Mercury in food

There have been numerous reports of possible allergic reactions to mercury and mercury salts and to the mercury, silver and copper in dental amalgam as well as to amalgam corrosion products Studies of the release of mercury by amalgams into distilled water, saline and artificial saliva tend to be conflicting and contradictory but, overall, the data indicate that mercury release drops with time due to film formation and is less than the acceptable daily intake for mercury in food . Further, while metallic mercury can sensitise, sensitisation of patients to mercury by dental amalgam appears to be a rare occurrence. Nevertheless, there is a growing trend to develop polymer-based posterior restorative materials in order to eliminate the use of mercury in dentistry. 

Investigations into the presence of mercury in food have been carried out in a comparatively small number of foods in the UK since 1966. Mercury is included in the analytes measured in the samples of the Total Diet Study. The estimated dietary exposures to total mercury (organic and inorganic) for the general population as determined from the UK TDS (Table 7.5) have remained fairly constant between 0.002 and 0.005 mg/day. The dietary exposures of mean and 97.5th percentile consumers in the UK in 1997 were 0.0031 mg/day and 0.0064mg/day.10 These may be compared with the JECFA PTWI for mercury of 0.005 mg/kg bodyweight/week (of which no more than two-thirds should be methyl mercury),31 which is equivalent to 0.043 mg/day for a 60 kg adult. The dietary exposures are similar to those in the USA (0.008 mg/day)8 and the Netherlands (0.002 mg/day)7 but lower than New Zealand (0.013 mg/day).18... 

Great Britain Ministry of Agriculture, Fisheries and Food, Survey of Mercury in Food A Supplementary Report, Her Majesty s Stationery Office, London, 1973. 

Dabeka, R.W., Bradley, P., McKenzie, A.D. Routine, high-sensitivity, cold vapor atomic absorption spectrometric determination of total mercury in foods after low-temperature digestion. J. AOAC Int. 85, 1136-1143 (2002)... 

T5. Thorpe, V. A., Determination of mercury in food products and biological fluids by aeration and flameless atomic absorption spectrophotometry. J. Ass. Offic. Anal. Chem. 54, 206-210 (1971). 

During long-term constant exposure (several months) to methyl mercury in food, there is a linear relationship between daily intake of methyl mercury and the concentration of mercury in blood. The mercury concentration in blood (pg/L) corresponds to the daily intake of methyl mercury (pg/ day) multiplied by 0.5-1. When exposure is continuous, the blood mercury concentration is proportional to the concentration in the brain, the critical organ for methyl mercury toxicity. Because of mercury s short half-life in the blood (2-4 days), evaluation of blood mercury is of limited clinical value if a substantial amount of time has passed since time of exposure [43]. 

E. Hahn, K. Hahn, M. Stoeppler, Bird feathers as bioindicators in areas of the German Environmental Specimen Bank - bioaccumulation of mercury in food chains and exogenous deposition of atmospheric pollution with lead and cadmium, Sci. Total Environ., 139/140 (1993), 259-270. 

Total mercury in food in Croatia is limited from 0.01 in beverages to 1.5 mg kg in canned flsh, which is substantially higher than in other countries where the highest value for fish is 0.5 mg kg [39]. 

Until 1997, in Germany the Federal Health Agency (EGA 1997) published annual guideline values for lead, cadmium, and mercury in different types of food. For a long time these values provided the basis for the control and monitoring of the current levels of cadmium, lead, and mercury in food. Today, these values have been substituted by setting maximum levels in the previously mentioned EG-Regulation. 

Environmental contamination with mercury leads to a critical concentration effect in animals that occupy higher positions in the food chain. Concentrations of 10 ppm Hg and more have been found in certain fish. Although the tolerated concentration of mercury in foods, e g. 

Hoover, W.L., Melton, J.R. and Howard, P.A. (1971) Determination of trace amounts of mercury in foods by flameless atomic absorption. J. Ass. Off. Anal. Chem., 54, 860-865. 

Marts, R.W. and Blaha, J.J. (1983) Mixed acid solubilization procedure for determination of total mercury in food samples. J. Assoc. Off. Anal. Chem., 66,1421-1423. 

Clearly, effects which have to be studied are the extent to which the enhanced levels in the contaminated soils now characteristic of urban areas, lead to increased trace-element levels in plants grown for human or animal consumption, the extent to which increased trace-element uptake can lead to phytotoxic effects and the possibility of toxic effects on livestock and human beings. The possible consequences of the permanent presence of enhanced levels of elements such as cadmium and mercury in food chains are so far-reaching and unpredictable that there is everything to be said for preventing the development of such a situation. 

While mercury is now a general urban contaminant, and urban soils can be expected to contain about five or six times as much total mercury as uncontaminated rural soils, little is known about the effect this level of contamination has on plant uptake. According to Goldwater [323], the concentration of mercury in foods does not appear to have changed substantially over the past 30 years, and... 

Petring L, Alonso MI, Audrey D et al (2001) An evaluation of analytical techniques for determination of lead, cadmium, chromium, and mercury in food-packaging materials. Fresenius J Anal Chcm 370(1) 76-81... 

AND Other Heavy Metals (1971). First Report Survey oj Mercury in Food. HMSO, London. 

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