Number 124 August 1997
MAFF UK - DIOXINS AND PCBS IN COWS' MILK FROM THE BOLSOVER AREA
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)
123:
MAFF, UK- Dioxins and PCBs in Cows' Milk from farms close to Industrial Sites:
1996 Survey Results (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 monitored the levels of dioxins in cows' milk from farms in the
Bolsover area of Derbyshire each year since 1991.1,2,3,4,5,6,7 Samples
of milk collected since 1994 were also analysed for selected congeners of
polychlorinated biphenyls (PCBs), using recently developed analytical methods.
Since 1991, the concentration of dioxins in milk from farms in the Bolsover
area have generally been declining, but increased in 1996. Concentrations of
PCBs in the latest samples are also higher than those found in the 1995 samples.
The combined dioxin and PCB concentration in milk from Farm B continues to
be in excess of the Maximum Tolerable Concentration (MTC), but this farm runs a
suckler herd and does not produce milk for human consumption.
The combined dioxin and PCB concentration in milk from Farm F does not
exceed the MTC and there is no risk to public health from consumption of milk
produced by this farm. In addition, the concentration of dioxins alone falls
within the range expected from previous surveys (1.1-7.1 ng TEQ/kg milk fat).
This farm stopped producing milk for human consumption in November 1996.
MAFF has met with representatives of the Environment Agency and the local
authority to discuss possible reasons for this increase in the concentration of
dioxins in milk sampled from the Bolsover area in 1996. No obvious explanation
for the change was identified, but it was agreed that further investigations
were necessary.
Further cows' milk samples were collected in July 1997, in collaboration
with local Environmental Health Officers, from Farms B and F as well as from
other dairy farms in the area to investigate further the current findings and to
ensure that levels in milk entering the human food supply remain below the MTC.
Background
Dioxins and PCBs are very stable, ubiquitous chemicals in the environment
and 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. 105,8 106 9 and 107.10
The results are expressed in terms of Toxic Equivalents (TEQs), which have
been explained in detail in the Food Surveillance Information Sheet No. 105.8 This allows an assessment of the toxicological
significance of the complex mixtures of dioxin and PCB congeners in cows' milk.
The total TEQ concentrations of dioxins and PCBs found in milk are compared
with the Maximum Tolerable Concentration (MTC) of 16.6 ng TEQ/kg milk fat.1,10 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 TEQ/kg bodyweight/day.1,11,12
MAFF has been conducting surveys for dioxins in food since 1989, including
in milk samples from farms in urban/industrialised areas.1
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.8
In 1989-90, MAFF collected samples of cows' milk from farms in various rural
and urban/industrialised areas for dioxin analysis.1
One relatively industrialised area chosen was Bolsover in Derbyshire. That
study, and subsequent work, revealed that samples of milk taken from three farms
(Farms A, B and C) in the vicinity of a chemical waste incinerator and a
smokeless fuels plant exceeded the MTC for dioxins in cows milk. Levels of
dioxins in milk from the other farms sampled, from dairies and from retail milk
sold in the area were all below the MTC.
Seven samples were collected in 1994, two from Farm A, two from Farm B and
one each from Farms F, G and H.6 Four samples
were collected in 1995, two from Farm B and one each from Farms F and H, as Farm
G was no longer in milk production.7
Samples were collected from two farms in the Bolsover area in 1996, Farm B
and Farm F, as Farm H was no longer in milk production. One sample of milk was
taken from each of four cows on Farm B and one sample of milk was taken from a
bulk milk tank on Farm F.
Methods
The analytical methodology for determining dioxin and PCB concentrations in
cows' milk has already been reported.13
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 latest data on dioxins and PCBs in cows' milk
samples collected from farms in Bolsover in 1996 as well as the recently
determined PCB concentration in cows' milk collected in 1994 and 1995. Total
concentrations of dioxins and PCBs found in the milk taken from farms in the
Bolsover area are summarised in Table 1. This table
includes all data collected during monitoring of milk from the area to give a
historical perspective. Full congener specific data are available on request.
Interpretation
Since 1991 the concentrations of dioxins in milk from farms in the Bolsover
area have generally been declining, but in 1996 concentrations have risen to
levels approaching those found in 1991. Concentrations of PCBs in the latest
samples are also elevated compared with the previous year.
The combined dioxin and PCB concentration in milk from Farm B continues to
be in excess of the Maximum Tolerable Concentration (MTC), but this farm runs a
suckler herd and does not produce milk for human consumption. The milk fat
contents of the samples were very low (0.2-1.2 per cent milk fat) in comparison
with milk from dairy cows (~ 4 per cent milk fat).
Milk from Farm F also contained increased levels of dioxins and PCBs in 1996
compared with recent years. However, the combined concentration of these
chemicals does not exceed the MTC and there is no risk to public health from
consumption of milk and milk products produced by this farm. In addition, the
concentration of dioxins alone falls within the range expected from previous
surveys (1.1-7.1 ng TEQ/kg milk fat). Farm F has since ceased producing milk
for human consumption.
Although the levels of dioxins and PCBs in milk from these samples does not
raise a food safety concern, the rise in concentrations in 1996 was unexpected.
MAFF has met with representatives of the Environment Agency and with the local
authority to discuss possible reasons for this increase in the concentration of
dioxins in milk sampled from the Bolsover area in 1996. The incinerator
previously implicated in elevated levels of dioxins in the area has been unused
since 1991. It was concluded that there was no obvious explanation and that
further investigations were necessary.
Further cows' milk samples were collected in July 1997, in collaboration
with local Environmental Health Officers, to investigate further the current
findings and to ensure that levels in milk entering the human food supply remain
below the MTC. These samples were obtained from Farms B and F and from other
dairy farms in the area. These other farms included some not sampled for some
time and some which had not previously been sampled.
References
- Ministry of Agriculture, Fisheries and Food (1992)
Dioxins in Food. Food Surveillance Paper No. 31, publ. HMSO.
- Ministry of Agriculture, Fisheries and Food (1992)
Report of Studies on Dioxins in Derbyshire carried out by the Ministry of
Agriculture, Fisheries and Food.
- Ministry of Agriculture, Fisheries and Food (1992)
Further Report of Studies on Dioxins in Derbyshire carried out by the Ministry
of Agriculture, Fisheries and Food.
- Ministry of Agriculture, Fisheries and Food (1992)
Third Report of Studies on Dioxins in Derbyshire carried out by the Ministry of
Agriculture, Fisheries and Food.
- Ministry of Agriculture, Fisheries and Food (1993)
Dioxins in Cows'Milk.
Food Surveillance Information Sheet No. 19, MAFF, London
- Ministry of Agriculture, Fisheries and Food (1994)
Dioxins in Cows' Milk.. Food Surveillance Information Sheet No. 43,
MAFF, London.
- Ministry of Agriculture, Fisheries and Food (1995)
Dioxins in Cows' Milk from the Bolsover Area. Food Surveillance Information
Sheet No. 75, MAFF, London.
- Ministry of Agriculture, Fisheries and Food (1997)
Dioxins and Polychlorinated Biphenyls in 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 (1997)
Dioxins and PCBs in Cows' Milk from Farms Close to Industrial Sites. Food
Surveillance Information Sheet No. 107, MAFF, London
- 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.
Further information
For further information, please contact:
Dr Nigel Harrison
MAFF, Food Safety and Standards Group
Food
Contaminants Division
Room 234
Ergon House
17 Smith Square
London
SW1P 3JR
Tel: +44 (0) 171 238 6235
Fax: +44 (0) 171 238 5331
Return to Index to Surveillance Information Sheets, 1997 page
Go to top of page
These pages were last updated on 31st July 1997
