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On Pesticides, Agricultural Chemicals, Veterinary Drugs, Environmental Pollutants
and Other Impurities in Agri-Food Commodities of Animal Origin

Dioxin Annex

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Dioxins, furans and PCBs

Background Information

Dioxin refers to a group of compounds with similar chemical and biological characteristics. Hundreds of these toxic compounds exist. Other compounds, related to chlorinated dibenzo-p-dioxin are frequently included in the discussion of the toxic effects of "dioxins". These compounds include chlorinated dibenzofurans and certain polychlorinated biphenyls (PCB). These compounds (dioxins and furans) are not created intentionally but rather form as an inadvertent result of human activities and by natural processes. PCBs were man-made, but are no longer produced.

Sources and distribution

Dioxins are released into the air from combustion processes such as waste incineration and from burning fuels. They can also be formed from chlorine bleaching of pulp and paper, manufacturing, industrial activity and during forest fires. Government and industry efforts have reduced dioxin emissions over the past decades, but because dioxins are persistent pollutants they continue to exist in the environment. While the larger portion of current background dioxin exposure is attributable to man made sources and releases over several decades, low levels from natural sources would continue even if all man made sources were eliminated.

When released into the air, dioxins are transported long distances from their initial source, (see www.cec.org/files/PDF/POLLUTANTS/dioxrep_EN.pdf ) and because of this are found around the world. In water releases settle into sediments where they can be further transported or ingested by fish. Dioxins break down very slowly and can be deposited on plants and taken up by animals and aquatic organisms. In animals, dioxins bio-accumulate in the fat and fatty tissues.

Health concerns and human exposure

Dioxins have been shown to cause a number of adverse health effects. Due to their ubiquitous distribution in the environment, all humans will have been exposed to some levels of dioxin. The health effects associated with dioxins depend on a variety of factors, including the level of exposure, when someone was exposed, and how long and how often. Chloracne is the most notable effect on individuals that have experienced exposure to large quantities of dioxin. Chloracne is a skin disease manifested by severe acne like lesions. Also evident are rashes, liver damage and skin discolouration.

Studies show that individuals exposed to dioxins over many years have an increased risk of cancer. In animals an increased risk of cancer occurs from long term low exposure to dioxins.

The USEPA has indicated that "Most of the population has low level exposure to dioxins. EPA estimates that most dioxin exposure occurs through the diet, with over 95% coming through dietary intake of animal fats. Small amounts of exposure occur from breathing air containing trace amounts of dioxins on particles and in vapor form, from inadvertent ingestion of soil containing dioxins, and from absorption through the skin contacting air, soil, or water containing minute levels. Some people may have higher exposures than the general population. They may have experienced elevated exposures to dioxins as a result of particular food contamination incidents, through workplace exposures, from industrial accidents, or from consumption of unusually high amounts of fish, meat, or dairy products containing elevated levels of dioxins."

Source: http://cfpub.epa.gov/ncea/cfm/dioxin.cfm?ActType=default

Toxicity:

The most toxic forms of dioxin are 2,3,7,8-tetrachloro dibenzo-p-dioxin and 1,2,3,7,8-pentachloro dibenzo-p-dioxin. Scientists use a shorthand method for comparing the toxicity of different types or mixtures of dioxins to the toxicity of  2,3,7,8-tetrachloro dibenzo-p-dioxin and 1,2,3,7,8-pentachloro dibenzo-p-dioxin. This method is called the "Toxicity Equivalence" or TEQ. Toxic Equivalency Factors (TEF) have been attributed to specified congeners. There remain some small differences in the assigned TEF (WHO and NATO) for the various congeners.

http://www.hygiene.ruhr-uni-bochum.de/hygiene/dioxin/dioxin-information.html
http://www.cqs.com/epa/exposure/

The TEF used by the Canadian Food Inspection Agency’s National Chemical Residue Monitoring Program were transmitted to the Agency via a private communication from Health Canada during the Belgian Dioxin Crisis in the summer of 1999. These TEFs are indicated in Table 1 following:

