Method Validation for Quantification of PFOS and PFOA in Human Plasma and a Pilot Study in Blood Donors from Thai Red Cross Society.

Information regarding per- and polyfluorinated substances concentrations in biological samples from the Thai population was still lacking. A sensitive bioanalytical method was developed and validated for the quantification of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) levels in human plasma. Simple protein precipitation and LC-MS/MS techniques were used with stable isotope internal standards of 13C8-PFOS and 13C8-PFOA. The validated method followed the ICH bioanalytical validation guideline, and the results showed good accuracy, precision, and reproducibility. The validated analytical method was then applied to determine PFOS and PFOA concentrations in 50 human plasma samples from the National Blood Center, Thai Red Cross Society. The concentrations were found to be in ranges of <0.91-6.27 ng/mL for PFOS and <0.49-2.72 ng/mL for PFOA. PFOS was also measured separately for its isomers, and the geometric means of the linear isomer (L-PFOS) and branched isomer (br-PFOS) in plasma samples were at 1.85 and 0.41 ng/mL, respectively. Both PFOS and PFOA concentrations were lower in comparison to previous reports from other countries. The present study showed the application of our reliable method to determine PFOS and PFOA in biological samples in order to monitor the human exposure of both chemicals in Thailand.

A cross-sectional study of exposure to mercury in schoolchildren living near the eastern seaboard industrial estate of Thailand.

BACKGROUND: Industrial activity in Thailand's coastal areas has significantly increased mercury concentrations in seawater, causing accumulation through the food chain. Continuous exposure to mercury has been linked to bioaccumulation in living organisms and potential adverse health effects in children. METHODS: Blood samples were collected from 873 schoolchildren aged 6-13 years living in four sites near the eastern seaboard industrial estates of the Gulf of Thailand in 2011. Total mercury level in whole blood (Hg-B) was compared with standard reference values. RESULTS: Mean (± standard deviation) concentrations of Hg-B from schoolgirls (2.19 ± 0.5 µg/L; n = 405) and schoolboys (2.29 ± 0.3 µg/L; n = 468) did not exceed the regulatory limits of the United States Environmental Protection Agency (US EPA), the German Commission on Human Biological Monitoring (HBM I, II) or Clarke's analysis of drugs and poisons reference values. Nevertheless, 67 children (34 girls and 33 boys) had individual values that exceeded the lowest of these standards (4 µg/L). CONCLUSION: The relatively low concentrations of Hg-B detected in this study suggested a relatively low risk for schoolchildren. However, 67 children had elevated mean total Hg-B concentrations, especially in the two sites located nearest the industrial area. This information may serve as an early warning of the potential for pollution to affect children living around industrial areas. Further regular monitoring, including studies assessing the health impact of mercury pollution in this region of Thailand, is to be encouraged.

Serum concentrations of organochlorine pesticides p,p'-DDE in adult Thai residents with background levels of exposure.

In Thailand, DDT was banned for agriculture use in 1983 and for malaria vector control in 1999. However, contamination by DDT and its primary metabolite, p,p'-DDE remains serious environmental and human health concerns. The main focus of this study were i) to investigate serum concentrations of p,p'-DDE and p,p'-DDT as exposure biomarkers for potential adverse health effect in adult Thai residents and ii) to compare the associations of BMI, thyroid hormones, cholesterol, triglycerides and fasting blood sugar levels in human serum with the concentrations of these pesticides. In a total of 1,137 participants were measured blood serum for analyses of p,p'-DDE and p,p'-DDT. The geometric mean concentration (95% confidence interval) for serum total p,p'-DDE concentration was 1,539 (1,242-1,837) ng/g lipid and 1,547 (1,293-1,806) ng/g lipid in adult males and females, respectively. Furthermore, the total amount of serum p,p'-DDE concentration significantly correlated with plasma glucose levels. Neither p,p'-DDE nor p,p'-DDT was significantly associated with serum thyroid hormones levels. Additionally, the high p,p'-DDE/DDT ratio indicates that the exposure is due past rather than recent use of DDT.

Consuming iodine enriched eggs to solve the iodine deficiency endemic for remote areas in Thailand.

BACKGROUND: Evidence showed that the occurrence of iodine deficiency endemic areas has been found in every provinces of Thailand. Thus, a new pilot programme for elimination of iodine deficiency endemic areas at the community level was designed in 2008 by integrating the concept of Sufficient Economic life style with the iodine biofortification of nutrients for community consumption. METHODS: A model of community hen egg farm was selected at an iodine deficiency endemic area in North Eastern part of Thailand. The process for the preparation of high content iodine enriched hen food was demonstrated to the farm owner with technical transfer in order to ensure the sustainability in the long term for the community. The iodine content of the produced iodine enriched hen eggs were determined and the iodine status of volunteers who consumed the iodine enriched hen eggs were monitored by using urine iodine excretion before and after the implement of iodine enrichment in the model farm. RESULTS: The content of iodine in eggs from the model farm were 93.57 µg per egg for the weight of 55 - 60 g egg and 97.76 µg for the weight of 60 - 65 g egg. The biological active iodo-organic compounds in eggs were tested by determination of the base-line urine iodine of the volunteer villagers before and after consuming a hard boiled iodine enriched egg per volunteer at breakfast for five days continuous period in 59 volunteers of Ban Kew village, and 65 volunteers of Ban Nong Nok Kean village. The median base-line urine iodine level of the volunteers in these two villages before consuming eggs were 7.00 and 7.04 µg/dL respectively. After consuming iodine enriched eggs, the median urine iodine were raised to the optimal level at 20.76 µg/dL for Ban Kew and 13.95 µg/dL for Ban Nong Nok Kean. CONCLUSIONS: The strategic programme for iodine enrichment in the food chain with biological iodo-organic compound from animal origins can be an alternative method to fortify iodine in the diet for Iodine Deficiency Endemic Areas at the community level in Thailand.