Precautionary Statement Research Articles

The Expansion of the Hellenic Food Thesaurus; Allergens Labelling and Allergens-Free Claims on Greek Branded Food Products.

Branded food composition databases (BFCDs) are valuable information tools that meet multiple user needs. Recently, recognising allergies and intolerances as an emerging concern for various stakeholders, BFCDs evolve to embed information on allergens. This study aims to expand the Greek BFCD, HelTH, to include allergen information for its 4002 products. A new file was added to the structure of HelTH, and data were curated to record label information. In 68.4% of products, at least one allergen was present in the ingredient list and in 38.9% at least one allergen in a precautionary statement. Milk (38.8%), gluten (32.7%), and soybeans (17.4%) were most commonly declared in the ingredient list; nuts (18.3%), eggs (13.1%), and milk (12.2%) were most commonly declared in precautionary statements. Allergen-free claims were present in 5.3% of the products and referred mostly on gluten and milk. In general, no statistically significant differences were identified between the nutritional composition of allergen-free claimed products and their equivalents. This study delivers an expanded BFCD that provides organised and detailed allergen information; new insights on the presence of food allergens in branded foods and issues of concern regarding allergen declaration that need to be addressed in order to improve label information.

Risk of consuming products with or without precautionary wheat or gluten labelling for persons with coeliac disease

Persons with Coeliac disease (CD) need to keep a lifelong diet without gluten and therefore need to know which foods are safe to eat. The objective of this study was to analyse ordinary foods products without gluten containing ingredients (PWG) with or without the precautionary allergen statement (PAL) “May contain wheat/gluten” or similar wording and use these data to perform a probabilistic risk assessment. Foods with and without PAL were analysed for gluten. Inputs for the risk assessment were analytical results, daily food consumption and data from a 90-days challenge study in coeliac patients (Catassi et al., 2007).20/77 products with PAL and 10/51 without PAL had gluten ≥5 mg/kg 3/77 with PAL and 3/51 without PAL had gluten ≥20 mg/kg. A coconut cookie brand was outlier with 421 mg gluten/kg. The likelihood of developing mucosal damage in the CD population when eating the same PWG for 90 days in addition to certified gluten-free products was low (0.2–3.2%) with little difference between with or without PAL. Including the coconut cookie results increased the risk to 3.8–9.2%.Caution should be taken in connection to foods where there is an obvious chance of contamination.

Allergen's labeling of food products: regulatory practices in Morocco

PurposeAllergenic substances cause food allergy, which represents a major health issue in most countries. This underlines the importance of considering the products' labeling as well as applying related regulatory practices. The objective of this study was to assess the labeling practices of allergens in food products in Morocco.Design/methodology/approachThis cross-sectional survey was conducted on 156 food products collected from four supermarkets in a Moroccan megacity. The data related to the allergen substances (allergen declared, emphasis characters, precautionary allergen labeling) were collected from labels of food products.FindingsThe number of foods included in this research was 156, of which 7 (4.5%) did not mention the allergy alert. The analysis of the allergy alert in the others sample (149) showed 266 nonconformities, noticed in 112 (71.8%) products. The labeling emphasis characters were observed in 33.3% of products, and only 13.5% mentioned “contains allergen” as a mandatory statement to declare the presence of allergens. Allergic alerts found in places concealed, removable by the opening of the seal or difficult to see were observed in 28.9%. The use of a precautionary allergen labeling statement was noticed in 40.4% of products.Originality/valueMoroccan regulations on food allergens are demanding like those of the European Union and more demanding than those of most African countries. However, the application of this regulation remains unsatisfactory and 266 non-conformities were found in 112 (71.8%) products. The absence of emphasis characters and the declaration in inappropriate places represent the most observed non-conformities. Therefore, Moroccan manufacturers must strictly adhere to regulations to avoid exposure of predisposed consumers to potentially threatening allergenic substances.

Regression analysis of unmeasured confounding

Abstract When studying the causal effect of x on y, researchers may conduct regression and report a confidence interval for the slope coefficient β x ${\beta }_{x}$ . This common confidence interval provides an assessment of uncertainty from sampling error, but it does not assess uncertainty from confounding. An intervention on x may produce a response in y that is unexpected, and our misinterpretation of the slope happens when there are confounding factors w. When w are measured we may conduct multiple regression, but when w are unmeasured it is common practice to include a precautionary statement when reporting the confidence interval, warning against unwarranted causal interpretation. If the goal is robust causal interpretation then we can do something more informative. Uncertainty, in the specification of three confounding parameters can be propagated through an equation to produce a confounding interval. Here, we develop supporting mathematical theory and describe an example application. Our proposed methodology applies well to studies of a continuous response or rare outcome. It is a general method for quantifying error from model uncertainty. Whereas, confidence intervals are used to assess uncertainty from unmeasured individuals, confounding intervals can be used to assess uncertainty from unmeasured attributes.

Sesame seed labelling and health protection of allergic consumers

PurposeSesame can cause food allergy and according to European legislation, its presence in food must be declared on the label. The purpose of this paper is to investigate the presence of sesame in food products carrying no mention of sesame on the ingredient label and in food products carrying the voluntary labelling statement “may contain traces of sesame”.Design/methodology/approachPackaged bakery and non-bakery food items were collected at retail. Sample size was calculated according to estimated prevalence of 2 per cent and precision of 5 per cent: in total 32 samples of packaged bakery and non-bakery food were collected for each food category. The RIDASCREEN®FAST Sesame test (R-Biopharm AG, Darmstadt, Germany) was used for the analysis: its limit of detection was fixed in the laboratory at 0.5 ppm.FindingsOf the 32 food samples that did not mention sesame seed on the ingredient label, one (3.1 per cent) breadsticks sample tested positive at a concentration (326 ppm). Of the 32 food samples that carried the precautionary label statement “may contain traces of sesame”, one (3.1 per cent) breadcrumbs sample tested positive (305 ppm). Comparison between the allergen concentration and the published eliciting dose (ED5) for sesame proteins (1 mg) was performed. The calculated exposure was more than 2 the ED05 reported in the literature.Originality/valueTo date, few studies investigating compliance with food-allergen labelling requirements are available. This survey provides data for preliminary risk assessment for sesame allergenic consumers.

Accidental food allergy reactions: Products and undeclared ingredients

Accidental allergic reactions to food are frequent and can be severe and even fatal. We sought to analyze the culprit food products and levels of unexpected allergens in accidental reactions. A prospective cohort study was conducted in adults (n=157) with a physician-confirmed diagnosis of food allergy. During a 1-year follow-up, 73 patients reported accidental allergic reactions and the culprit food products. Food samples received (n=51) were analyzed for a wide range of suspected noningredient allergens, and risk was quantified. A very diverse range of food products was responsible for the unexpected allergic reactions. Thirty-seven percent (19/51) of products analyzed had 1 to 4 culprit allergens identified that were not supposed to be present according to the ingredient declaration. Concentrations varied from 1 to 5000mg of protein of the allergenic food per kilogram of food product and were greatest for peanut, milk, and sesame. Milk proteins posed the highest estimated risk for objective allergic reactions. The intake of culprit allergens by patients varied considerably. For those cases in which culprit allergens were detected, the intake of at least 1 allergen exceeded the reference dose or a culprit allergen with a yet unknown reference dose was present. Both patient neglect of precautionary allergen labeling statements and omission of using a precautionary allergen labeling statement by food manufacturers seem to contribute to accidental reactions. A wide range of food products are causing accidental reactions in patients with food allergy. Eight different allergens not declared on the ingredient lists were detected in the culprit food products, all of which were representative of allergens regulated in the European Union.

Who Do Not Read and Understand Food Label in Malaysia? Findings from a Population Study

Objective: This study determined the prevalence of food label reading and understanding among the Malaysian adults, types of labels being read and factors associated with not reading labels. Methods: Malaysian Adult Nutrition Survey 2014 was a cross-sectional and applied a multistage stratified cluster sampling of living quarters. A total of 4044 adults aged 18-59 years were randomly chosen in selected households to represent the Malaysian adult’s population. Data collection was carried out between March to June 2014. Trained data collectors conducted interview using a validated food label questionnaire to obtain information on whether the respondents read labels (every time they bought or received food) and types of information being read. Complex sample analysis was applied to describe the findings. Result: A total of 2992 respondents (1382 men and 1610 women) answered the questionnaire. About 55.0% of the respondents reported never read labels, sometimes read labels was 22.0% and always read labels was 23.0%. Male sex, lower education, being single (not married/divorced/ widow/widower) and normal weight respondents were significantly less likely to read food label information. Among those who read labels, the expiry date was the most common label information being read (91.8%), followed by the precautionary statement (65.9%). Nutrient information being read was carbohydrate and sugar (21.5%), fat (20.0%) and total energy (14.4%). Nonworking respondents and primary school attainers were significantly less likely not to understand label information. Conclusion: Only half of Malaysian adults read the label when buying or receiving food. Expiry date was the most frequently read information and the prevalence of reading the nutrient information was low. These findings provide useful evidence for the health authorities to plan for nutrition intervention programs in order to increase the food label usage among the relevant target groups.