Table 1: Toxic Equivalency Factors for dioxins and dioxin like compounds

CHLORINATED DIBENZODIOXINS TEF
2,3,7,8-TCDD 1.0
1,2,3,7,8-PeCDD 1.0
1,2,3,4,7,8-HxCDD 0.1
1,2,3,6,7,8-HxCDD 0.1
1,2,3,7,8,9-HxCDD 0.1
1,2,3,4,6,7,8-HpCDD 0.01
1,2,3,4,6,7,8,9-OCDD 0.0001
CHLORINATED DIBENZOFURANS  
2,3,7,8-TCDF 0.1
1,2,3,7,8-PeCDF 0.05
2,3,4,7,8-PeCDF 0.5
1,2,3,4,7,8-HxCDF 0.1
1,2,3,6,7,8-HxCDF 0.1
1,2,3,7,8,9-HxCDF 0.1
2,3,4,6,7,8-HxCDF 0.1
1,2,3,4,6,7,8-HpCDF 0.01
1,2,3,4,7,8,9-HpCDF 0.01
1,2,3,4,6,7,8,9-OCDF 0.0001
PCBs with toxic equivalency factors  
3,3',4,4'-TeCB (PCB 77) 0.0001
3,4, 4',5-TeCB (PCB 81) 0.0001
2,3,3',4,4'-PeCB (PCB 105) 0.0001
2,3,4,4',5-PeCB (PCB 114) 0.0005
2,3',4,4',5-PeCB (PCB 118) 0.0001
2',3,4,4',5-PeCB (PCB 123) 0.0001
3,3',4,4',5-PeCB (PCB 126) 0.1
2,3,3',4,4',5-HxCB (PCB 156) 0.0005
2,3,3',4,4',5'-HxCB (PCB 157) 0.0005
2,3',4,4',5,5'-HxCB (PCB 167) 0.00001
3,3',4,4',5,5'-HxCB (PCB 169) 0.01
2,2',3,3',4,4',5-HpCB (PCB 170) 0 previously 0.0001*
2,2',3,4,4',5,5'-HpCB (PCB 180) 0 previously 0.00001*
2,3,3',4,4',5,5'-HpCB (PCB 189) 0.0001

* Toxic Equivalence Factor are based upon WHO/97 estimates except for the congener PCB 170 and PCB 180 which are based upon WHO/94 estimated toxicity factors.

In addition to the polychlorinated biphenyls listed in Table 1 (above) the CFIA’s NCRMP also tests the samples for total polychlorinated biphenyls PCB. This testing is for the sum of all congeners identified as PCBs but includes a scope not less than the congeners listed in Table 2, below

