Number 62 May 1995
MAFF UK - MULTI ELEMENT ANALYSIS OF INFANT FOODS
Index to MAFF UK Food Surveillance Information
Sheets, 1995
See also:
93: MAFF,UK - Multi element
analysis of infant foods - follow-up survey (August 1996)
146: MAFF UK - Concentrations of
metals and other elements in selected snack and convenience foods (March
1998)
167: MAFF UK - Plant Oestrogens in
Soya-Based Infant Formulae (November 1998)
168: MAFF UK - Phthalates in
Infant Formulae - Follow-Up Survey (December 1998)
190: MAFF UK - Metals and other
elements in infant foods (November 1999)
Background
In the light of recent interest in the possible role of the metal
antimony in Sudden Infant Death Syndrome (cot death) and the limited data
available on trace element concentrations in infant foods, MAFF has
undertaken a multi-element survey of breast milk, infant formulae and baby
foods to establish infant exposure to this and other elements from the
diet. A total of 50 samples of baby food, infant food, and milk were
obtained and analysed for eight trace elements. The elements were
antimony, arsenic, chromium, indium, molybdenum, thallium, titanium and
vanadium. These elements are naturally present in food from geochemical
and also from industrial emissions. This survey was initiated as part of
more general surveillance which would allow concentrations of these
elements in the food chain to be assessed. It is hoped that a further
survey on fruit and vegetables will be undertaken in the future.
A sampling plan was devised for 50 samples, including 20 milks (three of
which were breast milk) and milk products and 30 food products. Retail
samples were purchased according to the manufacturers percentage market
share from a range of outlets (e.g. supermarkets, chemists etc.) and were
selected to include all types of packaging currently used by retailers.
The three breast milk samples were obtained as freeze dried samples from
another MAFF-funded project and used to provide an indication of exposure
to these trace elements by breast fed infants.
All samples were prepared according to the manufacturers instructions
prior to analysis as appropriate. The use of boiled tap water for sample
preparation will have contributed to the elemental concentrations found
for each sample, therefore the analytical results should not be regarded
solely as a measure of the product element concentrations but also the
water used in preparation. Samples were dissolved in a mixture of mineral
acids and analysed using either inductively coupled plasma-mass
spectrometry (ICP-MS) or ICP-atomic emission spectrometry (ICP-AES).
Antimony, molybdenum, indium and thallium were measured using ICP-MS and
chromium, vanadium and titanium concentrations were measured using
ICP-AES. Hydride generation ICP-AES was used to obtain accurate
determinations of arsenic. Appropriate analytical quality assurance
measures were taken throughout the analyses, these included duplicate
analyses, the use of certified reference materials and samples spiked with
analytes of a known concentration. The accuracy and precision of the
methods used are acceptable and the estimated measurement uncertainty for
values significantly above the limit of detection was approximately ±20
per cent.
Results
The analytical results obtained from this survey are summarised in
Table 1. For each element the results for the
products which were purchased ready-to-feed and those which required
reconstituting are given separately owing to the different limits of
detection (LOD) attained. The differing LOD result from the different
methods of sample preparation used for the two food types. The results for
the foods analysed have been sub-divided into four groups: vegetable, meat
and cereal products and desserts. The limits of detection attained for
each food group are indicated in the table.
Antimony
All milk samples analysed as part of this survey contained very low
antimony concentrations, most of which were below the LOD [0.5 µg/kg].
Just four of the 22 samples analysed contained concentrations above the
LOD and none of these exceeded 1 µg/kg. Antimony concentrations in
the remaining foods were all low and ranged between the LOD and 32 µg/kg.
Of the 33 foods analysed all but four contained concentrations less than 3
µg/kg.
A previous MAFF funded survey of 24 infant duplicate diets 1
published in 1985 reported a mean antimony concentration of 50 µg/kg
in the diets. Although the antimony concentrations reported for this
current study are significantly lower than those found for the previous
survey this is most probably due to the lower LOD achieved, 0.5-1.0 µg/kg
compared with 20 µg/kg previously.
Arsenic
The arsenic concentrations reported for the milk products surveyed were
all low, at or below the LOD. Of the remaining foods analysed, only six
contained concentrations above the LOD and all of these were less than 14
µg/kg. These results are in keeping with previous surveillance data,
which indicate that mean arsenic concentrations in the diet, determined as
part of the 1991 Total Diet Study (TDS), range between 10 and 40 µg/kg
with the exception of fish which naturally contains high total arsenic
concentrations (but mainly of the non-toxic organic form).
Chromium
Data from the 1991 TDS indicate that chromium concentrations in the diet
are generally around 100 µg/kg (at the LOD), although the
concentrations in the Meat products and the Bread food groups were 3-4
times higher. With the exception of one vegetable product the foods
analysed for this survey contained chromium concentrations of 80 µg/kg
or less which is in keeping with the results of the 1991 TDS. There was no
apparent source of contamination of the one jar of a vegetable product
found to contain 765 µg/kg chromium and examination of the packaging
indicated no visible degradation. The chromium content of this one sample
was undoubtedly high but this result may not be representative of average
chromium concentrations in this product or this type of food. Further
investigations will be undertaken.