Allergens labeling on French processed foods – an Oqali study

The French Observatory of Food Quality (Oqali) aims at collecting all nutritional data provided on labels of processed foods (nutritional information and composition), at branded products level, in order to follow nutritional labeling changes over time. This study carries out an overview of allergens labeling frequencies by distinguishing allergens used in recipes from those listed on precautionary statements, for the fourteen allergen categories for which labeling is mandatory according to European legislation. 17,309 products were collected, between 2008 and 2012, from 26 food categories. Products were classified per family and type of brand (national brands, retailer brands, entry‐level retailer brands, hard discount, and specialized retailer brands). Allergenic ingredients were identified from ingredients lists and precautionary statements. 73% of the 17,309 products studied contained at least one allergen in their ingredients list and 39% had a precautionary statement for one or more allergens. Milk (53%), gluten (41%), and egg (22%) were the most commonly used allergens in ingredients lists. For precautionary statement, nuts (20%), egg (14%), peanut (13%), soybean (12%), and milk (11%) were the most common allergens listed. Precautionary statement was most frequently found among first‐price products (hard discount and entry‐level retailer brands). National brands seemed to use it less frequently. For all these results, differences depended both on food categories and allergen categories. This study will enable to follow allergens labeling and their use as ingredients over time, particularly by assessing an hypothetical increase in allergens presence in processed food.

Survey of undeclared soy allergen levels in the most frequently recalled food categories with or without precautionary labelling

ABSTRACTA comprehensive study was designed to determine the frequency and levels of soy allergen in packaged bakery and snack food products. A representative sample of products with no soy allergen disclosed on the label was analysed using two widely used enzyme-linked immunosorbent assay (ELISA) methods. Samples were chosen that either had no soy identified on the product label or which had a soy precautionary statement. Among 558 bakery and snack products, soy protein was detected in 17% of the products using the Neogen (NE) kit and 11% of the products using the Elisa Systems (ES) kit. The disagreement rates between kits were 8.8% for bakery products and 3.3% for snack products. Overall soy protein was detected at higher frequency in bakery products than in snack foods. Among 284 bakery samples, soy protein was detected in 25% of the samples with no precautionary statement and 19% of the samples which had a precautionary statement. Among 274 snack samples, soy protein was detected in 11% of the samples with no precautionary statement and 9% of the samples which had a precautionary statement. The sample repeatability was at an acceptable level (< 9%) for each method and food commodity. The reproducibility between kits was 23% for bakery foods and 36% for snack foods. None of the bakery (21) and snack (6) products without precautionary labelling (measured level > 5 ppm) had a higher level of soy protein per serving compared with the eliciting dose10 (ED10) of 10.6 mg for soy allergic patients. But the level of soy protein per serving may be clinically relevant to a subpopulation of soy allergic patients if a more stringent eliciting dose is applied. These findings emphasise that suitable detection methodologies and references doses are crucial for labelling accuracy and the safety of soy allergic consumers.

Survey of undeclared egg allergen levels in the most frequently recalled food types (including products bearing precautionary labelling)

ABSTRACTSince the number of recalls involving undeclared allergens is commonly associated with bakery and snack foods, we aimed to determine the frequency of egg allergens in a large number of these products using two commercial enzyme-linked immunosorbent assay (ELISA) methods. Samples were chosen that either had no egg identified on the product label or which had an egg precautionary statement. Among all samples, egg protein was detected in 5% of products using a Morinaga (MO) kit and 1% of products using a R-Biopharm (RB) kit. For bakery samples, egg protein was detected in 6% of 363 samples with no precautionary labelling (6% by MO and 1% by RB kit) and 12% of 80 samples which had precautionary labelling. For snack samples, egg protein was detected in 2% of 371 samples with no precautionary labelling (2% by MO and < 1% by RB kit) and 5% of 21 samples which had precautionary labelling. The disagreement rates between two methods were 5.2% for bakery products and 2.6% for snack products. The sample repeatability was at an acceptable level for bakery (< 12.5%) and snack foods (< 7.5%) for each method. The relative standard deviation between test kits was high (103.1%) for bakery foods. Four bakery products without precautionary labelling had a higher level of egg protein per serving compared with the eliciting dose (ED10 of 3.7 mg protein) for egg allergic patients. These results highlight the fact that detection methodology plays a vital role for accurate labelling control and mitigation of risk for egg allergic consumers.

Canadian Policy on Food Allergen Labelling: Consumers' Perspectives Regarding Unmet Needs

It is estimated that 50% of Canadian households are directly or indirectly affected by food allergies. Since accidental exposure to food allergens can cause life-threatening reactions, the need for accurate allergen labelling is key. In Canada, new food allergen labelling guidelines were mandated in August 2012. While a substantial improvement, gaps remain. This study explored the perspectives of directly affected individuals as well as members of the general public regarding their needs and preferences for precautionary labelling, allergen symbols, and suggestions for improving labelling practices in Canada. Eight qualitative focus groups were conducted with directly affected (n=27) and general public (n=24) consumers in Vancouver, Canada. Focus groups were audio recorded and transcribed verbatim for subsequent thematic analysis using NVivo9. Although may contain is recommended by Health Canada, it was the least preferred precautionary statement among research participants. Both participant groups described how many consumers' purchasing habits are indirectly affected by food allergy; hence, their views should be considered in addition to those of directly affected individuals when developing allergen labelling policies. The findings identify future policy needs: 1) mandating and standardizing precautionary/allergen statements and symbols, 2) increased monitoring, and 3) increasing food allergy education and awareness among consumers and manufacturers.

Perceptions of precautionary labelling among parents of children with food allergy and anaphylaxis

To examine the behaviour and perception of parents of food-allergic children with and without a history of anaphylaxis in relation to precautionary labelling on packaged foods and to understand consumers' perception of the "may be present" statement advocated by VITAL (voluntary incidental trace allergen labelling). Questionnaire-based study of parents of a consecutive series of 497 children who attended the Department of Allergy and Immunology at the Royal Children's Hospital, Melbourne, from 1 August to 31 October 2011, of whom 293 met our criteria of having an existing medically diagnosed food allergy, and of whom 246 had enough information provided to be included in our analysis. Parents' responses about their behaviour and perceptions relating to precautionary food labels, and a comparison between parents of children with a past history of anaphylaxis and those with a past history of mild to moderate IgE allergic reactions. Avoidance of foods with precautionary labels differed depending on the wording of the precautionary statement, with 74 parents (65%) ignoring the statement "made in the same factory" compared with 24 (22%) for "may be present". There was no evidence of a difference in participants' behaviour or perceptions depending on whether or not their child had a history of anaphylaxis. Consumers are choosing a gradient level of risk based on the wording of the precautionary statements and appear to be complacent about precautionary labelling. Many statements are now being disregarded by a sizeable proportion of parents of food-allergic children, including those caring for children with a past history of anaphylaxis. This may be due to inadequacies in food labelling legislation. Policies that promote greater clarity and consistent use of precautionary statements may help to deal with this complacency.

SULFA ALLERGY: CROSS-REACTIVITY VERSUS MULTIPLE CONCURRENT ALLERGIES

As a medical resident we have always been taught that there is some sort of cross reactivity between sulfonamide antibiotics and nonantibiotic sulfonamides. Even the manufacturer’s package inserts contain a precautionary statement about possible Cross-reactivity. The most common approach to this problem is avoidance of all sulfa containing drugs. However, there are few data supporting this contraindication. Thus we may be withholding appropriate therapies from patients unnecessarily. To provide a critical and comprehensive review of literature to explore either cross reactivity between sulfonamide antibiotics and nonantibiotic sulfonamides is a fact or fiction and to present an approach to use nonantibiotic sulfonamides in sulfa allergic patients. A PubMed and general medline search was conducted using the individual names of nonantibiotic sulfonamides. We reviewed all of the available case reports and studies regarding sulfonamide antibiotic cross-reactivity with nonantibiotic sulfonamides. Also reviewed the manufacturer’s package insert for each nonantibiotic sulfonamide drug for information concerning possible cross-reactivity with sulfonamide antibiotics. Sulfa drug allergy is one word holding the whole cross-reactivity theory in it. It should be obsolete from the medical dictionary. This one word is complicating the medical decision-making. Allergies should not be attributed to classes or groups of drugs unless proven. After reviewing all the available literature we can conclude that assumptions about cross-reactivity are a FICTION.

