Consumer Reports (CR) has called on USDA to remove certain Lunchables food kits from the National School Lunch Program due to high levels of sodium and heavy metals found in the products.

USDA currently allows two Lunchables kits—Turkey & Cheddar Cracker Stackers and Extra Cheesy Pizza—to be served to nearly 30 million children through the National School Lunch Program. To meet the program’s requirements, Kraft Heinz added more whole grains to the crackers and more protein to the Lunchable kits designed for schools, compared to store-bought versions.

CR recently compared the nutritional profiles of two Lunchable kits served in schools and found they have even higher levels of sodium than the kits consumers can buy in the store. CR also tested 12 store-bought versions of Lunchables and similar kits and found several contained relatively high levels of lead and cadmium. All but one also tested positive for phthalates, chemicals found in plastic that have been linked to reproductive problems, diabetes, and certain cancers.

CR tested store-bought Lunchables and similar kits from Armour LunchMakers, Good & Gather, Greenfield Natural Meat Co., and Oscar Mayer and found lead, cadmium, or both in all. Lead and cadmium can cause developmental problems in children over time, even in small amounts. While none of the kits exceeded any federal limit, five of the 12 tested products would expose someone to 50 percent or more of California’s maximum allowable level for lead or cadmium – currently the most protective standard.

The sodium levels in the store-bought lunch and snack kits CR tested ranged from 460 to 740 milligrams per serving, which is nearly a quarter to half of a child’s daily recommended limit for sodium. CR found that the sodium levels of the Lunchables made for schools, which had a larger portion of meat, are higher than in the store-bought versions. The school version of the Turkey and Cheddar Lunchable for schools contained 930 mg of sodium compared to 740 mg in the store-bought version. Similarly, the Lunchable pizza kit for schools had 700 mg of sodium compared to 510 mg in the store version.

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An October 2023 report released by Consumer Reports found high levels of cadmium and lead in select dark chocolate products, included those from Hershey’s, Trader Joe’s, and other popular brands. The group’s scientists tested 28 dark chocolate bars for heavy metals, and detected cadmium and lead in all of them.

The findings revealed that eating just one ounce from any of the 23 bars tested would put an adult over the limit for both heavy metals that public health experts deem acceptable.

Considering that cadmium and lead are linked to a host of health problems in both children and adults, the study results are worrisome to many. “The metals can cause developmental problems, affect brain development, and lead to lower IQ,” says Tunde Akinleye, a food safety researcher with Consumer Reports who led the study. “Frequent exposure to lead in adults, for example, can lead to nervous system problems, hypertension, immune system suppression, kidney damage, and reproductive issues.”

Earlier this year, the National Confectioners Association released results of a three-year study of the sources of lead and cadmium in cocoa and chocolate and how levels may be reduced in the future, though they believe the current levels aren’t dangerous. “Chocolate and cocoa are safe to eat and can be enjoyed as treats as they have been for centuries,” Christopher Gindlesperger, senior vice president of public affairs and communications at NCA, tells Food Quality & Safety. “Food safety and product quality remain our highest priorities and we remain dedicated to being transparent and socially responsible.”

Consumer Reports identified and prioritized a list of recommended cadmium and lead reduction measures for the industry to consider implementing, including sourcing cocoa beans from areas with lower levels of the metals.

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A study conducted by researchers at the University of Buffalo in New York and recently published in the journal Current Problems in Pediatric and Adolescent Health Care looked at gaps in the U.S. regulation of toxic metals in baby foods such as rice cereal, formula, purees, and puffs.

The researchers determined that the U.S. doesn’t have the kind of strict regulations for commercially produced baby foods that parents might expect. “It is concerning that there are gaps in food contaminant federal guidelines, particularly for baby foods. Parents might expect and trust that their infant’s commercially produced baby food is automatically protected by tightly regulated guidelines, but that is just not the case,” says the study’s lead author, Sarah J. Ventre, MD, clinical assistant professor in the department of pediatrics in the Jacobs School of Medicine and Biomedical Sciences at the university.

