RG-8 Regulatory Guidance:
Contaminants in Feed (formerly RG-1, Chapter 7)
Section 2: Action Levels for Dioxins, Furans, Dioxin-like polychlorinated biphenyls (PCBs) and Total PCBs in Livestock Feed
- Fact Sheet - CFIA Advises Not to Use Chemically-Treated Wood Near Livestock Feed and Animals
- Appendix
The CFIA regularly monitors livestock feed for environmental contaminants which have the potential to impact the safety of the food chain and the health of animals. Beginning in 1998, different types of livestock feeds and feed ingredients were surveyed to determine the levels of dioxins, furans, and PCBs. It has been estimated that food is the major source of human exposure to dioxins, furans, and PCBs, with 90 per cent being contributed by foods of animal origin (Fürst, Beck, and Theelen, 1992). Estimates also indicate that 80 per cent of these contaminants found in animal products originate from livestock feeds. Based on initial survey results and a review of the scientific literature, fish meals, fish oils, fish feeds, and mineral ingredients were considered to be potential sources of these contaminants and, as such, have been targeted for regular monitoring as part of the "Dioxin, Furan, and PCB Monitoring Program". The sampling results have been compiled to assess the background levels of dioxins, furans, and PCBs.
Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), which are often referred to simply as "dioxins", are formed during the manufacture of chlorinated hydrocarbons, and so may be present as contaminants in PCBs, organochlorine pesticides, and phenoxyacid herbicides. Bleaching processes using elemental chlorine can also lead to the formation of dioxins. In addition, they are produced when organic matter is burned in the presence of chlorine, and are therefore found in fly ash from incinerators and produced naturally in forest fires. PCDDs and PCDFs are highly persistent in the environment, and are considered ubiquitous environmental contaminants. They can be found at very low levels in all living organisms and are able to bioaccumulate in food chains due to their lipophilic characteristics.
Depending on the degree of chlorination (1 - 8 chlorine atoms) and the substitution pattern, one can distinguish between 75 PCDDs and 135 PCDFs, called "congeners". The toxicity of dioxin congeners varies considerably. Of the 210 congeners, only 17 are of toxicological concern, and the analysis for "Total Dioxins" conducted by the CFIA is based on the combined concentration of these 17 dioxin and furan congeners. Exposure levels or residues are expressed in toxic equivalents (TEQ) of the most toxic congener, 2,3,7,8-tetrachloro-dibenzo-p-dioxin (2,3,7,8-TCDD), which allows the comparison of analytical results.
The International Agency for Research on Cancer (IARC) has classified 2,3,7,8-TCDD as a Group 1 carcinogen, which indicates that it is carcinogenic to humans. Effects seen in experimental animals include endometriosis, developmental effects at the behavioural level, reproductive effects, and toxicity to the immune system. The biochemical and toxicological effects following dioxin exposure are dependent on the tissue level, not the dose, and are therefore the same regardless of whether the intake is a large dose over a short period or a small dose over a long period.
PCBs are also considered to be persistent pollutants. PCBs differ from PCDDs and PCDFs in that they were intentionally manufactured for use in transformers, insulators, capacitors, etc., while dioxins and furans are produced unintentionally as unwanted by-products. PCBs consist of 209 different congeners and the analysis for "Total PCBs" conducted by the CFIA is based on the combined concentration of 72 of the 209 individual PCB congeners. Some of the 209 congeners, because of their chemical structure and biological activity, are considered to be "dioxin-like".
Twelve to 14 of the most toxic dioxin-like PCBs can also be expressed in toxic equivalents (TEQ). In 1977, the manufacture and import of PCBs was banned in North America, and the PCBs still used in electrical applications are currently being phased out.
Note: From this point in the section, the term "dioxins" will refer to dioxins (PCDDs), furans (PCDFs) and dioxin-like PCBs. The CFIA calculates total dioxins, including dioxin-like PCBs, using the international standardized reporting method of WHO-TEQ (World Health Organization - Toxic Equivalency) with the appropriate 1998 WHO Toxic Equivalency Factors (Van den Berg et al., 1998). This method includes seven dioxin congeners, 10 furan congeners and 12 dioxin-like PCBs. All of the data and action levels (except for total PCBs) in the remainder of this section are expressed using the WHO-TEQ terminology.
