INTERVIEW: Dioxin Contamination - A Recurring but Preventable Problem for the Feed Industry.
The discovery of dioxin in Chinese-manufactured vitamin A palmitate feed grade in March, followed by the detection of the contaminant in Ukrainian organic maize for use in organic poultry feed in April-May are the latest demonstrations that dioxin is a recurring problem in the European animal feed industry.
[Feedinfo News Service] According to you what are the main causes of dioxin-like chemical contamination in animal feed and feed additives?
[George Clark] Dioxin-like chemicals (DLCs) are formed as trace contaminants in burning and incineration processes when aromatic compounds are burned in the presence of chlorine, so they are ubiquitous environmental contaminants.
Polychlorinated biphenyls (PCBs) were manufactured as transformer fluids until the 1970s so there are highly contaminated sites with high levels of DLCs.
These environmental contaminants are bio-concentrated in fat tissues of animals and fish, so the rendering of fats and recycling of DLCs is one of the primary sources of contamination of feed and food. This was the reason for the Belgian food crisis in 1999 when recycled fats were contaminated and why Belgium monitors their feed and food supply for DLCs.
DLCs can contaminate some minerals that are produced in smelting processes (i.e. copper sulphate), which acts as a catalyst for the production of DLCs in incineration.
Binder clays to reduce moisture and retard mold formation have been demonstrated to be occasionally contaminated and should be monitored for use in feed. The contamination incident in 1997 with ball clay in 7 southern states of the United States affected chicken, eggs and catfish production.
Processing procedures can cause DLCs to contaminate certain feed substances. An example of this is the processing of citrus pulp product (CPP) through alkali treatment to digest the feed.
In summary using a Hazard Analysis Critical Control Point (HACCP) monitoring of entry points for DLCs to enter the feed supply suggests that monitoring of fat and oils, mineral supplements, and processing methods would provide assurance that these environmental contaminants are reduced in the feed supply.
[Feedinfo News Service] In March 2010, Feedinfo News Service provided coverage to a European discovery of dioxin in a shipment of Chinese-manufactured vitamin A palmitate feed grade for use in premix. The dioxin was traced back to an intermediate product used in the manufacture of the vitamin A palmitate -- thionyl chloride. What is XDS' overall view of the situation?
[George Clark] It is XDS' view that these contamination incidents are being detected since there are monitoring systems in place. The fact they are being detected demonstrates the utility of the monitoring programme in identifying critical control points to keep these ubiquitous environmental chemicals out of the food supply. The evidence that thionyl chloride may be a source for dioxins suggests that monitoring could be implemented in this process.
[Feedinfo News Service] Dr. Clark, often dioxin is found by using a GC/MS analysis. Can you tell us what GC/MS is? And can you compare that to your own XDS-CALUX detection system? According to you, which system is the fastest and most cost-efficient?
[George Clark] XDS CALUX analysis is carried out by a live cell. The mechanism of how dioxins are toxic involves changing gene expression that ends in the change of the proteins that are synthesized by the cell. DLCs do this by binding to an intracellular receptor (Ah receptor) which goes into the nucleus. In the nucleus it binds DNA causing genes nearby this binding site to be expressed. This results in the synthesis of RNA and then protein. In the cells genetically engineered by XDS, we have placed the gene for the firefly next to the binding site that the receptor binds. In these cells luciferase, the protein of the firefly, produces light as the protein is expressed. We measure the light produced from a sample and compare it to the light produced by a standard of dioxin. In this way, we can calculate a biologically based Toxic Equivalency (TEQ). The receptor and the cell respond to all of the toxic DLCs that are present.
