ringed seals and walrus from Alaska provide further evidence that the western Arctic tends to have lower or similar POP concentrations compared to the eastern Canadian Arctic.     

Effects of Cadmium (CdCl2) on development and hatching of eggs in European squid (Loligo vulgaris Lamarck, 1798) (Cephalopoda: Loliginidae)

This is the first study related to the effects of cadmium (Cd) on the development and hatching of eggs of Loligo vulgaris. The eggs were exposed to concentrations varying from 10 to 100,000 μg Cd/l for up to 1 month. During the study period natural sea water salinity (37 PSU), ambient temperature (ranging 16.5–21.5°C) and light conditions of 12-h light: 12-h dark for 744-h were used prior to the hatching. For 96-h, mortality rate of 100% of the eggs was found at cadmium concentration of 100,000 μg Cd/l, and the same mortality rate of the eggs were found at 1,000 and 10,000 μg Cd/l for 744-h and 696-h, respectively. Hatching took place between hours 456 and 576 in the control group and between hours 480 and 576 in 10 and 100 μg Cd/l groups. Total hatching rates were calculated to be 98.2 ± 1.6% for control group, 99.4 ± 0.6% for 10 μg Cd/l group and 98.6 ± 1.2% for 100 μg Cd/l group. Hatching successes were estimated as 69.5 ± 13.8% for control group, 84.5 ± 8.2% for 10 μg Cd/l group and 76.9 ± 5.9% for 100 μg Cd/l group. In the 100,000 μg Cd/l treatment, the egg degeneration began from animal pole of the eggs in 16 h, and 50% and 100% of them died in the initial stage at 72-h and 96-h, respectively. In the 10,000 μg Cd/l group, the eggs which reached at stage 19 (IX) were deformed and 50% and 100% of them died at 312-h and 696-h, respectively. In 1,000 μg Cd/l group, however, the eggs developed abnormally from stage 21 (X–XI) and reached at stage 29 (XIX), and 50% and 100% of them died in 624-h and in 744-h, respectively. There were significant differences in survival rates of the eggs among the concentrations (p < 0.05). The current study demonstrated that Cd adversely affects the development, survival and hatching of L. vulgaris eggs; however, no mortality was observed in 10 μg Cd/l and 100 μg Cd/l groups.     

Concentrations of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in vacuum cleaner dust collected in Japanese homes

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are shown to be globally distributed, environmentally persistent and bioaccumulative. Although there is evidence that these compounds exist in the serum of non-occupationally exposed humans, the pathways leading to the presence of PFOS and PFOA are not well characterized. The concentrations of PFOS and PFOA in the vacuum cleaner dust collected in Japanese homes were measured. The compounds were detected in all the dust samples and the ranges were 11-2500 ng g(-1) for PFOS and 69-3700 ng g(-1) for PFOA. It was ascertained that PFOS and PFOA were present in the dust in homes, and that the absorption of the dust could be one of the exposure pathways of the PFOS and PFOA to humans. With regard to risk management, it is important to consider the usage of PFOS and PFOA in the indoor environment in order to avoid further pollution.     

Heavy metals in water and in tissues of himri (Carasobarbus luteus) from Orontes (Asi) River, Turkey

Concentrations of heavy metals (Ag, Cd, Cr, Cu, Fe, Ni, Pb ve Zn) were measured in running water and in tissues (muscle, liver, gill, skin and gonads) of one commercially valuable fish species (Carasobarbus luteus) from the Orontes (Asi) River (Güzelburç region) in Hatay (Southeastern Turkey). Results for levels in water compared with national and international water quality guidelines were found at the highest concentrations in international criteria’s WHO, EC and EPA, but Cd, Cu, Ni and Pb were found to exceed permissible level of drinking water in national criteria TSE-266 whereas Fe, Zn and Cr concentrations were within the permissible levels for drinking. The present study showed a significant seasonal variation (p?p?>?0.05), which showed seasonal variation of only Zn (p?C. luteus were below the permissible limit for human consumption, level of Cu being very close to the permissible limit. Consequently, continuous monitoring of heavy metal concentration in edible freshwater fish will be needed in Orontes River.     

