Number 123 August 1997
MAFF UK - DIOXINS AND PCBS IN COWS' MILK FROM FARMS CLOSE TO INDUSTRIAL
SITES: 1996 SURVEY RESULTS
Index to MAFF UK Food Surveillance Information
Sheets, 1997
See also:
19: MAFF, UK: Dioxins in Cows' Milk
(November 1993)
43: MAFF, UK:
Dioxins in Cows' Milk (October 1994)
44: MAFF, UK: Contaminants in Cows' Milk from
the Clitheroe Area (October 1994)
75:
MAFF UK - Dioxins in Cows' Milk from the Bolsover Area (November 1995)
100: MAFF UK - Dioxins in Cows' Milk from
farms close to Industrial Sites (January 1997)
107: MAFF, UK - Dioxins and PCBs in Cows
Milk from Farms Close to Industrial Sites (June 1997)
120: MAFF, UK - Dioxins in Cows' Milk from
Northern Ireland (August 1997)
124:
MAFF UK - Dioxins and PCBs in Cows' Milk from the Bolsover Area (August 1997)
133: MAFF, UK- Dioxins and PCBs in Cows'
Milk from farms close to Industrial Sites: Rotherham 1997 (November 1997)
134: MAFF, UK- Dioxins and PCBs in Cows'
Milk from the Bolsover Area - October 1997 (November 1997)
135: MAFF, UK- Dioxins and PCBs in Cows'
Milk from farms close to Industrial Sites: Huddersfield 1997 (November 1997)
136: MAFF, UK- Dioxins and PCBs in Retail
Cows' Milk in England (December 1997)
143: MAFF UK - Dioxins and PCBs in Cows'
Milk from the Bolsover Area Collected in October and November 1997 (March 1998)
145: MAFF UK - Dioxins and PCBs in Farmed
Trout in England and Wales (March 1998)
184: MAFF UK - Dioxins and PCBs in UK and
Imported Marine Fish (August 1999)
Summary
MAFF has, since 1993, carried out an annual survey of dioxins and
polychlorinated biphenyls (PCBs) in samples of cows' milk from individual farms
in the vicinity of potential industrial sources of these chemicals. Data for
samples of milk collected from 1993-1995 have already been published.1 This paper presents the results for samples collected
in 1996.
The combined concentrations of PCBs and dioxins, expressed as Toxic
Equivalents (TEQs), in milk samples were below the Maximum Tolerable
Concentration (MTC) set by MAFF and the Department of Health of 16.6 ng TEQ/kg
milk fat or 0.66 ng TEQ/kg whole milk. These results do not indicate the
existence of a public health risk.
Background
Dioxins and PCBs are very persistent chemicals which are ubiquitous in the
environment and so are generally present in very low concentrations in foods,
especially fat-containing foods including cows' milk. Further background
information on dioxins and PCBs can be found in Food Surveillance Information
Sheets Nos. 105,2 106 3
and 107.1
Analytical results for dioxins and PCBs are expressed in terms of Toxic
Equivalents (TEQs), which have been explained in detail in Food Surveillance
Information Sheet No. 105.2 This allows an
assessment of the toxicological significance of the complex mixtures of dioxin
and PCB congeners in cows' milk.
The total concentrations of dioxins and PCBs found in milk are compared with
the Maximum Tolerable Concentration (MTC) of 16.6 ng TEQ/kg milk fat.1,4 The MTC is an assessment by
scientists in MAFF and the Department of Health of the highest concentration of
PCBs and dioxins that could be present in milk and yet not result in a high
level (97.5 percentile) consumer of milk exceeding the Tolerable Daily Intake
(TDI) of 10 pg 2,3,7,8-TCDD/kg bodyweight/day. 4,5,6
MAFF has been conducting surveys for dioxins in food since 1989, including
milk samples from farms in urban/industrialised areas.4
Since 1993, MAFF has also been collecting samples of milk from farms in the
vicinity of industrial sites throughout England. These industrial sites have
included waste incinerators, coal-fired power stations and cement kilns, which
are all potential sources of dioxins and PCBs. All samples are analysed for the
17 dioxin congeners of toxicological significance. Following recent
developments in analytical methodology, it is now also possible to quantify
virtually every one of the possible 209 PCB congeners. However, such analysis
would be prohibitively costly so specific congeners are selected for analysis,
including those which are toxicologically significant and some congeners
reported to occur in food or human milk.2
Samples were collected in 1996 from 26 farms in the vicinity of 7 industrial
sites. These sites included secondary metal refiners, a precious metals
refiner, a recycling plant, a steel works and a municipal waste incinerator.
Methods
The analytical methodology for determining dioxin and PCB concentrations in
cows' milk has been reported previously.7
All samples were analysed by high resolution gas chromatography-high
resolution mass spectrometry (GC-MS) at CSL Food Science Laboratory, Norwich.
The laboratory has participated in inter-laboratory trials of measurement of
dioxins and PCBs in human milk and human blood organised by the World Health
Organisation and has recognised expertise in the analysis of foods for dioxins
and PCBs.