Table 2: PCB congeners included in the NCRMP

Number Congener Number Congener
PCB #001 2-Chlorobiphenyl PCB #128 2,2',3,3',4,4'-Hexachlorobiphenyl
PCB #003 4-Chlorobiphenyl PCB #129 2,2',3,3',4,5-Hexachlorobiphenyl
PCB #004 2,2'-Dichlorobiphenyl PCB #137 2,2',3,4,4',5-Hexachlorobiphenyl
PCB #008 2,4'-Dichlorobiphenyl PCB #138 2,2',3,4,4',5'-Hexachlorobiphenyl
PCB #010 2,6-Dichlorobiphenyl PCB #141 2,2',3,4,5,5'-Hexachlorobiphenyl
PCB #015 4,4'-Dichlorobiphenyl PCB #149 2,2',3,4,5',6-Hexachlorobiphenyl
PCB #018 2,2',5-Trichlorobiphenyl PCB #151 2,2',3,5,5',6-Hexachlorobiphenyl
PCB #019 2,2',6-Trichlorobiphenyl PCB #153 2,2',4,4',5,5'-Hexachlorobiphenyl
PCB #022 2,3,4'-Trichlorobiphenyl PCB #155 2,2',4,4',6,6'-Hexachlorobiphenyl
PCB #028 2,4,4'-Trichlorobiphenyl PCB #156 2,3,3',4,4',5-Hexachlorobiphenyl
PCB #033 2',3,4'-Trichlorobiphenyl PCB #157 2,3,3',4,4',5'-Hexachlorobiphenyl
PCB #037 3,4,4'-Trichlorobiphenyl PCB #158 2,3,3',4,4',6-Hexachlorobiphenyl
PCB #040 2,2',3,3'-Tetrachlorobiphenyl PCB #167 2,3',4,4',5,5'-Hexachlorobiphenyl
PCB #041 2,2',3,4-Tetrachlorobiphenyl PCB #168 2,3',4,4',5',6-Hexachlorobiphenyl
PCB #044 2,2',3,5-Tetrachlorobiphenyl PCB #169 3,3',4,4',5,5'-Hexachlorobiphenyl
PCB #049 2,2',4,5'-Tetrachlorobiphenyl PCB #170 2,2',3,3',4,4',5-Heptchlorobiphenyl
PCB #052 2,2',5,5'-Tetrachlorobiphenyl PCB #171 2,2',3,3',4,4',6-Heptchlorobiphenyl
PCB #054 2,2',6,6''-Tetrachlorobiphenyl PCB #177 2,2',3,3',4',5,6-Heptchlorobiphenyl
PCB #060 2,3',4,4'-Tetrachlorobiphenyl PCB #178 2,2',3,3',5,5',6-Heptchlorobiphenyl
PCB #066 2,3',4,4'-Tetrachlorobiphenyl PCB #180 2,2',3,4,4',5,5'-Heptchlorobiphenyl
PCB #070 2,3',4',5-Tetrachlorobiphenyl PCB #183 2,2',3,4,4',5',6-Heptchlorobiphenyl
PCB #074 2,4,4',5-Tetrachlorobiphenyl PCB #187 2,2',3,4',5,5',6-Heptchlorobiphenyl
PCB #077 3,3',4',4'-Tetrachlorobiphenyl PCB #188 2,2',3,4',5,6,6'-Heptchlorobiphenyl
PCB #081 3,4,4',5-Tetrachlorobiphenyl PCB #189 2,3,3',4,4',5,5'-Heptchlorobiphenyl
PCB #087 2,2',3,4,5'-Pentachlorobiphenyl PCB #191 2,3,3',4,4',5',6-Heptchlorobiphenyl
PCB #095 2,2',3,5',6-Pentachlorobiphenyl PCB #193 2,3,3',4',5,5',6-Heptchlorobiphenyl
PCB #099 2,2',4,4',5-Pentachlorobiphenyl PCB #194 2,2',3,3',4,4',5,5'-Octachlorobiphenyl
PCB #104 2,2',4,6,6'-Pentachlorobiphenyl PCB #199 2,2',3,3',4,5,6,6'-Octachlorobiphenyl
PCB #105 2,3,3',4,4'-Pentachlorobiphenyl PCB #201 2,2',3,3',4,5,5',6'-Octachlorobiphenyl
PCB #110 2,3,3',4',6'-Pentachlorobiphenyl PCB #202 2,2',3,3',5,5',6,6'-Octachlorobiphenyl
PCB #114 2,3,4,4',5-Pentachlorobiphenyl PCB #203 2,2',3,4,4',5,5',6-Octachlorobiphenyl
PCB #118 2,3',4,4',5-Pentachlorobiphenyl PCB #205 2,3,3',4,4',5,5',6-Octachlorobiphenyl
PCB #119 2,3',4,4',6-Pentachlorobiphenyl PCB #206 2,2',3,3',4,4',5,5',6-Nonachlorobiphenyl
PCB #123 2',3,4,4',5-Pentachlorobiphenyl PCB #208 2,2',3,3',4,5,5',6,6'-Nonachlorobiphenyl
PCB #126 3,3',4,4',5-Pentachlorobiphenyl PCB #209 Decachlorobiphenyl

Legal Authority

Paragraph 4 (d) of the Food and Drug Act Describes the following prohibition on the sale of food in Canada " No person shall sell an article of food that is adulterated" (see page VIII). Furthermore the Food and Drug Regulations

In section B.01.046 (1) describe the following description for "adulteration" as the condition pertains to dioxins:

"A food is adulterated if any of the following substances or classes of substances are present therein or have been added there to:" - Item (p) on the list is chlorinated dibenzo-p-dioxins.