Gas Chromatography/Mass Spectrometry (GC/MS) detection systems are large complex and expensive instruments. These instruments separate chemicals by their solubility in gas and as the chemicals exit the GC they are bombarded with ions and then separated by powerful magnets to measure a specific mass that is characteristic of the DLCs. There are 29 DLCs including 17 chlorinated dioxins/furans and 12 PCBs. These machines identify each compound individually with a "spike" related to its specific chemical structure and mass. To provide an estimate of toxicity the mass of the chemicals is multiplied by a factor scaling the relative toxicity of the DLCs and then added together. Toxic Equivalency Factors (TEFs) were derived by a review of toxicity data for each of the DLCs by an expert committee of the World Health Organization (WHO). The mass of each chemical for each spike is multiplied by the TEF for that chemical, and added all together to give the total toxic equivalency (TEQ) for the sample. The GC/MS instrumental method has been in existence longer and measures each individual chemical and thus has wider regulatory acceptance. CALUX is perfect for screening and monitoring for contamination and if it is found, the confirmation by GC/MS provides the identification of the chemicals that are present that is used for regulatory intervention.
The XDS CALUX/EPA bioassay method 4435 can analyze about 40 samples per hour. GC/MS can analyze approximately one sample per hour per machine. This allows data to be reported more rapidly with the XDS CALUX bioassay. Reporting for GC/MS is generally 30 days versus 2 to 14 days with XDS CALUX. XDS CALUX is about 30-50% of the cost of GC/MS.
[Feedinfo News Service] XDS CALUX bioassay method 4435 not only measures DLCs in feed and food, but it is also validated by the US Environmental Protection Agency to be used for measuring emissions gas, dust, ashes and other cinders, soil sediment and other matrices. XDS also says that it can be used for monitoring and screening dioxin inventories, generation control and remediation. Before we look at some XDS CALUX country studies in food and feed, can you briefly expand on the other uses of the technology?
[George Clark] The XDS CALUX technology can be used to identify sources of dioxins. One of the primary sources is incineration. Air monitoring of incinerators burning waste is one of the primary ways that the technology is used. The residues from incineration may also contain high levels of dioxins. The Hiyoshi Corporation in Japan has licensed our technology and this is the primary use in analyzing sources by which dioxins can enter the environment. What follows are the useful environmental areas for it use.
XDS CALUX has been used to identify DLCs in the following areas: Hazardous waste emissions from incinerators, cement kilns, industrial accidents at chemical manufacturers, sites where chemicals were manufactured, soil remediation and characterization of contaminated sites of industrial activity. XDS currently conducts sediment analysis in areas where runoff may contain industrial waste.
[Feedinfo News Service] In May 2009, XDS announced that its bioassay method 4435 would be used commercially in Chile to screen mineral supplements, other feed additives, and food for export to the European Union with a view to help Chile meet all EU standards for the acceptable levels of dioxins in chicken, pork, beef and fish. In addition, XDS created a partnership with University Adolfo Ibanez. Can you provide us with an update of your Chilean activities?
[George Clark] Given XDS' financial position, it was decided to firstly invest in a commercial partnership with Diagnotec, a Chilean company specialised in the development and commercialisation of biotechnological services. We then later sought ways to invest in our relationship with University Adolfo Ibanez. XDS proposed a dioxins inventory in Chile, similar to the one in Japan, in partnership with the University, but this was never funded.
XDS mainly works with the Servicio Agricola y Ganadero (SAG), the Chilean Agricultural and Livestock Service. This agency regulates the safety of the food chain. We also work with the Instituto de Salud Publico (ISP) that regulates drugs, cosmetics, and food used medicinally. Both these agencies are in process of validating our technology in Chile.
SAG works in conjunction with the Chilean Pork Producers' Association called Asprocer. Asprocer has provided feed and food samples for analysis. These results, along with validation studies, will be analysed by SAG and ISP for purposes of validation of our methods.
There have been two contamination incidents in Chile, both traced back to the minerals supplements used in feed. One, in 2008, resulted in pork contamination detected by the Koreans. The other contaminated mineral was caught by screening and did not enter the food chain.
[Feedinfo News Service] Chile's pork export industry was negatively impacted by the matter. Due to bans from Japan and South Korea, Chilean pork exports fell by around 15% that year. The mineral supplement containing dioxin was identified as zinc oxide. Chile requested your help shortly after the scare, but, nonetheless, after the event. In which markets is XDS-CALUX currently available? Has XDS been contacted by countries without reported dioxin contamination cases wishing to prevent these situations from ever happening? If a country wishes to use XDS-Calux, how long does it take before it can autonomously use the detection system?
