Carcinogenic and non-carcinogenic risk assessment of heavy metals contamination in duck eggs and meat as a warning scenario in Thailand.

The aim of this study was to determine the levels of Pb, Cd, Co and Cr in duck eggs and duck meat and to assess the risk of carcinogenic and non-carcinogenic effects caused by the consumption of duck products collected in Thailand. The human health risk assessment refers to the formulation of the USEPA standard focused on Estimated Daily Intake (EDI), Incremental Lifetime Cancer Risk (ILCR), Target Hazard Quotient (THQ) and Total Target Hazard Quotient (TTHQ). Ninety-eight percent of duck egg samples in this study were contaminated with Pb, with the average level typically above the standard limit. The EDI evaluation of heavy metal in children was the highest for all metals in the eggs. The calculated ILCR levels of Pb, Cd and Cr in eggs and meat consumption were higher than 10-4 in children, adults, males, and females. Children were at risk when consuming contaminated duck eggs and the risk was higher than in adults by 3.9 times for Pb, Cd and Cr. This finding suggests that there is a high probability of cancer risk, particularly for children, which is higher than adults by absorption of these carcinogenic heavy metals through eggs. The calculation of THQ if consuming heavy metals contaminated duck eggs and meat in human exposure (70years) could conclude that the THQ male was higher than the female for all metals. However, the calculations of TTHQ for Pb, Cd, Co and Cr contamination in a duck egg and meat scenario for adults, males and females were still below the standard limit of 1, which means there was no risk, although there could be adverse health effects. This study suggested that children should be the focus of long-term monitoring for evaluating the carcinogenicity of these metals, more specifically in males.

Comparison of zinc, lead, cadmium, cobalt, manganese, iron, chromium and copper in duck eggs from three duck farm systems in Central and Western, Thailand.

This was a comparative study of the heavy metal levels (Zn, Pb, Cd, Co, Mn, Fe, Cr and Cu) in eggs from free grazing duck, small-scale, and large-scale farms in central and western regions of Thailand. A questionnaire was used to gather demographic data for the analysis of heavy metal contamination in feed, drinking water and wastewater. The correlation between the amounts of heavy metal contamination in eggs was studied against the heavy metals found in feed, drinking water and wastewater. The levels of Pb, Cd, Cr and Cu in eggs from large-scale farms were significantly higher than small farms and free grazing farms at P < 0.001. Zn in eggs from free grazing farms was higher than in the small farms and large-scale farms sampled. The contamination of Pb in eggs from all types of farms exceeded the standard limits of ACFS 6703-2005. The average levels of Pb in the eggs from small-scale farms correlated significantly with the level of Pb found in the feed at P < 0.05, while the average levels of Pb in eggs from free grazing duck farms correlated significantly with the levels of Pb found in the drinking water at P < 0.05. Additionally, the average level of Cu in duck egg from large-scale farms correlated significantly with the level of Cu found in the feeds at P < 0.001. Furthermore, from a calculation of the provisional tolerable daily intake (WHO-FAO) of heavy metals in this study, it was concluded that consumers face health risks from Cd contamination. Thus, heavy metal contamination, especially Pb and Cd in duck egg, must be of concern due to the health risks and the route of crucial heavy metals contamination should be elucidated and long - term monitoring of heavy metals posing health effects in farm systems should be carried out.

Heavy Metal (Cd and Pb) and Aflatoxin Contamination in Tissues and Eggs from Free Grazing Ducks and Their Environment in Central Thailand.

The cross-sectional study of heavy metals and aflatoxins was conducted by studying duck egg, blood, liver, feed, and water samples from 11 free grazing farms. The duck feed, soil, and rice samples were lower than the standard limit for aflatoxins at 20 ng g-1. The highest levels of aflatoxin were detected in the liver, intestine, and egg yolk; these were 3.04, 1.73, and 4.56 ng g-1 respectively, while the average levels were 1.6 ± 0.73, 1.31 ± 0.23, and 1.87 ± 0.99 ng g-1, respectively. Interestingly, aflatoxin was not detected in any of the egg white albumin samples (90/90 samples), whereas aflatoxin contamination was predominantly found in the yolk. Additionally, the means and standard deviations of Pb and Cd found in the duck eggs were 118.61 ± 22.25 and 13.84 ± 9.06 ng g-1 respectively. The maximum levels of Pb and Cd in eggs were 134.34 and 29.72 ng g-1, respectively. Moreover, Pb contamination occurred in the duck liver tissue in 93.61% (88/94) of the samples, whereas Cd contamination was found in 100% (100/100). The maximum levels of Pb and Cd in the duck liver tissues were 606.16 and 22,946.20 ng g-1, which was higher than those in the eggs. Pb contamination in the water from rice paddy fields after grazing was significantly higher than that in water samples taken before grazing. This is the first report of Pb and Cd contamination in blood, egg, and liver samples of free grazing ducks in Thailand.

Health Risk Contamination of Heavy Metals in Yolk and Albumen of Duck Eggs Collected in Central and Western Thailand.

Two hundred duck egg samples were collected from 20 farms in Central and Western Thailand. The levels of Zn, Co, Mn, Fe, and Cr in yolks were found significantly higher than in albumen, whereas the levels of Cd and Cu contaminations in egg albumen were significantly higher than in yolks. The mean level of Pb contamination in whole eggs was 4.06 ± 2.70 mg kg-1 dry weight. This level was higher than the Thai agricultural standard no. 6703-2005 for duck eggs set at 0.1 ppm for the magnitude of 40.6 times. In addition, 98% (196/200) of duck egg samples had Pb levels higher than the standard limit. However, the calculation of daily intakes of Pb, Cd, and Cu contamination in the current study of duck eggs shows that these metals were lower than the World Health Organization and the Food and Agriculture Organization provisional tolerated daily intake. These levels may, however, present a health risk resulting from a long-term exposure. It can be concluded that consumers may be at risk of Pb, Cd, and Cu contamination if they consume contaminated duck eggs. In addition, long-term monitoring of the health risks of heavy metals contamination should be conducted concerning the duck egg production system in Thailand.

The toxic effects and fate of intravenously administered zearalenone in goats.

To clarify the toxic effects and fate of zearalenone (ZEA) in ruminants, we studied histopathological changes and toxicokinetic profiles in goats administered with a single intravenous (iv) injection of ZEA at doses of 2.4 mg/kg bw and 1.2 mg/kg bw, respectively. The expression of the mRNA of estrogen receptor (ER) alpha and beta in tissues was also investigated. The histopathological study revealed that ZEA caused hepatocellular swelling and lymphocytic infiltration in the liver, kidney, and uterus. The expression of ERalpha mRNA was enhanced by ZEA in association with the histopathological changes, indicating the possible involvement of ERalpha in the toxic effects of ZEA. For toxicokinetic profiles, blood plasma, urine, and feces were collected consecutively after iv injection of ZEA and analyzed for ZEA and its metabolites with high performance liquid chromatography (HPLC). alpha-Zearalenol (ZOL) and beta-ZOL were detected with ZEA, but alpha-zearalanol (ZAL), beta-ZAL, and zearalanone were below the detection limits. The distribution half-life (t(1/2alpha)) and elimination half-life (t(1/2beta)) of ZEA were 3.15 and 28.58h, respectively. ZEA, alpha-ZOL, and beta-ZOL were excreted in urine and feces, with beta-ZOL being the predominant metabolite. The ZEA and ZOL in urine were largely in their glucuronide and/or sulphate conjugated forms, while those in feces were largely in their free forms. This study showed the toxic effect of zearalenone and its metabolites, and their pharmacokinetic characteristics in goats.

The effect of feeding piglets with the diet containing green tea extracts or coumarin on in vitro metabolism of aflatoxin B1 by their tissues.

To clarify whether enzymes involved in aflatoxin B1 (AFB1) metabolism in pigs respond to antioxidant agents, the effect of feeding piglets with diets containing green tea extracts (Sunphenon) and coumarin on in vitro AFB1 metabolism by their liver and intestinal tissues was studied. The results showed that coumarin reduced AFB1-DNA adduct formation by both liver and intestinal microsomes, while Sunphenon did not have any effects. Both coumarin and Sunphenon enhanced the glutathione S-transferase (GST) activity to conjugate AFB1 to glutathione GSH in the intestine, although no effects were noted in the liver. Changes of the expression of mRNA of GSTA2 and GSTO1 were not in parallel with the observed changes of GST activity, suggesting that other GST subtypes are involved in the GST activity toward AFB1. As for lipophilic-free AFB1 metabolites, coumarin reduced the liver microsomal conversion of AFB1 to aflatoxin M1 (AFM1) and aflatoxin Q1 (AFQ1), but Sunphenon exerted no effects. Both coumarin and Sunphenon enhanced the conversion of AFB1 to aflatoxicol in the liver. All the results suggest that feeding with a diet containing coumarin affects AFB1 metabolism to enhance AFB1 detoxification through the suppression of P450 enzyme activity in the liver and the enhancement of GST activity in the intestine. Feeding with a diet containing Sunphenon enhances AFB1 detoxification, but the effects are noted mainly in the intestine.

Comparative activities of glutathione-S-transferase and dialdehyde reductase toward aflatoxin B1 in livers of experimental and farm animals.

In order to gain a better understanding of the relative activities of glutathione-S-transferase (GST) and aldehyde reductase toward aflatoxin B1 (AFB1) in relation to the variation of species susceptibilities, we studied the in vitro cytosolic GST and reductase activities in liver tissues from male Fischer rats, ICR mice and golden hamsters, adult male rainbow trouts and female piglets. The GST activity was determined by incubating the liver cytosol with glutathione (GSH) and AFB1 in the presence of the hamster liver microsomes to metabolize AFB1 to AFB1-8, 9-epoxide. The reaction product, AFB1 and GSH conjugate (AFB1-GSH), was quantified with HPLC. The reductase activity was determined by incubating liver cytosol with AFB1-dialdehyde, followed by the quantification of the metabolic product, AFB1-dialcohol, with HPLC. All the animal species possessed the GST activities, and AFB1-GSH formed increasingly with the increase of the AFB1 concentration according to the model of first-order enzyme reaction kinetics. The V(max) and K(m) values of the GST activities in rodent species were higher and lower, respectively, than those in the trout and pig, being consistent with the relative susceptibilities to AFB1 of these animal species. However, no relationship was noted between the reductase activity and species susceptibility. Thus, the result of this study shows that GST toward AFB1, but not aldehyde reductase, is a determinant of the variation of species susceptibilities.