Gauri Desai, PhD, MPH, a clinical assistant professor in the department of epidemiology and environmental health at the university and who was part of the study’s research team, notes that there are few clear, evidence-based guidelines on the maximum tolerable limits of toxic metals in foods and little understanding of toxicant exposure or adverse health effects attributable to dietary exposure in the current regulatory guidelines. “Several foods consistently appear in the literature as potential sources of toxic element exposure,” she says. “Both homemade as well as store-bought foods are found to contain toxicants. Contaminated drinking and cooking water, including water used to prepare infant formula, could also be a major exposure source.”

The researchers found that, while there is an increase in the number of studies focused on the presence of contaminants in foods consumed by children, there is still a dearth of information on the topic. The researchers were also struck by the scarcity of clear guidance that takes into account the complexity of issues—that multiple toxic element exposures may be occurring, and that these stem from the same diets that provide health-promoting nutrients. “First, we do not have a comprehensive picture on the extent of exposure to toxic elements in young children,” Katarzyna Kordas, PhD, associate professor of epidemiology and environmental health at the university’s School of Public Health and Health Professions and senior author of the study, tells Food Quality & Safety. “Second, we do not know how exposure to toxic elements through the diet is affecting child health. We know that toxic elements are bad for children’s development and health, but healthy foods in themselves are good because they provide beneficial vitamins, minerals, bioactive components, etc. Will that counterbalance the effects of toxic elements? While that is the hope, there are no studies to allow us to say this for sure.”

She adds that clearer recommendations are needed for parents, but this is not an issue they can be expected to address alone. There is a need for broader, systemic protections supported by well-developed research studies to address the knowledge gaps. “More frequent inspection of manufactured foods [and] better labeling, combined with public messaging on what the labels mean, should be part of the strategy to limit exposures in young children.”

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On January 24, FDA unveiled a draft guidance for manufacturers to reduce lead levels in processed foods intended for children younger than 2 years of age. The move was made as part of FDA’s Closer to Zero program, which was created to help reduce young children’s exposure to lead, arsenic, cadmium, and mercury to the lowest levels possible.

“For more than 30 years, the FDA has been working to reduce exposure to lead, and other environmental contaminants, from foods,” Robert M. Califf, FDA’s Commissioner, said in statement. “For babies and young children who eat the foods covered in today’s draft guidance, the FDA estimates that these action levels could result in as much as a 24% to 27% reduction in exposure to lead from these foods.”

Known as Action Levels for Lead in Food Intended for Babies and Young Children, the draft guidance calls for manufacturers to set new action levels of 10 parts per billion (ppb) for fruits, vegetables (excluding single-ingredient root vegetables), mixtures (including grain and meat-based mixtures), yogurts, custards/puddings, and single-ingredient meats; 20 ppb for root vegetables; and 20 ppb for dry cereals.

Although not binding under law, FDA could take these action levels into account when considering whether to bring enforcement action in a particular case.

Vineet Dubey, an environmental attorney based in Los Angeles, has been fighting to reduce lead levels in baby food for several years, pushing for the federal government to set levels for heavy metals in baby food, whether it be through the Closer To Zero effort or the Baby Food Safety Act. He does not believe the new draft guidance will affect much change, as the levels set forth by the proposal are not a mandate and there are no strict penalties for noncompliance. “The FDA’s own words point out that these proposed lead limits are not ‘legally enforceable responsibilities.’ In other words, consumers should continue to trust baby food makers to do the right thing, which is how we got here in the first place,” he says. “The FDA and Congress need to stop paying lip service about limiting baby and toddler exposure to excessive amounts of lead that’s in the processed food most American parents feed their kids.”

It should be noted that the timeline for FDA to release a draft guidance document is far less than the typical rule-making procedures requiring a notice and comment period, allowing FDA to alert industry more quickly for significant concerns.

Dubey also argues that a maximum allowable lead limit, per serving, needs to be mandated and must come with strict penalties for exceeding set levels. Further, he says that FDA needs to be funded in a way that allows for regular testing and monitoring of baby foods, especially those known to often carry lead, such as sweet potatoes, yams, spinach, and rice. “This guidance is long overdue in even starting to address the problem of lead found in baby food, so hopefully awareness will increase among parents and, possibly, cause some companies to start taking more seriously the danger of lead found in their products,” Dubey adds.