[George Clark] We are promoting our technology to countries that adopt the EU standards for sampling and screen analysis, such as Chile. China is adopting the EU standards as well. Israel is planning to develop standards based on its research. Brazil and Saudi Arabia are doing the same.
XDS is pursuing agreements in these countries and multiple opportunities in China and Asia. We promote our rapid screening technology to help them adopt the standards for import necessary to protect the food chain from dioxins inexpensively.
Unfortunately, it seems an incident has to happen before there is any real concern over prevention. However, I would say that Israel and Saudi Arabia seem to fall into the prophylactic category and we are helping them as much as we can prior to any incident.
Monitoring can be instituted immediately by sending samples to our laboratory in Durham, NC (USA). To train personnel and install a laboratory can be accomplished in a couple of months however to obtain ISO certifications within a country can extend this process to about a year for the installation of a laboratory and validation studies to be completed. It can be done more quickly, but it takes an investment of hard work to insure reliable, accurate and reproducible results.
[Feedinfo News Service] In recent years, EU imports of Chinese feed additives have been found to contain dioxin on several occasions: vitamin A palmitate (2010), feed-grade glycine (2007), copper sulphate (2006 and 2007) and choline chloride (2006). According to you why are Chinese feed additives still concerned by dioxin contaminations? What action is being carried out in China to stop this? Has XDS developed any partnership in the country?
[George Clark] I cannot speak for the Chinese government, or the US government. However, in China, it seems that the testing is more or less voluntary, as is the case with the US. China is in the process of adopting guidelines for dioxins contamination that are in line with the EU guidelines for import.
Information from a trusted source indicates the policy seems to be that in China the person selling the product should test because it is wise, not because it is required. Our source indicates the Chinese government has no incentive to implement restrictive regulation because the policy could negatively impact their export business.
XDS is in the process of developing a relationship with a Chinese distributor for its analyses and technology in China. We have to rely on the distributor to understand the Chinese market.
[Feedinfo News Service] A question relating to dioxin limits in animal feed. Why are they not the same all over the world? Shouldn't there be a harmonised system in place? Are the European Union dioxin limits for feedstuffs (0.75ng/kg), feed material of plant origin (0.75 ng/kg), feed materials of mineral origin (1.0 ng/kg) and for animal fat (2.0 ng/kg) strict?
[George Clark] Perhaps a harmonised system should be in place, but that will be an arduous and time-consuming process fueled by the uncertainty regarding the medical risks of dioxins/PCBs exposure in humans, and exiting levels of contaminants. Part of the process will be motivated by politics, economics and public health concerns. It appears that the EU is driving world regulatory limits since they were the first to establish limits based on contaminant levels and risk assessment of hazards.
For example, the limits on fish in Europe are set at 6 ppt because an inventory was done to set tolerances that were achievable given the current levels of contamination that exist. This is why there are different limits for different feed components.
There exists a need to comply in countries like Chile to adopt these limits so they can export to the EU, but also to adopt the limits internally to ensure the safety of the food chain for the citizens of Chile.
[Feedinfo News Service] Finally Dr. Clark, according to you, is the global feed industry doing enough in terms of dioxin detection?
[George Clark] Everywhere we have been in the world there is a lot of interest in the safety of the food chain from the farm to the fork. As you know, dioxins and dioxin like molecules are a small part of the necessary monitoring. Almost without exception, anyone who handles feed, feed additives or food from any country is aware of the issue with dioxin contamination due to the many incidents that have occurred. The US is doing voluntary monitoring by companies that are conscientious and concerned about food safety in adhering to good practices for the feed industry.
Our challenge is to bring them awareness that this screening is not as arduous or expensive as they may think.
We also face the challenge to create the awareness that dioxins contamination can occur at any time, therefore, continuous scheduled testing should be necessary as part of Hazards Analysis and Critical Control Point (HACCP) plans.
We find our company's challenge to be one of making the right amount of noise to the right people and to educate the industry on these issues.
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|Publication:||Feedinfo News Service|
|Date:||Jun 2, 2010|
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