Acceptable analytical methods generally include a clean-up/extraction system (liquid-liquid extraction or Soxhlet extraction) and the use of gas chromatography with high resolution mass spectometry. This is the method used by the CFIA laboratory for the analysis of samples. The XDS-CALUX® EPA method #4435 has been reviewed and is an acceptable screening method for minerals. If other methods of analysis are used, the methods must first be reviewed by the CFIA laboratory to determine if the results are acceptable.
Based on the data obtained from sampling as part of the Monitoring Program, action levels have been set for total dioxins in: fish meals; fish oils; fish feeds; and minerals, mineral complexes, macropremixes, and anti-caking agents (see Table 3). Also, based on sampling results, the CFIA has reassessed its Action Level for Total PCBs in marine oils3 used as a livestock feed ingredient (see Table 4). For a further explanation of how these action levels were derived, please consult the Appendix.
These action levels are considered interim levels. In the future, these action levels may be lowered, in an effort to continually reduce unnecessary sources of contaminants in foods of animal origin. This approach is consistent with the CFIA's policy of identifying and eliminating sources of contaminants in the food chain.
Feed manufacturers are reminded of their responsibility to produce feeds which are safe for all classes of livestock and to prevent the introduction of contaminants into the food chain via food of animal origin.
| Livestock Feed Ingredient | Action Level (ng WHO-TEQ/kg) |
|---|---|
| Fish Meal | 3 |
| Fish Oil | 16 |
| Fish Feed | 6 |
| Minerals, Mineral Complexes, Macropremixes, and Anti-caking Agents |
1.5 |
Table 4. Action Level for Total PCBs (mg/kg) for marine oils.
| Livestock Feed Ingredient | Action Level (mg/kg) |
|---|---|
| Marine Oils | 0.3 |
References
Fürst, P, Beck, H., and Theelen, R.M.C. Assessment of human intake of PCDDs and PCDFs from different environmental sources. Toxic Substances Journal, 12:133-150, 1992.
Van den Berg et al., Review: Toxic Equivalency Factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife. Environmental Health Perspectives, 106:775-792, 1998.
3. For the purposes of this section, marine oils are defined as oils from approved marine sources (e.g. fish oil, mollusc oil), listed in Schedules IV and V of the Feeds Regulations.
Fact Sheet - CFIA Advises Not to Use Chemically-Treated Wood Near Livestock Feed and Animals
The Canadian Food Inspection Agency (CFIA) is advising livestock producers across Canada not to use chemically-treated wood structures near livestock feed or food-producing animals because they can transfer potentially harmful levels of chemicals into animal products, such as meat, milk and eggs.
As part of the CFIA's residue monitoring program, dioxin levels higher than background were detected in raw milk from two British Columbia dairy operations. The dioxin was found at levels that are not considered an immediate health risk by Health Canada. The levels found did, however, trigger follow-up action to identify and eliminate the source of contamination, in line with Canada's approach to managing dioxin in the food supply. Dioxins are released into the environment through natural and industrial processes and are commonly found in low levels throughout the food chain around the world.
The investigation indicated that chemically-treated wood used in some silage bunkers (animal feed containers) may, in large part, be the source of the dioxin detected. Exposure to wood treated with chemicals, such as pentachlorophenol (PCP), has been shown to result in higher than background levels of dioxins in livestock feed, which can then transfer into animal products. Further follow-up after precautionary measures were implemented indicated lowered levels of dioxin.
Producers should ensure that livestock feed is not stored where it can come into direct contact with chemically-treated wood structures. Animals should also not be allowed to come into contact with chemically-treated wood, including sawdust or shavings that could be used for bedding. At a minimum, bunker silos containing this wood should be lined with a plastic tarp and untreated lumber. Gloves should be worn when handling any treated wood and scraps must be disposed of in accordance with provincial/territorial and municipal regulations.
Appendix
Action Level for Dioxins in Fish Meal
Samples of fish meal were taken by the CFIA from 2002 to 2006 and analysed for dioxins. The Action Level for Dioxins in Fish Meal was then calculated by adding one standard deviation to the mean dioxin level in these samples (see Figure 1) and rounding to the nearest ng WHO-TEQ/kg (nanogram World Health Organization - Toxic Equivalents per kilogram). Based on this calculation, the Action Level for Total Dioxins in Fish Meal has been set at 3 ng WHO-TEQ/kg. The majority of fish meal sampled from 2002 to 2006 still falls below this new action level, which will only affect fish meal sources which have unnecessarily high levels of total dioxins, furans, and dioxin-like PCBs.