FDA is holding a webinar on this draft guidance for members of industry and the public on March 2. Visit the registration page for more information.

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While a number of studies have shown a connection between dark chocolate and heavy metals cadmium and lead, a new report by Consumer Reports has shed more light on the issue. In its research, the organization measured levels of heavy metals in 28 different dark chocolate products and detected cadmium and lead in all of them. The tested products included chocolate from Hershey’s, Theo, Trader Joe’s and other popular brands.

Too many as these two heavy metals have been linked to several health problems for both children and adults and the FDA notes that lead is toxic to humans and can affect people of any age or health status—though it is most problematic to children and pregnant women. By law, food manufacturers have a responsibility to implement controls to significantly minimize or prevent exposure to chemical hazards, lead included.

In January, Mars Inc. was hit with a proposed class action in New York federal court accusing the confectionery giant of failing to disclose lead and cadmium in several of its dark chocolate bars. A similar claim was made against The Hershey Co., which is facing a suit of its own.

In the latter case, the class action was brought by Christopher Lazazzaro, who cited the Consumer Reports study in the court documents, which tested a trio of Hershey’s dark chocolate bars—Hershey’s Special Dark Mildly Sweet Chocolate, Lily’s Extra Dark Chocolate 70% Cocoa, and Lily’s Extreme Dark Chocolate 85% Cocoa—and found them all to contain the heavy metals. The lawsuit is seeking $5 million from Hershey’s, claiming the chocolate giant’s advertising and marketing campaign for the dark chocolate bars were “false, deceptive, and misleading” since the labels said nothing about containing lead and cadmium.

A week after the suit against Hershey’s was filed, a similar one against Trader Joe’s came about, with the plaintiff saying that the company failed to disclose that the Trader Joe’s Dark Chocolate 72% Cacao and Trader Joe’s The Dark Chocolate Lover’s Chocolate 85% Cacao both contain lead and cadmium.

Still, the National Confectioners Association (NCA), which represents most of the major chocolate companies, claims that the levels found are not dangerous. In 2019, NCA partnered with As You Sow, an organization that pushes for corporate accountability, on a three-year study on the main sources of lead and cadmium in chocolate products and what can be done to lower the amounts. This came about after a 2018 settlement between As You Sow and 32 members of the confectionery industry. “Cadmium and lead are present in cocoa and chocolate due to the soil,” says Christopher Gindlesperger, a spokesperson for NCA. “The products cited in this study are in compliance with strict quality and safety requirements, and the levels provided to us by Consumer Reports testing are well under the limits established by our settlement [with As You Sow].”

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FDA is working to decrease exposure to toxic elements for babies and young children to as low as possible. The new action plan, entitled Closer to Zero, will aim to reduce the toxic elements in foods commonly eaten by babies and young children. The plan follows a February 2021 Congressional report calling on federal regulators to set stricter standards on baby food manufacturers after an investigation into these foods found toxic heavy metals, including arsenic, present.

FDA’s action plan will follow an approach that includes research, regulatory, and outreach efforts. It will start by evaluating existing data from routine testing of the food supply, exposure, risk assessments, and other relevant scientific information. The agency will also consult with stakeholders and experts and will take what it discovers to make any needed adjustments and finalize action levels.

It’s difficult to determine which foods are tainted with heavy metals. “Reducing levels of toxic elements in foods is complicated and multifaceted,” said Janet Woodcock, FDA’s acting commissioner, in a statement. “It is crucial to ensure that measures taken to limit toxic elements in foods do not have unintended consequences—like eliminating from the marketplace foods that have significant nutritional benefits or reducing the presence of one toxic element while increasing another.”

Some believe that, since the plan is designed to produce recommendations and not final standards, FDA has set the bar too low. “Generally, it’s a good sign that FDA has developed a timeline to help guide their work, since it creates some accountability,” Laurie Beyranevand, director for the center for agriculture and food systems at Vermont Law School in South Royalton, tells Food Quality & Safety. “However, FDA is proposing setting action levels for these substances rather than enforceable tolerance levels. From a legal perspective, this may not go far enough ,since action levels are nonbinding—meaning they cannot be used as the basis for an enforcement action, whereas a tolerance level set by regulation can.”

