Short-term exposure of Nile Tilapia (Oreochromis niloticus) to mercury: histopathological changes, mercury bioaccumulation, and protective role of metallothioneins in different exposure routes.

To investigate effects of short-term mercury (Hg) exposure in tilapia (Oreochromis niloticus) including histopathological changes, Hg bioaccumulation, and protective role of metallothionein (MT) in different exposure routes, adult tilapias were intraperitoneally injected, orally intubated, or semistatically exposed to 0.5, 1, 2, 5 µg/g mercuric chloride. Histopathology, autometallography (AMG), inductive coupled plasma-atomic emission spectrometry (ICP-AES), and MT immunohistochemistry were determined at 0, 3, 6, 9, 12, and 15 days postexposure. Microscopic lesions were observed in the kidney, hepatopancreas, spleen, and intestine. AMG positive grains were found in renal tubule epithelium, melanomacrophage centers (MMCs), and intestinal epithelium of treated tilapias. Hg concentrations measured by ICP-AES in abdominal visceral organs were significantly higher than in other organs. All exposure routes caused lesions of increasing severity and Hg accumulations in a dose-dependent manner. Semistatic groups produced the highest intensity of lesions, AMG positive staining, as well as total Hg concentrations. Positive MT expression in renal tubule epithelium, pancreatic acini, and splenic MMCs was observed only in semistatic groups. The semistatic exposure route demonstrated the most significant microscopic lesions, Hg bioaccumulation, and MT expression.

Total and inorganic arsenic in natural and aquacultural freshwater fish in Thailand: a comparative study.

Total and inorganic arsenic were determined in 108 samples of four freshwater fish species collected from natural water sources and aquaculture systems in the central region of Thailand between March and May 2010. Concentrations of total and inorganic arsenic (dry wt) and percentages of inorganic arsenic in four aquacultural fish species were not significantly different from those found in natural fish. Inorganic arsenic levels found in the four fish species from both sources in this study were much lower than the Thai regulatory standard of 2 µg/g, and hence are considered safe for human consumption.

Dietary intake of total and inorganic arsenic by adults in arsenic-contaminated Dan Chang district, Thailand, using duplicate food approach.

Dan Chang district, approximately 100 km west of Bangkok, was a site of tin mines operated almost 40 years ago. Mining operations caused arsenic contamination in soil, surface water, and groundwater within the district. The specific aim of this study was to estimate the dietary intakes of total and inorganic arsenic in 60 adults (30 males and 30 females) residing in Dan Chang district, using a duplicate food approach. The daily intake rates of inorganic arsenic ranged from 0.496 to 1.817 µg/kg BW for males and 0.342 to 1.778 µg/kg BW for females.

Dietary intake of total and inorganic arsenic by adults in arsenic-contaminated area of Ron Phibun district, Thailand.

Ron Phibun District, approximately 800 km south of Bangkok, is the site of tin mines operated almost 100 years ago. As a result of mining activities, arsenic contaminated the soil and groundwater of the district. The specific aim of this study was to estimate the dietary intakes of total and inorganic arsenic in 20 adults (10 males and 10 females) residing in Ron Phibun District by a duplicate food approach for 7-consecutive days. The weekly intake rates of inorganic arsenic ranged from 5.54 to 13.3 microg/kg BW for males and 6.11-12.1 microg/kg BW for females.

Aflatoxin M(1) contamination in raw milk within the central region of Thailand.

Aflatoxin M(1) (AFM(1)) was found in all of the 240 raw milk samples collected from milk tanks of 80 dairy farms at a collecting center in the central region of Thailand. Milk samples from individual farms were collected in three seasons. The average concentration of AFM(1) in milk samples collected in winter (0.089 +/- 0.034 microg/L) was significantly higher than those in rainy season (0.071 +/- 0.028 microg/L) and summer (0.050 +/- 0.021 microg/L). The present study suggests that regulatory limits for AFM(1) are needed to regulate and ensure the quality of raw milk and milk products in Thailand.

Occurrence of aflatoxin M1 in pasteurized milk of the School Milk Project in Thailand.