The impact of this regulation is to render illegal the sale of an item, as food, if it contains any portion of chlorinated dibenzo-p-dioxins. (B.01.047 section (f) creates an exemption for fish that contains 20 parts per trillion or less of 2,3,7,8-tetrachloro-dibenzo-p-dioxin.)

The CFIA has requested that Health Canada re-evaluate the dioxin standards as they apply to foods other than fish. Health Canada has indicated that standards for dioxin and dioxin like compounds in food are currently under review.

In the interim the CFIA has initiated a follow up program wherein farms/producers presenting animals found with elevated levels of dioxins during monitoring are subject of additional follow up inspection activities. The aim is to identify local environmental sources which may have contributed to the elevated initial residue finding. These follow activities are triggered by initial findings for dioxins (excluding dioxin like PCB contribution) which exceed an upper bound limit of 3.5 ppt (TEQ/g fat) and at the same time exceed a lower bound limit of 2.5 ppt.

Results of CFIA residue monitoring for dioxins and dioxin like compounds

Table 3: Portion of samples in violation of current Canadian standard for dioxins

Commodity No. of samples Violations (B.01.046) **
Beef fat 31 29
Buffalo fat 16 15
Chicken fat 37 27
Cow fat 26 17
Raw milk (USA) 1 1
Raw milk 208 198
Horse fat 27 27
Mutton fat 34 22
Pork fat 46 34
Total 426 370

As indicated above – A violation of B.01.046 does not necessarily entail a health risk. The data gathered to date shows low background levels of dioxin in animal-derived products. Health Canada has determined that such trace amounts do not pose a risk to the health of the consumer (Risk Assessment provided to CFIA). The international consensus on safe levels of dioxins in food is under consideration. Canada, the European Union, the United States and the Codex Alimentarius are presently engaged in seeking standards for dioxin contamination of food items.

Table 4: Finding of polychlorinated biphenyls (total PCBs by weight in fat) in units of ng/g of fat

Commodity Number Mean Minimum Maximum Violations
Beef fat 31 2.35 0.264 10.376  
Buffalo fat 16 2.524 0.717 12.870  
Chicken fat 37 2.044 0.11 15.314  
Cow fat 26 2.957 0.54 8.775  
Raw milk (USA) 1 1.394 1.394 1.394  
Raw milk 208 2.426 0.002 24.706  
Horse fat 27 6.088 0.637 29.576  
Mutton fat 34 1.644 0.40 5.154  
Pork fat 46 1.611 0.426 5.50  

 

Current Health Canada guidelines for PCB contamination
0.1 ppm eggs (whole egg less shell)
0.2 ppm meat, beef dairy products (w/w in fat)
0.5 ppm poultry (w/w in fat)