Given the magnitude of this issue and the significant public health challenges this presents to a vulnerable population, she believes interim action levels may be appropriate as the agency develops tolerance levels through regulation, but the public may feel more comfortable with a stronger level of agency oversight.

“From a legal perspective, action levels present an additional challenge in the sense they may not be considered final agency action given their nonbinding nature,” Beyranevand says. “Consequently, if advocates seek to challenge the action levels ultimately set by FDA, they may run into obstacles in court preventing them from doing so.”

FDA says that its data shows that children are not at an immediate health risk from exposure to toxic elements at the levels found in foods today, so, while there is a desire to decrease the amount, it believes its short- and long-term goals for achieving continued improvements in reducing levels of toxic elements in these foods over time is justified.

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In response to a February 2021 report released by the U.S. House of Representatives Committee on Oversight and Reform Subcommittee on Economic and Consumer Policy, FDA has issued a letter to baby and toddler food manufacturers reminding them of their obligations under the FSMA Preventive Controls for Human Food Rule to consider chemical hazards in foods when engaged in their required hazard analysis of food products.

FDA says it will also seek “impactful solutions for reducing toxic elements in foods commonly consumed by babies and young children.” The agency also committed to engaging in a process to set standards and limits for the presence of heavy metals in baby foods.

The new actions include issuing guidance to manufacturers for “key foods,” planning to finalize its action level for inorganic arsenic in infant rice cereal, which it started working on in 2016; and working to finalize its draft guidance for an inorganic arsenic action level in apple juice and release a draft guidance for lead action levels in juices.

“The U.S. Food and Drug Administration takes exposure to toxic elements, such as arsenic, mercury, cadmium and lead, in the food supply extremely seriously, especially when it comes to protecting the health and safety of the youngest and most vulnerable in the population,” said Janet Woodcock, FDA’s acting commissioner of food and drugs, in its statement.

Laurie Beyranevand, director of the Center for Agriculture and Food Systems at Vermont Law School, notes that while this is an important first step and signals a stronger commitment to address the issue of heavy metals in baby foods than we’ve seen from FDA over the past few years, these actions are not enough.

“A few years ago, FDA convened a Toxic Elements Working Group to reduce exposure to toxic elements across FDA’s regulated product categories,” she tells Food Quality & Safety. “The working group prioritized lead, arsenic, cadmium, and mercury, as these metals present the highest public health risk when individuals are exposed at high levels. However, to date, FDA has only issued voluntary guidance to address inorganic arsenic in rice cereal, meaning it contains nonbinding recommendations that can’t be enforced by the agency in the same way a binding regulation can.”

Janilyn Hutchings with StateFoodSafety, a food safety education organization, says that, in addition to taking the new actions it just announced, FDA could also work on drafting action levels for inorganic arsenic and lead in other baby foods. “It could also consider appropriate action levels for cadmium and mercury,” she says. “As more testing and studies are available and more widely used, the FDA will likely implement more changes to ensure the safety of babies and children.”

In Beyranevand’s opinion, FDA should be developing binding standards with set limits that address the amount of heavy metals that can safely be present in infant, baby, and toddler foods, rather than developing nonbinding guidance. “This will require manufacturers to ensure their products are within those limits and enable FDA to enforce the limits against companies that fail to comply,” she says. “Given the vulnerability of this population and the fact that heavy metals are present in many of their first foods, this issue is of paramount importance for public health and safety.”

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A new study by Consumer Reports states that some fruit juices pose potentially harmful levels of heavy metals. In its analysis of 45 fruit juices sold nationwide, the nonprofit advocacy organization found that nearly half contained elevated levels of inorganic arsenic, lead, or cadmium.

According to Hannah Gardener, ScD, nutritional epidemiologist and founder of A Green Slate Consulting, Boston, Mass., foods and beverages can become tainted with heavy metals if they’re grown in contaminated soil and water. Due to past use of heavy metal-containing pesticides, many orchards and fields have become contaminated.

But many heavy metals naturally occur in the environment as well, says Alex Berezow, PhD, vice president of scientific affairs, American Council on Science and Health, New York, New York.

Children, who are particularly vulnerable to the harmful effects of heavy metals, consume a lot of fruit juice. More than 80 percent of parents of children three and under give their kids juice at least sometimes, according to Consumer Reports’ survey.

Gardener says consuming foods with elevated levels of lead, cadmium, and inorganic arsenic can have significant health effects, particularly for babies and children who are sensitive to their effects. “As a potent neurotoxin, lead is toxic to the brain, and especially developing brains,” she says. “Its effects are permanent and irreversible, and there is no safe level of lead consumption. It’s also considered a potent reproductive toxin. Cadmium is also a neurotoxin and reproductive toxin and has damaging effects on the liver. Inorganic arsenic is particularly concerning as it’s known to cause cancer.”

The Consumer Reports’ article encourages the FDA to limit levels of heavy metals in foods. “If the FDA established stricter health-protective limits for heavy metals in foods and beverages, it could mean that manufacturers would have to test their products more thoroughly and identify better growing practices, conditions, locations, orchards, and fields in an effort to limit heavy metal contamination,” Gardener says. “These efforts have grown in some areas, particularly in relation to rice and rice-based foods, for example, where the concern about inorganic arsenic contamination has increased over the past eight years or so.”

But Carl Winter, PhD, extension food toxicologist and vice chair, Department of Food Science and Technology, University of California, Davis, Calif., says it’s difficult to designate a “safe” level for heavy metals in specific foods and beverages because consumers are exposed to heavy metals in a wide variety of foods. In general, research indicates that exposure levels are typically below levels of health significance.

Dr. Berezow points out that regulation usually imposes extra costs, which are invariably passed on to consumers. “Therefore, the government should only impose new regulatory burdens if there is sufficient scientific reason to do so,” he says.

Regarding what steps the food and beverage industry can take to decrease levels of inorganic arsenic, lead, and cadmium in foods and beverages, Dr. Winter says there’s little that can be done at the post-harvest level to reduce metals in foods and beverages. “The primary way to reduce levels of heavy metals is to avoid using foods grown in environments possessing high levels of naturally occurring metals,” he says.

Along these lines, Dr. Berezow says that the best strategy is prevention, which means making sure that industry responsibly uses and disposes of materials that contain heavy metals. “If a site is unduly contaminated, it should be cleaned up,” he says.

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European Union (EU) researchers conducting an experiment in which 57 laboratories from 29 countries volunteered to test for the presence of heavy metals in seafood found that most of the labs came up with similar results, thus underscoring the efficacy of the tests.

The results should enhance consumer confidence, as maximum levels of lead, cadmium, and total mercury in seafood are regulated by EU law, and it has been proven that most participants are able to correctly measure them. In addition, this comparison has highlighted other issues, such as the apparent dependency of the measurements of inorganic arsenic on the type of food tested.

Each laboratory received a sample without knowing the levels of heavy metals present, and was asked to measure and report the values back to the European Commissions Joint Research Centre (JRC).

Excessive intake of heavy metals may lead to a decline in mental, cognitive, and physical health. A particular concern is potential developmental defects in children exposed in utero. From a toxicological point of view, the chemical form in which the metal is ingested plays a significant role. For example, methylmercury is much more toxic than inorganic mercury compounds, while inorganic arsenic is more toxic than the organic species of arsenic, according to a news release from the JRC.

Labs Compare Results

The interlaboratory comparison was organized in support of the European Co-operation for Accreditation, the Asia Pacific Laboratory Accreditation Cooperation, and the national reference laboratories associated to the European Union Reference Laboratory for Heavy Metals in Feed and Food.

Participants were asked to report both the measured value of each heavy metal in question in the sample and the uncertainties associated with those measurements. The results were scored according to international standards.

The outcome of the exercise was generally positive. All of the 57 laboratories that registered reported results. The share of satisfactory scores ranged between 80% and 96%. Participants tended to underestimate the content of total arsenic, and to a lesser extent total cadmium.