The coefficient of variation for the analytical data is a measure of the
difference that may be expected between individual analyses of the same sample.
Based on other work, the coefficients of variation for the analysis of milk were
approximately 10 per cent for dioxins and non-ortho-PCBs and up to 5
per cent for ortho-PCBs.
Results
This report presents the individual and combined results for dioxins and
PCBs in cows' milk samples collected in 1996. The concentrations of dioxins and
PCBs found in the samples from the various sites are summarised in
Table 1. The data for dioxin and PCB levels in cows'
milk from farms in the Huddersfield area have already been reported.1
In summary, the results for the 1996 samples were:
- Dioxin concentrations were in the range 0.81-8.1 ng TEQ/kg milk fat.
- PCB concentrations were in the range of 1.2-8.0 ng TEQ/kg milk fat.
- The combined dioxin and PCB concentrations were in the range 1.3-16.1 ng
TEQ/kg milk fat.
Full congener specific data are available on request.
Interpretation
The combined concentrations of dioxins and PCBs in all samples of milk
tested were below the Maximum Tolerable Concentration (MTC) set by MAFF and the
Department of Health of 16.6 ng TEQ/kg milk fat. These results do not indicate
the existence of a public health risk.
Concentrations of dioxins and PCBs in any one sample of milk will include
contributions from a mixture of industrial, domestic and disperse sources, such
as road traffic. In 23 of the 26 samples the concentrations of dioxins in the
milk were within the anticipated range based on previous survey results for
dioxins in cows' milk from farms in rural/urban areas (1.1-7.1 ng TEQ/kg milk
fat).4 However, three of the samples contained
dioxins at higher concentrations, although the combined dioxin and PCB
concentrations in these samples were still below the MTC. Two samples were from
farms in the Huddersfield area and data on the concentration of dioxins and PCBs
in these cows' milk samples have already been published in Food Surveillance
Information Sheet No. 107.1
The third sample came from a farm in the Rotherham area. Steel works are a
potential source of dioxins emissions, and the Rotherham area was selected for
sampling because of the presence of several steels works. However, a number of
other industrial processes also operate in the area, and it is not possible to
determine the contribution of any one steels works or any other specific
emissions source(s) to the total concentrations of dioxins and PCBs found in the
milk from this farm.
MAFF has informed interested parties including the relevant local
authorities, farmers and the National Farmers Union about the results for
Huddersfield and Rotherham. MAFF is also currently discussing its plans for
further investigations with the relevant local authorities for these areas and
the Environment Agency. Further samples have been collected this year to
determine if the elevated concentrations of dioxins and PCBs are persisting in
the cows' milk produced in the Huddersfield and Rotherham areas and to ensure
that levels of these contaminants in milk entering the food supply remain below
the MTC.
The concentrations of dioxins and PCBs in cows' milk reported here are
consistent with data produced by similar surveys in the UK and Europe.1,8
References
- Ministry of Agriculture, Fisheries and Food (1997)
Dioxins and PCBs in Cows' Milk from Farms Close to Industrial Sites. Food
Surveillance Information Sheet No. 107, MAFF, London
- Ministry of Agriculture, Fisheries and Food (1997)
Dioxins and Polychlorinated Biphenyls and Foods and Human Milk. Food
Surveillance Information Sheet No. 105, MAFF, London.
- Ministry of Agriculture, Fisheries and Food (1997)
Dioxins and Polychlorinated Biphenyls in Fish Oil Dietary Supplements. Food
Surveillance Information Sheet No. 106, MAFF, London.
- Ministry of Agriculture, Fisheries and Food (1992)
Dioxins in Food. Food Surveillance Paper No. 31, publ. HMSO.
- World Health Organisation, Regional Office for Europe
(1991) Summary report. Consultation on Tolerable Daily Intake from food of PCDDs
and PCDFs. Bilthoven, Netherlands, 4-7 December 1990. EUR/ICP/PCS 030(S) 0369n,
publ. WHO Regional Office for Europe, Copenhagen.
- Statement by the Committee on Toxicity of Chemicals in
Food, Consumer Products and the Environment on the US EPA draft health
assessment document for 2,3,7,8-tetrachlorodibenzo-p-dioxin and related
compounds (1995).
- Krokos, F., Creaser, C.S., Wright, C. and Startin,
J.R. (1997) Congener-specific method for the determination of ortho- and
non-ortho polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins
and polychlorinated dibenzofurans in foods by carbon-column fractionation and
gas chromatography-isotope dilution mass spectrometry. Fresenius Journal of
Analytical Chemistry, 357, 732-742.
- Ministry of Agriculture, Fisheries and Food (1997)
Dioxins in Cows' Milk from Farms Close to Industrial Sites. Food
Surveillance Information Sheet
No. 100, MAFF, London
Contact Point
For further information, please contact:
Dr Nigel Harrison
Food Contaminants Division
Ergon House, c/o Nobel
House
17 Smith Square
London SW1P 3JR
Tel: +44 (0) 171 238 6235
Fax: +44 (0) 171 238 5331
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