Concentrations of aflatoxin M1 (AFM1) were determined in 150 pasteurized milk samples from the School Milk Project in Thailand. Milk samples were collected from 50 schools in the Central region of Thailand in three seasons: summer (May to June 2006), the rainy season (August to September 2006), and winter (December 2006 to January 2007). AFM1 was isolated by using an immunoaffinity column and quantified by high-performance liquid chromatography. All of the 150 pasteurized milk samples were contaminated with AFM1, and the concentrations were within the U.S. regulatory limit of 0.5 microg/liter. The highest concentration of AFM1 found in school milk samples was 0.114 microg/liter. The mean concentration of AFM1 in milk samples collected in winter was significantly higher than the mean concentrations found in the rainy season and summer. Further monitoring of school milk to evaluate the status of contamination of AFM1 is necessary, with a special emphasis on samples collected in the rainy season and winter. Thailand is one of several countries that have no regulatory limits for AFM1 in milk and milk products. The results of this study suggest that safety limits for AFM1 are needed for regulating and ensuring the quality of milk and milk products in Thailand.

Health risk assessment of inorganic arsenic intake of Ronphibun residents via duplicate diet study.

OBJECTIVE: To assess health risk from exposure to inorganic arsenic via duplicate portion sampling method in Ronphibun residents. MATERIAL AND METHOD: A hundred and forty samples (140 subject-days) were collected from participants in Ronphibun sub-district. Inorganic arsenic in duplicate diet sample was determined by acid digestion and hydride generation-atomic absorption spectrometry. Deterministic risk assessment is referenced throughout the present paper using United States Environmental Protection Agency (U.S. EPA) guidelines. RESULTS: The average daily dose and lifetime average daily dose of inorganic arsenic via duplicate diet were 0.0021 mg/kg/d and 0.00084 mg/kg/d, respectively. The risk estimates in terms of hazard quotient was 6.98 and cancer risk was 1.26 x 10(-3). CONCLUSION: The results of deterministic risk characterization both hazard quotient and cancer risk from exposure inorganic arsenic in duplicate diets were greater than safety risk levels of hazard quotient (1) and cancer risk (1 x 10(-4)).

Probabilistic Risk Assessment of Inorganic Arsenic via Consumption of Herbs Collected in Thailand.

Total and inorganic arsenic contents in ten commonly consumed Thai herbs, namely, bird's eye chili, cayenne pepper, celery, garlic, holy basil, kitchen mint, lemongrass, pepper, shallot, and sweet basil, were determined using atomic absorption spectrometry coupled with a hydride generation system (HG-AAS). Total arsenic contents in fresh herbs and lyophilized herbs ranged from 3.39 to 119 ng/g wet weight (wet wt) and from 41.0 to 156 ng/g dry weight (dry wt), respectively. Inorganic arsenic contents in fresh herbs and lyophilized herbs ranged from 2.09 to 26.9 ng/g (wet wt) and from 23.5 to 55.5 ng/g (dry wt), respectively. Percentages of inorganic arsenic to total arsenic in herbs ranged from 22.7 to 62.0%. High percentages of inorganic arsenic to total arsenic were found in celery, lemongrass and sweet basil. Total arsenic contents in the studied herbs were lower than the maximum limits of Thai and Chinese regulatory standards, set at 2,000 ng/g in foods (excluding aquatic animals and seafood) and 500 ng/g in fresh vegetables, respectively. Total and inorganic arsenic contents in the studied herbs were comparable to or lower than the levels found in other studies in the EU and China. Lifetime average daily dose (LADD) and cancer risk (CR) of inorganic arsenic exposure to commonly consumed herbs were evaluated using probabilistic risk assessment (PRA) by @RISK software version 6.0 of Palisade cooperation. All calculated LADD and CR values from all herbs did not exceed the acceptable levels. It can be concluded that there were very low cancer risks of inorganic arsenic exposure from the consumption of the studied herbs.

Total and inorganic arsenic contents in some edible zingiberaceous rhizomes in Thailand.