Contrary to a previous exercise (IMEP-107 on total and inorganic arsenic in rice), the values reported for inorganic arsenic showed a large spread. Interestingly, this indicates that the matrix (in this case, seafood), has a major influence on the analytical determination of inorganic arsenic. This is a crucial consideration for legislators, because specifying a single maximum level of arsenic in food would appear to not be feasible.

Legislative Situation

In Europe, maximum levels for lead, cadmium, and total mercury in food are laid down in legislation, varying from 0.5 to 1.0 mg per kg for different seafood. No maximum level exists for the methylmercury form of mercury, as its measurement requires specific analytical equipment not routinely present in testing laboratories. However, methylmercury is the main source of human intake of mercury in fish and fishery products, and is important due to its high toxicity compared to inorganic mercury.

No maximum levels for arsenic have been laid down in European legislation either, due to a lack of information about reliable analytical methods for determining inorganic arsenic in different food commodities. In addition, measurement values of inorganic arsenic are generally believed to be method-dependent.

The interlaboratory comparison was, therefore, extended to include methyl- mercury and inorganic arsenic in order to investigate the issues that laboratories encounter in measuring these substances.

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Heavy metals can be toxic for humans when they are not metabolized by the body and accumulate in the soft tissues. Depending on the heavy metal in question, toxicity can occur at levels just above naturally occurring background levels, meaning that consumption of food with a high heavy metal concentration can cause acute or chronic poisoning. Poisoning can result in damaged or reduced mental and central nervous function as well as damage to blood composition, lungs, kidneys, liver, and other vital organs. Long-term exposure to heavy metals may result in slowly progressing physical, muscular, and neurological degenerative conditions as well as cancer.

Arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb), and inorganic tin (Sn) are the most toxic heavy metals that account for most heavy metal poisoning cases. Poisoning is usually a result of environmental pollution or chronic intake of foods high in these metals. Levels of arsenic are usually high in fish and seafood because these organisms absorb and accumulate arsenic from the environment. Cadmium, found in soil because of insecticides, fungicides, sludge, and commercial fertilizers, can contaminate agricultural food products. Some foodstuffs are naturally rich in cadmium, such as liver, mushrooms, shellfish, mussels, cocoa powder, and dried seaweed. Mercury is generated naturally in the environment from volcanic emissions. It is then dispersed across the globe by winds, returning to the earth in rainfall and accumulating in aquatic food chains. Mercury can also contaminate crops sprayed with mercury-containing pesticides.

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Figure 1. Typical sample preparation for metals in foodstuffs.

Food Safety Legislation

Driven by consumer demand and quality, many food agencies have introduced directives that stipulate maximum allowable concentrations for heavy metals in foodstuffs. The European Commission directive 1881/2006 specifies maximum levels for Cd, inorganic Sn, Hg, and Pb in a variety of foodstuffs, with, for example, 0.02 mg Pb/kg allowable in milk products and up to 1.5 mg Pb/kg allowable in bivalve mollusks.

The U.S. Food and Drug Administration (FDA) enforces action levels for poisonous or deleterious substances in human food and animal feed, including cadmium, lead, mercury, and others.1 The FDA has also developed a comprehensive Food Protection Plan to address the challenges and changes occurring in food sources, production, and consumption.2 The plan builds upon advances in science and technology to protect the nation’s food supply from both unintentional contamination and deliberate attack.

An accurate, precise, and robust analytical method is required for measurements of heavy metals in foodstuffs to ensure regulatory compliance, maximum product safety and sustainability, and brand protection. The chosen technique must measure toxic elements, species, and micronutrients, and must also identify whether products have been contaminated during the production process or packaging or by the cooking utensils used to prepare them. Authenticity and origin determinations are also essential. Inductively coupled plasma mass spectrometry (ICP-MS) addresses all these requirements in the most efficient way.

Advantages of ICP-MS

ICP-MS is a high throughput, plasma-based technique with a single high-energy excitation source providing precise determination of heavy metals in foods. The multi-elemental and multi-isotopic nature of the method offers the potential to analyze a whole suite of elements in a single run, saving considerable time and money and allowing faster and more cost-effective decision-making. High linear dynamic range (LDR), another important feature, allows for the simultaneous detection of ultra trace and major elements in one run to obtain comprehensive information about the sample. Trace elements can be determined in a wide range of matrices from parts per trillion (ppt) to low percentage level.

