How to Assess the Risk of Emerging Chemical Contaminants in Foods
There is no question that multistate foodborne illness outbreaks associated with the microbiological contamination of food products captured the majority of food safety-related headlines in 2006 and 2007. The broad range of affected food categories—from fresh spinach and tomatoes, to further processed foods like peanut butter, canned green beans and ready-to-eat meats—and the resulting spate of product recalls is clearly spurring industry and regulators to speed the development and application of risk-based food protection strategies and initiatives.
While microbiological food safety issues are top-of-mind for many food companies, regulators and consumers, the challenge of assessing the risk posed by emerging environmental chemical contaminants in the food supply is steadily gaining ground in the media spotlight. In addition to last year’s highly publicized contamination of pet food and other products by the chemical adulterant melamine, media reports are more frequently covering potential food safety risk data associated with heavy metals, pesticides, veterinary drug residues, naturally occurring environmental toxins and industrial chemicals. Recent newsmakers, such as methylmercury in fish, acrylamide in fried foods, benzene in soft drinks and dioxins in a variety of foods, are just a few of the chemical food safety issues flowing to the front pages on the wave of new studies and toxicological surveys.
Emerging chemical contaminants are associated with numerous wide-ranging and overlapping environmental issues. Food safety stakeholders face a complex matrix of challenges in identifying, characterizing, preventing and managing risks associated with emerging chemicals effectively. For the food industry, these contaminants or potential contaminants affect every aspect of the supply chain, from every single ingredient that is included in a product, used in the manufacture of the product, or used in the manufacture of any ingredient that goes into the product. Nonetheless, as consumers become more vocal in questioning what chemicals or chemical residues are contained in the products they eat, and as regulatory bodies consider changes in rules or standards regarding materials that companies may use in foods or as processing aids in the manufacture of foods, industry’s imperative is to stay proactive in assessing the risk of emerging chemicals.
To some extent, it is impossible to develop a comprehensive list of chemicals that food companies should focus on, given the complexities of environmental, agricultural, food and chemical composition, supply chain and regulatory factors. However, keeping up-to-date on new public health research, occurrence data, regulatory initiatives, and advanced analytical and control methods will enable food companies to make more informed decisions about which contaminants pose a threat to their businesses and how to mitigate and manage those risks successfully.
Defining Emerging Chemical Contaminants
Today, governments and process authorities throughout the world are focusing efforts on determining the toxicological implications of human exposure to both known and newly identified chemical contaminants, developing standards for methods and levels of detection, identifying prevention and management strategies for industry, and establishing appropriate regulatory or legislative mandates as necessary. But what are we really talking about? The U.S. Geological Survey (USGS) defines emerging chemical contaminants as “any synthetic or naturally occurring chemical or any microorganism that is not commonly monitored in the environment but has the potential to enter the environment and cause known or suspected adverse ecological and(or) human health effects.”
In defining an emerging chemical as “unregulated, recently discovered and potentially of concern to human health and the environment,” known chemicals that have posed problems historically can also be included in the discussion of emerging chemicals. These chemicals, such as benzene or pesticides, can reemerge after years of dormancy as issues to industry. Although these aren’t new chemicals, they are problems that have existed historically and that are revisited with a current population.
As alluded to in the USGS definition, emerging chemicals become known as potential issues through a variety of ways. First, with advances in analytical detection, industry is able to analyze more chemicals to much lower concentrations, resulting in a seemingly unending array of identified compounds that, since now known, must be addressed. We know that chemical contaminants that pose a risk range from pesticides, veterinary drugs, mycotoxins, banned food dyes, industrial chemicals (e.g., acrylamide, perchlorate, benzene), radionuclides, environmental and heavy metals (e.g., arsenic, cadmium, lead, mercury, methylmercury) and persistent organic pollutants (e.g., polybrominated diphenyl ethers, dioxins, polycyclic aromatic hydrocarbons). The ability to detect and measure more chemicals at extremely low levels in environmental, food or water matrices not only adds to the shopping list of potential threats but adds to the complexities of deciphering whether a chemical measured at parts-per-billion or trillion (ppb/ppt) levels rather than a parts-per-million (ppm) level has, in reality, more of a health implication for consumers.
Another less objective reason that some chemical contaminants become known as potential issues to the business involves how the public perceives the safety or wholesomeness of a product, whether the issue raised has real health implications or not. If a product contains some level of arsenic, it may not matter to the consumer that it is well below a threshold limit or is scientifically shown to be of little significance because the compound has a back history associated with adverse health effects. The reality is that in many cases the public perception of a product drives how a product is designed or redesigned even more than scientific fact or evidence to the contrary. Food companies will need to factor this “real problem vs. phantom issue” consideration into their risk assessment strategies.