Table 5: Toxic equivalence attributable to dioxins, furans and PCBs

Commodity Mean Minimum Maximum
Lower bound Upper bound Lower bound Upper bound Lower bound Upper bound
Chlorinated dizenzo-p-dioxins (pg TEQ/gram of fat)
Beef fat 0.540 0.738 0.000 0.262 2.420 2.573
Buffalo fat 0.723 0.997 0.000 0.262 6.445 6.545
Chicken fat 0.091 0.327 0.000 0.068 1.741 1.883
Cow fat 0.320 0.540 0.000 0.262 2.313 2.313
Raw milk (USA) 0.185 0.216 0.185 0.216 0.185 0.216
Raw milk 0.155 0.197 0.000 0.027 2.203 2.229
Horse fat 1.993 2.320 0.000 0.293 13.797 13.897
Mutton fat 0.302 0.584 0.000 0.262 3.931 4.860
Pork fat 0.486 0.729 0.000 0.262 11.566 11.666
Chlorinated dibenzofurans (pg TEQ/gram of fat)
Beef fat 0.264 0.391 0.000 0.149 1.894 1.904
Buffalo fat 0.173 0.308 0.000 0.149 1.269 1.356
Chicken fat 0.054 0.196 0.000 0.149 0.521 0.630
Cow fat 0.316 0.460 0.000 0.149 3.729 3.831
Raw milk (USA) 0.076 0.080 0.076 0.080 0.076 0.080
Raw milk 0.049 0.067 0.000 0.017 0.640 0.643
Horse fat 0.407 0.544 0.000 0.149 1.466 1.502
Mutton fat 0.120 0.278 0.000 0.149 2.365 2.365
Pork fat 0.256 0.382 0.000 0.149 6.622 6.637
Polychlorinated biphenyls PCBs (pg TEQ/gram of fat)
Beef fat 0.070 0.140 0.001 0.047 0.310 0.326
Buffalo fat 0.167 0.219 0.010 0.071 1.481 1.501
Chicken fat 0.072 0.272 0.000 0.042 0.486 0.771
Cow fat 0.218 0.373 0.008 0.042 1.261 1.355
Raw milk (USA) 0.078 0.080 0.078 0.080 0.078 0.080
Raw milk 0.189 0.190 0.016 0.023 1.217 1.217
Horse fat 1.033 1.064 0.009 0.048 5.866 5.931
Mutton fat 0.124 0.241 0.001 0.016 2.028 2.029
Pork fat 0.065 0.142 0.000 0.027 0.445 0.468

Table 6: Dioxin total toxic equivalence in selected commodities (pg TEQ/gram of fat)
Values are for the sum of Dioxins, furans and PCBs with TEF

Commodity Mean Minimum Maximum
Lower bound Upper bound Lower bound Upper bound Lower bound Upper bound
Beef fat 0.874 1.270 0.007 0.463 4.383 4.601
Buffalo fat 1.063 1.524 0.037 0.493 7.800 8.002
Chicken fat 0.217 0.795 0.000 0.479 2.278 2.789
Cow fat 0.853 1.373 0.016 0.476 5.873 6.112
Raw milk (USA) 0.339 0.376 0.339 0.376 0.339 0.376
Raw milk 0.393 0.455 0.028 0.113 2.883 2.914
Horse fat 3.432 3.928 0.032 0.554 18.726 18.866
Mutton fat 0.546 1.104 0.006 0.462 5.737 5.841
Pork fat 0.807 1.254 0.000 0.442 18.206 18.390

Lower bound: This represents the mean, minimum and maximum value of all samples for which the congeners found present at levels below their detection limits are represented as being at a level of zero.

Upper bound: This represents the mean, minimum and maximum value of all samples for which the congeners found present at levels below their detection limits are represented as being at a level of their detection limits.

The traditional middle bound limit, which results from the use of one half the detection limit for all non detectable congeners, can be estimated by adding one half the difference between the upper and lower bound limit to the lower bound limit.

References:

http://cfpub.epa.gov/ncea/cfm/dioxin.cfm?ActType=default
http://www.cqs.com/epa/exposure/
http://www.teagasc.ie/research/reports/foodprocessing/5206/eopr-5206.htm#
www.panna.org/panna/resources/documents/nowhereToHideAppA-D.pdf
http://europa.eu.int/comm/dgs/health_consumer/library/press/press170_en.pdf
http://europa.eu.int/comm/food/fs/sc/scan/out55_en.pdf
http://europa.eu.int/comm/dgs/health_consumer/library/pub/pub08_en.pdf
Official Journal of the European Communities, 9.3.2002, ref (2002/201/EC)

Index | Dairy Products | Egg Products | Honey Products |
Meat Products - Lab | Meat Products - Domestic | Meat Products - Import | Dioxin Annex


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