COMMITTEE ON TOXICITY OF CHEMICALS IN FOOD, CONSUMER
PRODUCTS AND THE ENVIRONMENT
COT Statement on the 2006 UK Total Diet Study of Metals and Other
Elements
http://cot.food.gov.uk/pdfs/cotstatementtds200808.pdfIssue
1. The Food Standards Agency (FSA) has completed a survey of aluminium,
antimony, arsenic, barium, bismuth, cadmium, chromium, copper, germanium,
indium, lead, manganese, mercury, molybdenum, nickel, palladium, platinum,
rhodium, ruthenium, selenium, strontium, thallium, tin and zinc in the 2006 Total Diet
Study (TDS). The results provide up to date information on the concentrations of
these elements in foods and were used to estimate dietary exposures for UK
consumers. The Committee was asked to comment on the survey results and assess
if the levels of any of the elements in the diet posed a risk to human health. The COT
last evaluated population and consumer exposures to twelve of these elements
(aluminium, arsenic, cadmium, chromium, copper, lead, manganese, mercury, nickel,
selenium, tin and zinc) in 2003, using data from the 2000 TDS1. Eleven other
elements (antimony, barium, bismuth, germanium, molybdenum, palladium, platinum,
rhodium, ruthenium, strontium and thallium) were last analysed in the 1994 TDS and
evaluated by the COT in 19982; and indium was included for the first time in the 2006
TDS.
5. At present there are no specific limits on the levels of trace elements, minerals
or other micronutrients that may be contained in supplements sold under food law,
although the EU is currently in the process of setting maximum permitted levels for
vitamins and minerals in dietary supplements. Industry guidance on upper levels of
vitamins and minerals is available for manufacturers of supplements to ensure levels
are not excessive. However, the supplements industry is not obliged to follow this
guidance and is only bound by the provisions of the Food Safety Act, which make it
an offence to offer for sale a food product that is injurious to health
8. Most of the food groups had aluminium concentrations lower than or similar to
those reported in the 2000 TDS, the exceptions being bread, meat products, and
other vegetables groups. The miscellaneous cereals group had the highest mean
concentration of aluminium (17.5 mg/kg), although this was lower than the
concentration in the 2000 TDS (19 mg/kg). The miscellaneous cereals group was the
main contributor to the population dietary exposure (42%) to aluminium. Possible
sources of aluminium in this food group include aluminium compounds present
naturally, aluminium-containing additives, and contamination from processing and
storage of food in aluminium-containing utensils.
9. Barium concentrations were similar to or lower than those reported in the 1994
TDS except for the nuts group, in which the mean concentration was 131 mg/kg
compared to 56 mg/kg in 1994.
school children, young people, institutionalised elderly and vegetarian groups; and
mean-level intake for pre-school children)
exceeded the PTWI set by the JECFA and
the EFSA (equivalent to 143 μg/kg body weight/day) by up to 2.4-fold. The current
average population exposure to aluminium (5.4 mg/day) was increased compared to
that reported in the 2000 and 1997 total diet studies (4.7 mg/day and 3.4 mg/day,
respectively) but lower than previous estimates (10 mg/day and 11 mg/day in 1991
and 1994, respectively).
Barium
34. Barium occurs in nature as a divalent cation in combination with other
elements. The two most prevalent naturally occurring barium ores are barium
sulphate and barium carbonate36. Barium sulphate is present in soils but only a
limited amount accumulates in plants. The main route of exposure to barium
compounds for the general population is oral intake via drinking water and food, with
food being the primary source36. Where barium levels in water are high, associated
10
with groundwater of low pH, drinking water may contribute significantly to barium
intake27. No data are available on levels of barium in drinking water in the UK.
35. Case reports indicated that in humans, intentional or accidental ingestion of
barium can cause gastroenteritis, hypokalaemia and hypertension. The WHO
considered that the critical end-points for deriving a TDI for barium are hypertension
and impaired renal function36. Hypertensive effects have been observed in humans
who ingested acute high doses of barium compounds and in workers who inhaled
barium carbonate and dusts of barium ores. Hypertension has also been reported in
rats exposed to barium chloride in drinking-water for 1 month at an estimated daily
dose of 7.1 mg barium/kg body weight. Drinking water studies in rats and mice also
indicated the kidney to be a sensitive target organ, with a lowest identified NOAEL of
45 mg/kg body weight in female rats given barium chloride in drinking water for 2
years. The WHO identified a NOAEL of 0.21 mg barium/kg body weight/day from a
10-week experimental study in humans (barium chloride in drinking water up to 10
mg/L) and an epidemiological study in populations living in communities with mean
drinking water barium concentrations of 0.1 and 7.3 mg/L. Blood pressures were not
significantly affected by barium exposure in either study. Applying an uncertainty
factor of 10 to the NOAEL to allow for database deficiencies and differences between
adults and children resulted in derivation of a TDI of 20 μg/kg body weight36. The
WHO assigned medium confidence to this tolerable intake because neither study
identified a LOAEL, and noted that there were uncertainties about the most sensitive
toxic end-point in humans, and about whether there were differences in toxicity or
toxicokinetics between adults and children.
37. As with the results from 1994, the highest levels of barium in the 2006 survey
were reported in nuts (131 mg/kg) and bread (0.81 mg/kg). All other foodstuffs
contained lower levels than in bread. Levels of barium in nuts were double those
reported in 1994 (131 mg/kg and 56 mg/kg, respectively).
Estimated average
population dietary exposures to barium have increased by approximately 46% since
the last TDS in 1994.