The technology enables food safety laboratories to substantially enhance their productivity, with more than 50 samples analyzed per hour. Other important benefits of ICP-MS include increased sensitivity, a high signal-to-noise ratio, and the flexibility to analyze almost any element in the periodic table. The method offers much lower detection limits compared to graphite furnace atomic absorption (GFAA) and inductively coupled plasma optical emission spectrometry (ICP-OES) while generating less interference than ICP-OES.

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Figure 2. Fully quantitative calibration curves for potassium (K) from 10 to 2,000 parts per million and mercury (Hg) from 0.05 to 10 parts per billion (ppb).

ICP-MS can easily be coupled with separation techniques like liquid chromatography (LC) and gas chromatography (GC), resulting in a literally matrix- independent method capable of performing dependable speciation analyses for toxicological or bioavailability studies. As a multi-isotopic technique, ICP-MS can also provide accurate and precise isotope ration (IR) information, important for authenticity studies or for pinpointing contamination, by verifying the origin of the foodstuff. Because of these benefits, ICP-MS is mandated in standard operating procedures for analyzing heavy metals in foodstuffs.

ICP-MS Regulations

The German Institute for Standardization (DIN) enforces the DIN EN 15765 norm, which specifies a process for the quantification of tin in foodstuffs and canned foods using ICP-MS after pressurized digestion.5 The institute has also introduced the DIN EN 15763 norm, mandating the use of ICP-MS after pressurized digestion for the quantification of arsenic, cadmium, mercury, and lead in foodstuffs.6 The collaborative study performed to develop this norm has included foodstuffs having an arsenic content ranging from 0.06 mg/kg to 21.5 mg/kg dry matter (DM), cadmium ranging from 0.03 mg/kg to 28.3 mg/kg DM, mercury from 0.04 mg/kg to 0.56 mg/kg DM, and lead from 0.01 mg/kg to 2.4 mg/kg DM.

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Table 1. Comparison of the measured and certified concentrations in mg/kg for the four certified reference materials. Meas: Measured value calculated from FQ calibration and back calculated to the solid material according to sample weight taken for digestion and final dilution volume. Cert: Certified value in mg/kg.

Both norms address European Commission legislation EC 1881/2006; they describe the analytical procedure used for metal quantification and outline the sample preparation protocol based on microwave digestion according to the DIN EN 13805 norm.7 This standard specifies a method for the digestion of foodstuffs under pressure that is intended for use in the determination of trace elements. The method has been collaboratively tested in combination with atomic absorption techniques and ICP-MS.

A recent experiment demonstrated the unique capabilities of ICP-MS for measuring heavy metals in foodstuffs according to DIN EN 15765 and DIN EN 15763 standards.

A quadrupole ICP-MS system (XSERIES 2 ICP-MS, Thermo Fisher Scientific) was used for the quantification of heavy metals in foodstuffs. The instrument was operated in mixed-mode, namely with and without the use of the collision/reaction cell technology. It was configured with a sample handling system (SC4 PC3 FAST, Elemental Scientific Inc.). The DIN EN 15765 and DIN EN 15763 norm protocols were used for a number of foodstuffs purchased from a local supermarket and four food matrix certified reference materials (CRMs). A simplified analytical methodology was implemented (see Figure 1).

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Table 2. Comparison of the measured and certified concentrations in mg/kg and % (blue) for the two certified reference materials.

Triplicate microwave digests were prepared for each food, and triplicate procedural blanks were prepared for each microwave batch. External calibration was performed using multi-concentration, multi-elemental standards generated from single element certified stock solutions. Samples were blank subtracted, quantified against the fully quantitative calibrations, and internal standard corrected. The measured concentration was then used to calculate the amount of each element in the original solid foodstuff.