Precautionary allergen labelling following new labelling practice in Australia

We aimed to assess the prevalence and types of precautionary labelling statements for common food allergens on the packages of products for which these allergens were not listed as an ingredient and to investigate the uptake of the Voluntary Incidental Trace Allergen Labelling, a new risk management tool developed in Australia to assist with declaring the possible presence of allergens in food products by manufacturers. We also aimed to examine changes in the prevalence of precautionary labelling for egg, peanuts and tree nuts over a 3-year period. All packaged processed goods in a large supermarket in Melbourne, Australia, were examined for precautionary labelling between May and July 2011. In total, 1355 products were investigated. Overall, 882 products (65%) had a precautionary statement for one or more allergens. The most common allergens listed on precautionary statements were tree nuts (36.2%) and peanuts (34.1%), followed by sesame (27.5%) and egg (22.6%). Of those that had precautionary statements, 'May contain traces of …' was the most common type of precautionary label used on 392 products (29.0%). This was followed by 'May be present' on 172 products (12.7%). The use of precautionary labelling for peanut, tree nuts and egg remained high. The uptake of the Voluntary Incidental Trace Allergen Labelling 'May be present' statement was low in comparison with other precautionary statements, but there has been an increase since 2009.

Analysis on descriptions of precautionary statements in package inserts of medicines

BackgroundTo prevent medical accidents, users must be informed of the cautions written in medical package inserts. To realize countermeasures by utilizing information systems, we must also implement a drug information database. However, this is not easy to develop, since the descriptions in package inserts are too complex and their information poorly structured. It is necessary to analyze package insert information and propose a data structure.MethodsWe analyzed the descriptions of ‘precautions for application’ in package inserts via text mining methods. In order to summarize statements, we applied dependency analysis to statements and visualized their relations between predicate words and other words. Furthermore, we extracted words representing timing to execute the order.ResultsWe found that there are four types of statements: direct orders such as “ ” (use), causative orders such as “ ” (make someone use), direct interdictions such as “ ” (do not use), and causative interdictions such as “ ” (do not make user use). As for words representing timing, we extracted six groups: ”at the time of delivery,” “at the time of preparation,” “in use,” “after use,” and “at the time of storage.” From these results, we obtained points of consideration concerning the subjects of orders in the statements and timing of their execution.ConclusionFrom the obtained knowledge, we can define the information structure used to describe the precautionary statement. It should contain information such as the actions described in the statement, the flag to express an order or interdiction, the subject to be ordered, and the timing.

The Allergen Bureau approach to allergen cross contact risk assessment – our journey

The Allergen Bureau was established in 2005 and is funded by membership from the Australian and New Zealand food industry. The industry developed Guide to Allergen Management and Labelling is a resource to ensure consistency in manufacturing practices and labelling. VITAL (Voluntary Incidental Trace Allergen Labelling) is a risk tool that was developed against a regulatory background where the labelling of incidental trace cross contact allergens is not mandated. VITAL is a risk based methodology to be used in assessing the impact of allergen cross contact and stipulates a consistent precautionary allergen labelling statement. Application of the VITAL system aims to avoid indiscriminate use of precautionary labelling and contribute to the minimisation of risk to allergic consumers. VITAL uses an action level grid to assist in determining if the presence of residual protein from allergenic substances through cross contact requires precautionary labelling. VITAL is based on the premise that some products may have foreseeable levels of an allergen present through incidental cross contact, and this will not be labelled where the level is below a specified action level. Due to the wide use and international interest in VITAL, it is important that VITAL be reviewed regularly to ensure that it can be considered to be the best available tool for cross contact allergen risk management. The purpose of this presentation is to provide information on the status of VITAL today and to outline the review process currently underway .A significant element in this process is the establishment of a scientific expert panel to review current clinical data, population data, and to consider the application of probabilistic modelling to the current action levels. This expert panel will meet in Australia in January 2011 and we hope to be able to report on the outcomes of the first meeting and the next steps in the journey .A consistent approach to cross contact risk assessment is key to ensuring reliability of labelling and consumer confidence and safety.