Figure 1. Total Dioxin Levels in Fish Meal Samples Destined for Livestock Feed from 2002 to 2006
Click on Image for Larger View
Description of chart - Total Dioxin Levels in Fish Meal Samples Destined for Livestock Feed from 2002 to 2006
Action Level for Dioxins in Fish Oil
Fish oil samples were taken by the CFIA from 2002 to 2006 and analysed for dioxins. The Action Level for Dioxins in Fish Oil (see Figure 2) was then calculated by adding one standard deviation to the mean dioxin level for these samples and rounding to the nearest ng WHO-TEQ/kg (nanogram World Health Organization - Toxic Equivalents per kilogram). Based on this calculation, the Action Level for Dioxins for Fish Oil has been set at 16 ng WHO-TEQ/kg. As seen in Figure 2 below, most of the fish oils sampled from 2002 to 2006 as part of the monitoring program are below this new Action Level, and therefore only fish oil sources which have unnecessarily high levels of total dioxins, furans, and dioxin-like PCBs should be affected.
Figure 2. Total Dioxin Levels in Fish Oil Samples Destined for Livestock Feed from 2002 to 2006
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Description of chart - Total Dioxin Levels in Fish Oil Samples Destined for Livestock Feed from 2002 to 2006.
Action Level for Dioxins in Fish Feed
The Action Level for Dioxins for Fish Feeds has been set at 6 ng WHO-TEQ/kg (nanogram World Health Organization - Toxic Equivalents per kilogram). The basis for setting this action level was the calculation of the dioxin level resulting from a maximum inclusion of fish oil of 30 per cent and a maximum inclusion of fish meal of 40 per cent. Given the worst case scenario, this would mean 4.8 ng WHO-TEQ/kg dioxins from fish oil and 1.2 ng WHO-TEQ/kg from fish meal, for a total of 6 ng WHO-TEQ/kg. Sampling of fish feeds as part of the Monitoring Program has been more limited than sampling of fish feed ingredients, however all of the fish feeds sampled from 2002 to 2006 had levels that were well below the Action Level.
Action Level for Dioxins in Minerals, Mineral Complexes, Macropremixes, and Anti-caking Agents
Samples of minerals, mineral complexes, macropremixes, and anti-caking agents were taken by the CFIA from 2002 to 2007 and analysed for dioxins. The Action Level for Dioxins in Minerals, Mineral complexes, Macropremixes, and Anti-caking Agents was calculated by adding one standard deviation to the mean dioxin level for these samples and rounding up to the nearest 0.5 ng WHO-TEQ/kg (see Figure 3). Based on this calculation, the action level for Dioxins in mineral products has been set at 1.5 ng WHO-TEQ/kg (nanogram World Health Organization - Toxic Equivalents per kilogram). For the calculation of this action level, five extreme outlier samples (greater than 15 ng WHO-TEQ/kg level) were removed from consideration, since these had been directly linked to contaminated products and would not be considered to be representative of the normal levels found in minerals in the feed industry. Most of the samples from the Monitoring Program from 2002 to 2007 fell below this action level.
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Description of chart - Total Dioxin Levels in Various Minerals and Minerals Supplements Destined for Livestock Feed from 2002 to 2007
Action Level for Total PCBs in Marine Oils
The Action Level for PCBs in Marine Oils has been reduced to 0.3 mg/kg or 300 µg/kg. The new level for total PCBs was calculated by adding one standard deviation to the mean total PCB level for fish oil samples taken by the CFIA from 2000 to 2006, and rounding to the nearest 0.1 mg/kg (see Figure 4). The majority of the fish oil samples still fall below this new action level, which only affects samples which have unnecessarily high levels of total PCBs. Marine oils should contain less than 0.3 mg/kg total PCBs in order to be used in the manufacture of livestock feeds.
Click on Image for Larger View
Description of chart - Levels of Total PCBs in Fish Oil Samples Destined for Livestock Feed from 2002 to 2006 Samples
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