Table 1 presents the data generated for the elements outlined in the EC 1881/2006 regulation and for arsenic for the four CRMs. Due to the multi-elemental capacity of ICP-MS, a number of other elements were simultaneously quantified. The results obtained for the CRMs were in close agreement with the certified values, validating the method and the instrumentation for determining total elemental concentrations in foodstuffs.

A high LDR range was achieved, meaning that the major components of food such as phosphorous (P), sodium (Na), and potassium (K) could be determined in the same run as the minor elements such as Cd and Hg. A calibration of K from 10 parts per million (ppm) to 0.2% and a calibration of Hg from 50 ppt to 10 parts per billion (ppb), both acquired in the same experiment, demonstrate the advantage of the high LDR of ICP-MS (see Figure 2).

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Comparison of the instrumental limits of detection and the limits of detection required by the DIN EN 15763 and 15765 norms. RLD: Required detection limit. CLD: Calculated detection limit of XSERIES 2 with SC4 FAST configuration. *The required detection limit of inorganic tin (Sn) has been estimated from a limit of quantification requirement of 1 ug/L Sn (no isotope specified) in DIN EN 15765.

Table 2 shows the quantitative data for a larger number of analytes and for two of the food CRMs. For all analytes, the measured and certified concentrations are in close agreement. This demonstrates the power of ICP-MS to measure simultaneously at sub-ppb level (Hg, silver, uranium) and percentage level (Na, P, K).

The limits of detection (LODs) required for the EU norms are shown in Table 3. The instrumental LODs, calculated from three blanks (3x standard deviation) are well below the required LODs, demonstrating the suitability of this instrumentation and analytical approach for the determination of trace elements in food according to the EN norms.

Food quality in relation to public safety is a primary concern that has led to the introduction of stringent legislation setting maximum levels of contaminants in foodstuffs. In particular, heavy metals are strictly regulated because their consumption in food is associated with a number of serious health conditions. ICP-MS is a multi-elemental technique, ideal for food safety analysis and the determination of heavy metals in foodstuffs, offering improved sensitivity, increased tolerance to matrix, high linear dynamic range, and high throughput. ■

Dr. Ducos is an ICP-MS application specialist, Dr. Hamester is an ICP-MS product manager, and Dr. Godula is a food safety specialist, all at Thermo Fisher Scientific. For more information, contact Dr. Ducos at shona.mcsheehy@thermofisher.com or +49 (0) 421 5493 227.

References

1. U.S. Food and Drug Administration. Guidance for Industry: Action Levels for Poisonous or Deleterious Substances in Human Food and Animal Feed. Available at: www.fda.gov/Food/ GuidanceComplianceRegulatoryInformation/GuidanceDocuments/ChemicalContaminantsandPesticides/ucm077969.htm. Accessed January 21, 2010.
2. U.S. Food and Drug Administration. Fact Sheet: Food Protection Plan. Available at: www.fda.gov/Food/FoodSafety/FoodSafetyPrograms/FoodProtectionPlan2007/ucm132705.htm. Accessed January 21, 2010.
3. European Commission. Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs. Available at: eurlex.europa.eu/LexUriServ/site/en/oj/2006/l_364/l_36420061220en00050024.pdf. Accessed January 21, 2010.
4. European Commission. Commission Regulation (EC) No 629/2008 of 2 July 2008 amending Regulation (EC) No 1881/2006 setting maximum levels for certain contaminants in foodstuffs. Available at: www.fsai.ie/uploadedFiles/Commission_Regulation_EC_No_629_2008.pdf. Accessed January 21, 2010.
5. German Institute for Standardization. Foodstuffs – determination of trace elements – determination of tin by inductively coupled plasma mass spectrometry (ICP-MS) after pressure digestion; German version EN 15765:2009. DIN. Berlin; 2009.
6. German Institute for Standardization. Foodstuffs – determination of trace elements – determination of arsenic, cadmium, mercury, and lead in foodstuffs by inductively coupled plasma mass spectrometry (ICP-MS) after pressure digestion; German version EN 15763:2009. DIN. Berlin; 2009.
7. German Institute for Standardization. Foodstuffs – determination of trace elements – pressure digestion, DIN EN 13805:2002. DIN. Berlin; 2002.

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