Indium
Indium concentrations in the infant milk and the dessert samples
analysed were all less than the LOD for both the ready-to-feed and
reconstituted products (0.1-0.3 µg/kg). The remaining vegetable, meat
and cereal products also contained very low indium concentrations ranging
between the LOD (0.1 and 0.3 µg/kg) and 4.0 µg/kg in one pasta
dish.
These results are unexceptional compared with average indium
concentrations in the similar composite food groups reported for the 1979
TDS which were frequently at the LOD, and ranged between <10 and 50 µg/kg.
Given the reduction in the limits of detection achieved for this more
recent survey, the results for this current survey are probably a more
accurate reflection of the actual levels in the diet.
Molybdenum
Molybdenum is an essential element in man and concentrations of this
element in foods are known to vary considerably. Mean molybdenum
concentrations for the composite food groups in the 1991 TDS ranged from
10 µg/kg in the Fresh fruit and Beverages food groups, up to 1.2
mg/kg in offal.
All infant food samples analysed for this survey contained molybdenum
concentrations above the limits of detection. Milk samples contained the
lowest concentrations, ranging from 0.7 to 1.4 µg/kg in breast milk
samples to 47-65 µg/kg in the soya based milks. The higher molybdenum
concentrations reported for the soya milk products are not unexpected.
Soya milk is vegetable in origin and the results of the 1976 TDS indicated
that the Vegetable food group contained more molybdenum than the Milk
group.
The results for the remaining products varied considerably with
molybdenum concentrations between 20 and 170 µg/kg. Mean molybdenum
concentrations for the different food groups were vegetable products 104 µg/kg;
meat and cereal products; 66 µg/kg each and desserts 56 µg/kg. A
comparison of the molybdenum concentrations observed for these products
and the relevant food groups in the 1991 TDS indicate these results are
typical for the types of food.
Thallium
Thallium concentrations of all infant milk and food products analysed
were low, ranging from below the LOD to 1.3 µg/kg. This is the first
occasion on which MAFF has reported data on thallium concentrations in
baby foods, although mean thallium concentrations of between <10 and <50
µg/kg have previously been observed in the average diet (1979 TDS).
The proportionally lower thallium concentrations reported for these baby
foods compared with previous data on food probably results from the
improved LOD.
Titanium
The titanium concentrations of both the milk samples and other baby food
products were all low and unexceptional. One sample of whey-dominant
infant milk contained a titanium concentration of 20 µg/kg; the
remaining milk samples contained concentrations below the LOD which were 8
and 9 µg/kg respectively for reconstituted and ready-to-feed milks.
All the vegetable, meat, cereal products and desserts contained titanium
concentrations less than the LOD (LOD = 25 µg/kg for reconstituted
products and 50 µg/kg for read-to-feed products). There is no
available MAFF generated surveillance data with which to compare the
results of this survey.
Vanadium
Vanadium concentrations were low for all samples analysed and frequently
at the limit of detection. The highest concentration recorded was 60 µg/kg
in one fruit cereal product, all remaining cereal dishes contained
vanadium concentrations below the LOD. This is the first occasion that the
Ministry has analysed food for vanadium.
Interpretation
The results of this survey are generally reassuring. Antimony
concentrations reported for the foods analysed for this survey indicate
that exposure of infants to antimony from the diet is very low. The infant
milk and foods analysed were found to contain only very low concentrations
of the elements arsenic, chromium, indium, molybdenum, thallium, titanium
and vanadium. In many cases the concentrations reported were less than
their respective limits of detection. Frequently the trace element
concentrations of foods analysed for this survey were lower than found in
previous surveillance. This probably resulted from the lower limits of
detection achieved by use of improved analytical techniques rather than an
actual reduction in the content of the foods analysed.
One sample of a vegetable based infant food was found to contain a high
chromium concentration, but the sample size of this survey was small and
hence the chromium concentration of this product may not be representative
of the product generally. Previous surveillance data1
on chromium indicate that concentrations such as these can occur in both
fruit and vegetables. Nevertheless it is prudent to analyse further
samples of this product to determine whether they are similarly effected,
and the results of these analyses will be published in the Information
Bulletin as soon as they are available.
References:
- Food Surveillance Paper No. 15, Survey of
aluminium, antimony, chromium, cobalt, indium, nickel, thallium and tin
in food. HMSO (ISBN 0 11 242740 5).
Contact point
Dr Gillian Ysart
MAFF, Joint Food Safety and Standards Group
Food Contaminants Division
Rm 238, Ergon House
c/o Nobel House
17 Smith Square
London, SW1P 3JR.
Tel: (+44) (0)20 7238 5756
Fax: (+44) (0)20 7238 5331
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