The relationship between whole effluent toxicity (WET) and chemical-based effluent quality assessment in Vojvodina (Serbia)

The relationship between whole effluent toxicity (WET) and chemical-based effluent quality assessment across a range of effluent types was examined for the first time in Serbia. WET was determined by Daphnia magna acute tests, while chemical-based toxicity was taken as theoretical for concentrations of priority chemicals and effluent quality assessment based on the valid Serbian regulations. A poor correlation was found between WET and chemical-based effluent quality assessment: positive toxicity tests were found, in general, in cases where samples satisfied the requirements of mandatory effluent monitoring. Statistically insignificant correlation between the predicted and observed toxicity indicated that the presence of priority substances accounted to the overall toxicity only to a certain degree, most probably due to a rather short list of priority pollutants regularly analysed in effluents. Current monitoring requirements neglect hazards that derive from potentially present toxicants and unpredictable toxicity of complex mixtures, which led to poor correlation between the WET and chemical-based results in this study.     

Contamination by polychlorinated biphenyls (PCBs) in striped dolphins (Stenella coeruleoalba) from the Southeastern Mediterranean Sea

Concentrations of polychlorinated biphenyls (PCBs) including dioxin-like PCBs (non-ortho, PCB 77, PCB 126, and PCB 169 and mono-ortho, PCB 105, PCB 118, and PCB 156) were measured in different organs and tissues (melon, blubber, liver, kidney, lung, heart, and muscle tissue) of striped dolphins (Stenella coeruleoalba) from the Eastern Mediterranean Sea (Adriatic Sea). The mean highest levels were in blubber and melon, followed by liver, kidney, lung, heart, and muscle tissue. PCB profiles were similar in all tissues and organs being dominated by the higher chlorinated homologues (hexa-CBs, 55.8-62.1%; penta-CBs, 15.4-20.0%; and hepta-CB PCB 180, 12.7-16.5%). Major PCBs in all tissues were congeners 138 and 153 collectively accounting for 50.6-58.3% of the total PCB concentrations, followed by PCB 101, 105, 118, and 180 constituting from 27.0% to 31.0%. PCB levels were higher in adult males than in adult females. The estimated 2,3,7,8-TCDD toxic equivalents of non- and mono-ortho PCBs were much higher than the threshold level above which adverse effects have been observed in other marine mammals species, suggesting that striped dolphins in this region are at risk for toxic effects.     

Occurrence of diarrhetic shellfish poisoning (DSP) toxins in clams (Ruditapes decussatus) from Tunis north lagoon

The main diarrhetic shellfish toxins, okadaic acid (OA) and dinophysistoxin-1, 2 (DTX-2, 2) were detected by liquid chromatography-tandem mass spectrometry (LC-MS/MS) as pyrenacyl esters in clams (Ruditapes decussatus) collected in Tunis north lagoon from January 2007 to June 2008. Sample analyses by LC-MS/MS displayed OA and related congeners (DTX-2, 2) with a highest detected level of 21 μg OA eq/kg shellfish meat for the samples of January 2007. Nevertheless, all samples were MBA negative. During the study period, potentially toxic dinoflagellate Dinophysis sacculus was recorded all year, blooming at different times. Highest concentrations were recorded during January 2007 with 4.6?×?10(4) cells per liter and 4.10(4) cells per liter in the northern and southern districts, respectively. Results show that there is no significant correlation between D. sacculus densities in water column and diarrhetic shellfish poisoning (DSP) toxins concentrations unregistered in clams. These data reveal that DSP toxicity in clams of Tunis north lagoon is low according to European regulatory limit (160 μg OA eq/kg shellfish meat). However, a potential threat, in this area, is represented by DSP toxic species as D. sacculus and provides grounds for widen and reinforcing sanitary control of the phycotoxin measures in the region.