Food allergen advisory labeling and product contamination with egg, milk, and peanut

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To the Editor:

Allergen advisory labeling (eg, “may contain” and “made in a facility that processes”) used on manufactured products is voluntary, unregulated, and increasingly common.¹ Consumers with food allergy appear to be increasingly ignoring these warnings,² presumably because of frustration and doubt about their legitimacy and risks. Because the labeling is voluntary, consumers might additionally question whether products without such statements are safe, creating further anxiety and frustration. A better understanding of the risks would inform consumers, industry, regulators, and physicians how best to approach this problem.

We designed the current study to simultaneously address three important issues that have not been previously evaluated: (1) to determine the frequency and level of contamination of a large sample of products with advisory labeling for 3 major allergens, (2) to determine whether risks for these 3 foods vary between large and small manufacturers, and 3) to determine the frequency and level of contamination of products that lack advisory labeling but are similar to ones bearing such statements.

A convenience sample of products was obtained from multiple supermarkets in New York and New Jersey, with an initial aim to collect about 100 nonperishable products with any type of advisory labeling for each of 3 allergens, egg, milk, and peanut, among products in 8 categories (see below) known to have higher rates of advisory labeling.¹ An attempt was made to purchase similar products without advisory labeling (“no allergen disclosed”). Large companies were identified as the top 50 on Food Processing Magazine's Top 100 Companies list of August 2007 (http://www.foodprocessing.com/articles/2007/181.html). A particular product was tested for all of the allergens for which there was a reasonable possibility of contamination (based on food category and product lines from the same manufacturer) unless the allergen was disclosed as an intended ingredient. Products labeled as using “Good Manufacturing Practices” for allergens (n = 26) were considered to be among those with no allergens disclosed. A sample from each product was homogenized and analyzed for the presence of egg, milk, and/or peanut as appropriate with Neogen Veratox Quantitative Allergen Tests (Neogen Corp, Lansing, Mich).

The lower limit of detection was 2.5 ppm for each food. The suggested serving size for each product was used to determine the amount per serving in milligrams of the allergenic food. The Fisher exact test was used for statistical analysis; a P value of less than .05 was considered significant.

Despite an exhaustive search attempting to find at least 100 products with advisory labeling for egg, milk, and peanut, only 57 unique products were identified for egg and 59 for milk, whereas 112 were found for peanut. The numbers of “no allergen disclosed” products were 117, 134, and 120 for egg, milk, and peanut, respectively. A total of 599 allergen assays were performed on 401 foods. Assays detected the 3 allergens as follows: egg in 1 (1.8%) of 57 (concentration, 6 ppm) products with egg-advisory statements and 3 (2.6%) of 117 (concentration, 3-8 ppm) products with no allergen declared; milk in 6 (10.2%) of 59 (concentration, 4-222 ppm) products with milk-advisory statements and 4 (3.0%) of 134 (concentration, 17-124 ppm) products with no allergen declared; and peanut in 5 (4.5%) of 112 (concentration, 5-161 ppm) products with advisory statements and 0 (0%) of 120 products with no allergen declared (Table I). Contamination according to product category was as follows: 5 of 80 baking mixes (2 milk and 3 egg, see note below), 4 of 68 chocolate candies (1 milk and 3 peanut), 2 of 11 nonchocolate candies (peanut), 6 of 85 cookies (5 milk and 1 egg), 2 of 81 salty snacks (milk), 0 of 59 cold cereals, 0 of 15 pastas, and 0 of 2 pancake mixes. Overall, contamination levels were greater than 10 ppm (1 mg per 100 g) in 12 of these 19 products. The contaminated baking mixes deserve special note because 3 of them from one supermarket chain used the label phrase “Good Manufacturing Practices were used to segregate ingredients in a facility that also processes peanut, tree nuts, milk, shellfish, fish, and soy ingredients,” which we interpreted to mean that the product was safe for otherwise undisclosed milk, egg, or peanut; however, milk was detected in 2 and egg in 1.

Table I. Food products tested for contamination with egg, milk, and peanut and aggregated outcomes

When serving size was considered, egg contamination was 0.084 to 0.26 mg per serving, milk contamination was 0.13 to 7.3 mg per serving, and peanut contamination was 0.17 to 5.8 mg per serving. Peanut, but not milk or egg, was significantly (P < .05) more likely to be found in products with an advisory statement than in products without. Milk, but not egg or peanut, was significantly more likely to be found in products from small versus large manufacturers. The 7 contaminated products without advisory statements (egg, 3-8 ppm; milk, 17-124 ppm) were from 5 companies; only 1 was from a large company (egg, 7 ppm, or 0.26 mg per serving).

To our knowledge, this is the largest and most comprehensive study to date of frequency of allergen contamination among advisory-labeled products and similar ones without such labels. We found detectable residues of allergenic food in 5.3% of advisory-labeled products and 1.9% of similar products without advisory statements. Among foods from small companies, 5.1% were contaminated compared with 0.75% from large companies. These findings indicate a real risk for consumers and highlight the need to increase awareness among manufacturers, particularly from smaller companies.

It is interesting to consider the clinical relevance of the amount of allergen detected in these products. Unfortunately, allergen threshold levels below which reactions are not provoked are not well established in the literature. The most data are available for peanut. An approach that included modeling a group of 450 patients with peanut allergy with objective symptoms on double-blind, placebo-controlled oral peanut challenge³ recently calculated with 95% certainty that no more than 5% of the population with peanut allergy would react to 3.6 mg of whole peanut. For comparison, our study found 4.5% of advisory-labeled products to have detectable peanut, but considering serving size, only 1 of the 5 contaminated products would have fallen into this risk category (ie, less than 1% overall). For both egg and milk, patients undergoing low-dose diagnostic challenges had mild allergic symptoms in the low-milligram range.⁴ In our study all 4 egg-contaminated products contained less than half a milligram of egg white in a standard serving. However, 7 of the 10 milk-contaminated products we identified fell into the low-milligram range, at which some patients do react, including 3 of 4 products with no allergen declared. More research needs to be done to better define thresholds, and more attention is needed to determine risks and how best to label foods. Based on our data, it is clear that some products pose risks for consumers, and we advocate avoidance of products with advisory statements. Although our data also suggest that many contaminated products are close to and likely below “threshold” levels, we must emphasize that we analyzed only 1 sample per product and thus cannot exclude the possibility that other samples of the same product might have contained higher levels. However, if these low amounts are representative, it implies that changes in manufacturing procedures and more widespread testing might allow production of many more safe products that would not require advisory labeling.

Our study has several limitations. Because we sampled products from certain categories, our results are not applicable across all manufactured foods. At 10.2%, the frequency of milk contamination among advisory-labeled products in our sample was lower than the 42% (34/81) recently found by Crotty and Taylor,⁵ but their study included products from different categories, including more high-risk chocolate products, and tested 2 samples of each product. Similarly, the study by Hefle et al² detected peanut protein in 7.3% (13/179) of products bearing advisory statements compared with our rate of 4.5% (5/112) but also tested 2 lots of each food. The differences between these studies and our findings might be attributable to differences in product and food category selections. Nonetheless, the prior studies also represent convenience samples, and our study provides an important snapshot of the risks among foods with the highest rates of advisory labeling and uniquely includes evaluation of multiple foods and testing of products without advisory labeling.

For consumers with food allergy, effective avoidance is confusing and requires enormous lifestyle upheaval. For industry, prevention of allergen contamination is costly and currently lacks scientific and government guidance. Our study underscores the need for allergic consumers to avoid advisory-labeled products, which present a small but real risk, and to have some concern for products without advisory labeling, particularly from small companies, especially within categories of higher-risk products. Additionally, our observation that most contamination is low-level provides an opportunity for industry and government to work together to further reduce contamination and begin formulating evidence-based guidelines on appropriate labeling to inform of risks.

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References 

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