The arsenic accumulation in rhizomes of Zingiberaceous plants was determined by atomic absorption spectrometry interfaced with hydride generation system (HG-AAS). The raw herbal materials, rhizomes, were collected from different regions of Thailand between December 2011 and January 2012. Six well-known Zingiberaceous plants, 16 samples from each and a total of 96 samples, were analyzed Alpinia galanga (Khaa), Boesenbergia rotunda (Kra-chaai), Curcuma longa (Khamin-chan), Curcuma zedoaria (Khamin-oi), Zingiber cassumunar (Plai) and Zingiber officinale (Ginger). Concentrations of total arsenic based on dry weight were 92.4 ± 9.2, 103.5 ± 20.8, 61.7 ± 12.5, 89.8 ± 17.5, 106.7 ± 19.5 and 69.3 ± 11.8 ng/g, respectively and inorganic arsenic were 48.8 ± 7.0, 66.3 ± 12.7, 25.5 ± 5.0, 38.7 ± 4.7, 71.2 ± 11.6, and 38.5 ± 5.5 ng/g, respectively. Among these, Plai and Kra-chaai exhibited the highest levels of total arsenic and inorganic arsenic accumulation that remind consumers to be aware of excess consuming of these rhizomes. On the contrary, the lowest value found in Khamin-chan indicating natural dietary supplements and herbal medicines comprising Kamin-chan are safe from arsenic poison. All investigated amounts of total and inorganic arsenic were much lower than limits recommended by Thai Food and Drug Administration.

Total and inorganic arsenic in rice and rice bran purchased in Thailand.

Concentrations of total and inorganic arsenic were determined in 180 samples of polished and brown rice of three rice types, namely white, jasmine, and sticky, and 44 samples of rice bran from these three rice types purchased in Thailand. Concentrations (expressed in nanograms per gram) of inorganic arsenic in polished white, jasmine, and sticky rice were 68.3 ± 17.6 (with a range of 45.0 to 106), 68.4 ± 15.6 (41.7 to 101), and 75.9 ± 24.8 (43.5 to 156), respectively, while those in the three brown rice samples were 124 ± 34.4 (74.5 to 193), 120 ± 31.6 (73.1 to 174), and 131 ± 35.6 (78.0 to 188), respectively. Inorganic arsenic concentrations (expressed in nanograms per gram) in rice bran produced from the three rice types were 633 ± 182 (375 to 919), 599 ± 112 (447 to 824), and 673 ± 195 (436 to 1,071), respectively. Rice bran contained concentrations of total and inorganic arsenic approximately seven and nine times higher, respectively, than those found in the corresponding polished rice. The levels of inorganic arsenic in the three rice types of both polished and brown rice were within the only published regulatory limit of 200 ng/g.

Total and inorganic arsenic in freshwater fish and prawn in Thailand.

Total and inorganic arsenic levels were determined in 120 samples of eight freshwater animal species collected from five distribution centers in the central region of Thailand between January and March 2011. Eight species with the highest annual catch, consisting of seven fish species and one prawn species, were analyzed. Concentrations of inorganic arsenic (on a wet weight basis) ranged from 0.010 µg/g in giant prawn (Macrobrachium rosenbergii) to 0.230 µg/g in striped snakehead (Channa striata). Climbing perch (Anabas testudineus) exhibited the highest mean concentrations of total arsenic (0.459 ± 0.137 µg/g), inorganic arsenic (0.121 ± 0.044 µg/g), and percentage of inorganic arsenic (26.2%). Inorganic arsenic levels found in freshwater animals in this study were much lower than the Thai regulatory standard of 2 µg/g.

Concentrations of total and inorganic arsenic in fresh fish, mollusks, and crustaceans from the Gulf of Thailand.

Concentrations of total and inorganic arsenic were determined in 120 samples of eight marine animals collected from the Gulf of Thailand between March and May 2008. Two species with the highest annual catch from each of four marine animal groups were analyzed: fish (Indo-Pacific mackerel and goldstripe sardine), bivalves (green mussel and blood cockle), cephalopods (pharaoh cuttlefish and Indian squid), and crustaceans (banana prawn and swimming crab). Concentrations of inorganic arsenic based on wet weight ranged from 0.012 µg/g in Indian squids to 0.603 µg/g in blood cockles. Average percentages of inorganic arsenic with respect to total arsenic ranged from 1.2% in banana prawns to 7.3% in blood cockles. Blood cockles also exhibited the highest levels of total arsenic (5.26 ± 2.01 µg/g) and inorganic arsenic (0.352 ± 0.148 µg/g). The levels of inorganic arsenic in the study samples were much lower than the Thai regulatory limit of 2 µg/g (wet wt) and hence are safe for human consumption.