Role of food labels in accidental exposures in food-allergic individuals in Canada

Little is known about the impact of food labeling on the allergic consumer. To determine the proportion of food-allergic individuals attributing an accidental exposure to inappropriate labeling, failure to read a food label, or ignoring a precautionary statement and to identify factors associated with accidental exposures. Food-allergic individuals or their caregivers were recruited from a Canadian registry of individuals with a physician-confirmed diagnosis of peanut allergy and from allergy awareness organizations. Participants completed questionnaires regarding accidental exposures due to specific food labeling issues. The association between accidental exposures and characteristics of food-allergic individuals or their caregivers was estimated using multivariate logistic regression models. Of 1,862 potential participants, 1,454 (78.1%) responded. Of the 47.8% (95% confidence interval [CI], 45.1%-50.5%) of respondents who experienced an accidental exposure, 47.0% (95% CI, 43.1%-50.9%) attributed the event to inappropriate labeling, 28.6% (95% CI, 25.1%-32.2%) to failure to read a food label, and 8.3% (95% CI, 6.3%-10.7%) to ignoring a precautionary statement. Food-allergic individuals who were allergic to peanut, tree nut, fish, or shellfish were less likely to experience an accidental exposure due to the allergen not being identified in plain language. A considerable proportion of accidental exposures are attributed to inappropriate labeling, failure to read labels, and ignoring precautionary statements. Clear and consistent labeling of food allergens combined with increased consumer education is necessary to improve consumer confidence and compliance and to reduce accidental exposures.

Vaginal birth after cesarean section: Is suspected fetal macrosomia a contraindication?

The American College of Obstetricians and Gynecologists' "Guidelines for vaginal delivery after a previous cesarean birth" include a precautionary statement regarding estimated fetal weight of more than 4000 g. To evaluate the validity of this restriction, we conducted an analysis of the outcomes of 301 trials of labor with birth weights equal to or greater than 4000 g. In the birth-weight range of 4000-4499 g, 139 of 240 patients (58%) delivered vaginally. In the group with birth weights exceeding 4500 g, 26 of 61 patients (43%) delivered vaginally. When compared with 1475 trials of labor with birth weights under 4000 g, no significant differences in perinatal or maternal morbidity were found. Comparison with a control group of 301 women with no previous uterine surgery who delivered macrosomic infants also demonstrated no significant differences in perinatal or maternal morbidity. The medical literature does not support elective cesarean section for suspected fetal macrosomia in nondiabetic women, and based on our experience, there appears to be no reason for treating previous-cesarean mothers differently.

Trimethoprim-sulfamethoxazole for cholangitis followinghepatic portoenterostomy for biliary atresia

country can be found in the Table? Because of the potential for salicylate absorption, these products probably should not be given to persons taking oral anticoagulants, probenecid, methotrexate, or medications containing other forms of salicylate such as aspirin. Use of these products probably should be avoided by young children and by persons with hemophilia or with sensitivity to salicylates. Although we detected no bismuth in serum or urine specimens, it is not possible at the present time to state categorically that there is no absorption of bismuth from bismuth subsalicylate preparations. A recent report (10) indicates absorption of bismuth into bone in patients who were receiving long-term therapy with orally administered bismuth salts. This requires additional study. The labels on these products do not indicate the potential for salicylate absorption. Manufacturers should be required by the appropriate regulatory agencies in all countries to include an informative and precautionary statement. The Bureau of Drugs of Canada has recently requested that these label changes be made by the makers of Pepto-Bismol, Rawleigh Pleasant, Watkins Settelz, and Stress liquid, which are bismuth subsalicylate containing compounds available in Canada5 ~ These agencies should also review all data upon which the present label recommendations were made.

Chromatographic Detection of Flavor Additives in Vanilla Extract

Abstract A second collaborative study was conducted on a thin-layer chromatographic method for the detection of flavor additives, adopted as official, first action last year. Fifteen collaborators reported successfully on the presence of added flavoring materials in fovir unknown samples. Some collaborators found significant variations in the activity of the Silica Gel G used to make the thin-layer plates, and a precautionary statement has been inserted in the method to detect svich inactive or overactive reagents. As a result of this study, the thin-layer method has been recommended for adoption as official, final action.