Sources of Emerging Chemicals
Today, more work is being done in the US and the EU involving the chemical analysis of human tissues, blood and breast milk. As researchers find chemical residues in these clinical samples, the question becomes, where are they coming from and what is the toxicological significance? In other words, when a compound is tested in a laboratory and it is found that it has high toxicity, persists or is not readily degradable, how does that translate to health implications outside of the lab environment?
In general, the areas currently receiving the greatest emphasis by the food and other industries include agricultural residues; additives/colorants/flavors; impurities; manufacturing processes; source water; and packaging. Many industries are beginning to look at various chemical threats to their sector’s businesses, including heavy metals in dyes or other kinds of plasticizers or hydrocarbons found in source water or packaging materials. Although these chemicals are used in very small quantities because their applications cross myriad manufacturing sectors, they can be detected via biomonitoring at wastewater treatment plants or through product evaluations.
Impurities are another big issue under the emerging chemicals umbrella. These represent a “grey zone” not only in terms of identifying the source of an emerging issue but whether a specific impurity carries with it attendant health implications. This goes to the heart of knowing the composition of a product because although the manufacturer may know what materials were put into the product (i.e., the black-and-white components), the company is not necessarily looking for what else is in the product, hence the problem of the “grey zone.” Additionally, a food product manufacturer doesn’t necessarily know how much of an impurity is in that grey zone, what category or level of impurity it represents, or even whether it has some desirable attributes.
Since many nongovernmental organizations (NGOs) and regulators overseeing the implementation of California’s Prop 65 requirements are targeting “impurities” right now, many companies are taking a closer look to see how much they actually know about materials used in their products or in the processing of their products. Similarly, we are beginning to see a lot of material safety data sheets (MSDSs) given to further processing customers by ingredient and raw materials suppliers that make Prop 65 compliance statements, such as “This product may contain…” followed by a long, broad list of organics, metals, processing chemicals, and so on—statements which may indemnify suppliers, resulting in a secondary scale-up of issues and questions from the ingredient supplier to the processing facility, which now knows that a laundry list of chemicals may be in the final product as well. In turn, this raises a specter about what levels of such impurities are in the product as well as questions about what the consumer might be exposed to by ingesting the product.
Other emerging chemical issues to be considered in a food company’s risk analysis include those associated with water sources and packaging. Whether the processor is using water as a product ingredient or in the manufacturing process, there is a possibility that the water contains some impurity or treatment chemical that is carried into the product in low concentrations. Potential packaging issues related to inks, plasticizers, dyes and other potential contaminants are not necessarily associated with the product itself but are tangential to it, which in turn raises questions about the integrity of the product.
Contaminant Reports from the USGS and CDC
The most recent USGS and CDC chemical contaminant reports provide an overview of some specific chemicals of interest that food companies should be aware of when doing risk analysis:
• USGS Pharmaceuticals, Hormones, and Other Organic Wastewater Contaminants in US Streams, 2002. This paper, published in the American Chemical Society’s journal, Environmental Science & Technology, focused on analytical methods development, environmental occurrence, source identification, and transport and fate of the following target analytes: Veterinary and human antibiotics (22); prescription drugs (19); steroids and hormones (15); and 39 other wastewater-related compounds (insecticides, plasticizers, fire retardants, etc.), for a total of 95 analytes surveyed.
The USGS detected 82 of the 95 targeted analytes, with as many as 38 analytes detected in a sample. The most frequently detected compounds were steroids, non-prescription drugs, insect repellent, detergent metabolites, disinfectants, dyes and plasticizers. Although the initial focus and expectation of the USGS researchers was to find hormones and antibiotics, surprisingly the biggest incidence of chemicals found fell into the “Other” category where they crossed in the different sectors studied (Figure 1). The attached bar charts show the different classes of chemicals identified, their concentrations on the lower scale and the detection frequency on the upper scale. As shown on the chart, fragrances and flavors were detected at low levels but were placed on the list because these residues were found in many survey sites.
Because the USGS surveyors picked up so many of these “other” chemicals, the agency put chemical suppliers on notice that their chemicals were showing up in the environment. This spurred questions aimed at those industries. For example, dye manufacturers were queried about the composition of their dyes, how they are handled by conventional wastewater treatment, and whether there were implications for long-term low-level releases and associated problems. Food manufacturers who receive supplies from chemical manufacturers are also feeling the pressure to answer similar questions about further processed products.
• CDC National Report on Human Exposure to Environmental Chemicals 2005. The nation’s public health agency reports its biomonitoring results every two years as part of the National Health and Nutritional Examination Survey (NHANE). The number of chemical contaminants with public health implications has risen exponentially since the first report was issued in 2001: