Dietary exposures to eight metallic contaminants of the Hong Kong adult population from a total diet study.

Dietary exposures to eight metallic contaminants, aluminium (Al), antimony (Sb), cadmium (Cd), lead (Pb), methylmercury (MeHg), nickel (Ni), tin (Sn) and vanadium (V), of the Hong Kong adult population were estimated using the total diet study (TDS) approach. The estimated mean exposures of Al (0.60 mg kg(-1) bw week(-1)), Sb (0.016-0.039 µg kg(-1) bw day(-1)), Cd (8.3 µg kg(-1) bw month(-1)), Pb (0.21 µg kg(-1) bw day(-1)), MeHg (0.74 µg kg(-1) bw week(-1)), Ni (3.1 µg kg(-1) bw day(-1)), Sn (0.029-0.031 mg kg(-1) bw week(-1)) and V (0.13 µg kg(-1) bw day(-1)) were well below the relevant health-based guidance values (HBGVs) where available. However, dietary exposures to MeHg of women aged 20-49 years (child-bearing age) accounted for 150% of the provisional tolerable weekly intake (PTWI) and to Al and Cd of some high consumers were found exceeding or approaching the HBGVs. The major food contributors of MeHg were fish and seafood (90%), of Al were non-alcoholic beverages including tea (33%), and of Cd were vegetables (36%). MeHg exposure during pregnancy was a public health concern in Hong Kong due to potential health risks to the foetus. Results suggest that there is a need to continue monitoring the exposures to metallic contaminants, especially Al, Cd and MeHg, of the Hong Kong population.

Quantitative risk-benefit analysis of fish consumption for women of child-bearing age in Hong Kong.

Maternal fish consumption is associated with both risks from methylmercury (MeHg) and beneficial effects from omega-3 fatty acids to the developing foetal brain. This paper assessed the dietary exposure to MeHg of women of child-bearing age (20-49 years) in Hong Kong, and conducted risk-benefit analysis in terms of the effects in children's intelligent quotient (IQ) based on local data and the quantitative method derived by the expert consultation of FAO/WHO. Results showed that average and high consumers consume 450 and 1500 g of fish (including seafood) per week, respectively. About 11% of women of child-bearing age had a dietary exposure to MeHg exceeding the PTWI of 1.6 µg kg(-1) bw. In pregnant women MeHg intake may pose health risks to the developing foetuses. For average consumers, eating any of the 19 types of the most commonly consumed fish and seafood during pregnancy would result in 0.79-5.7 IQ points gain by their children. For high consumers, if they only ate tuna during pregnancy, it would cause 2.3 IQ points reduction in their children. The results indicated that for pregnant women the benefit outweighed the risk associated with eating fish if they consume different varieties of fish in moderation.

Dietary exposure of Hong Kong adults to fatty acid esters of 3-monochloropropane-1,2-diol.

A total of 290 individual food samples were collected in Hong Kong, China, for 3-monochloropropane-1,2-diol (3-MCPD) fatty acid esters analysis. Most samples were processed food and in ready-to-eat form. The results show that the levels of 3-MCPD fatty acid esters were high in biscuits, fats and oils, snacks and Chinese pastry with mean bound 3-MCPD levels of 440, 390, 270 and 270 µg kg⁻¹, respectively. The dietary exposures to bound 3-MCPD of average and high adult consumers were estimated to be 0.20 and 0.53 µg kg bw⁻¹ day⁻¹, respectively. The primary toxicological concern of 3-MCPD fatty acid esters is its potential to release 3-MCPD in vivo during digestion in the gastrointestinal tract. 3-MCPD would affect the kidney, the central nervous system and the male reproductive system of rats. Assuming that 100% of the 3-MCPD was released from 3-MCPD fatty acid esters by hydrolysis in the digestive system, the dietary exposures to 3-MCPD for average and high adult consumers were only 10% and 26% of the provisional maximum tolerable daily intake (PMTDI) of 3-MCPD established by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA) (2 µg kg bw⁻¹ day⁻¹), respectively. The results suggest that both average and high adult consumers are unlikely to experience major toxicological effects of 3-MCPD.

Trimethylamine oxide, dimethylamine, trimethylamine and formaldehyde levels in main traded fish species in Hong Kong.

Levels of trimethylamine oxide (TMAO), dimethylamine (DMA), trimethylamine (TMA) and formaldehyde (FA) were studied in 266 different fishes, including fresh/frozen raw whole fishes of 89 different species that traded in Hong Kong, China. Determination of TMAO can confirm the source of DMA and FA if present in the sample. These samples were purchased from different commercial outlets between April and August 2007. All samples of raw whole fish were identified for their species by the Agriculture, Fisheries and Conservation Department. The content of TMAO was determined by high-performance liquid chromatography (HPLC) coupled with a chemiluminescent nitrogen detector. The possible decomposition products of TMAO, DMA and TMA were analysed by headspace solid-phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC-MS), while FA was conducted by steam distillation then quantified by a HPLC. The range for TMAO of all samples was <5-3800 mg kg(-1) with median of 970 mg kg(-1), while the endogenous enzymatic cleavage products DMA, TMA and FA were in the range of <2-320, <1-190 and <1-160 mg kg(-1), respectively. These cleavage products were mainly found in three fish species, Harpadon nehereus, Saurida elongata and Saurida tumbil, that belong to the family Synodontidae (Lizardfishes) and subfamily Harpadontinae. Besides, freshwater fish species, namely, Micropterus salmoides, Oreochromis niloticus niloticus and Siniperca chuatsi, were found to contain TMAO in the range of 510-760, 85-720 and 400-640 mg kg(-1), respectively.