No abstract

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.

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.

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.

Mitotane is an important adrenalytic drug for the treatment of adrenal cancer whose use is limited by toxicity. Reports from another laboratory indicated that a methylated homolog of Mitotane (Mitometh) tested in guinea pigs possessed comparable adrenalytic activity but was less toxic than Mitotane. This observation prompted us to undertake a comparative study of these two drugs on the basis that Mitometh may be a superior agent for the treatment of adrenal cancer. Preliminary studies in guinea pigs failed to show a significant adrenalytic effect for either Mitotane or Mitometh. Thus, we extended the study to 13 mongrel dogs weighing 12-15 kg that were treated daily with Mitometh or Mitotane (50-100 mg/kg) for 6 or 12 days. Cortisol decreased to undetectable levels and adrenocorticotropic hormone (ACTH) rose to 10 times the baseline levels within 72 h in Mitotane-treated animals. Despite the achievement of similar drug levels, Mitometh treatment in dogs failed to suppress cortisol or increase ACTH. To determine whether these differences were due to differences in bioavailability, we measured the relative concentration of Mitotane and Mitometh in homogenates of adrenal cortex obtained from Mitotane- and Mitometh-treated dogs. The adrenal concentration of Mitometh determined in Mitometh-treated dogs was 5 times higher than the concentration of Mitotane measured in Mitotane-treated animals. Whereas the adrenal glands of Mitotane-treated dogs showed hemorrhage and necrosis, the Mitometh-treated animals showed no adrenal damage. Despite the lack of adrenalytic activity, Mitometh maintained its toxicity as demonstrated by microscopic evidence of hepatic necrosis and an increase in hepatic enzymes. The adrenalytic effects of both agents was also studied in vitro using a human functioning adrenal cortical carcinoma cell line, NCI-H295. Whereas Mitotane strongly suppressed cell growth, Mitometh had a weaker effect. We conclude that Mitometh is not likely to be effective in the therapy of adrenal cancer. Moreover, the results of this study are supportive of the view that metabolic transformation of Mitotane is in some way linked to its adrenalytic action.