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Invited Commentary
Feb 25, 2013

New Studies About Everyday Types of Chemical Exposures: What Readers Should Consider: Comment on “A Crossover Study of Noodle Soup Consumption in Melamine Bowls and Total Melamine Excretion in Urine”

Author Affiliations

Author Affiliation: Office of Clinical Toxicology, Specialized Information Services, National Library of Medicine, National Institutes of Health, Bethesda, Maryland.

JAMA Intern Med. 2013;173(4):319-320. doi:10.1001/jamainternmed.2013.2133

Exposures to chemicals in consumer products and from other sources are an everyday reality and have been a global discussion topic and research interest for many years. For example, setting the stage for much of my awareness and thinking about this was a commentary, published in 1979, titled “Analyzing the Daily Risks of Life,” which included extensive mention of chemicals in consumer products.1 That commentary1(p41) began with:

The world seems a very hazardous place. Every day the newspapers announce that some chemical has been found to be carcinogenic, or some catastrophic accident has occurred in some far-off place.

The high level of global interest within the exposure science, toxicology, risk assessment, and risk management communities about everyday types of chemical exposures has continued, and a recent report from the US National Academy of Sciences Committee on Human and Environmental Exposure Science in the 21st Century2 begins with:

We are exposed every day to agents that have the potential to affect our health—through the personal products we use, the water we drink, the food we eat, and the soil and surfaces we touch, and the air we breathe.

In this issue, the Research Letter by Wu et al,3 titled “A Crossover Study of Noodle Soup Consumption in Melamine Bowls and Total Melamine Excretion in Urine,” provides an opportunity to note key considerations when reading about results involving everyday types of chemical exposures. Readers could be asking the following questions for this and other publications:

  1. Is the study published in a peer-reviewed journal? In this case, readers have the easy task of looking for this information and finding the peer-review process for this journal (http://archinte.jamanetwork.com/public/About.aspx).

  2. Are there other publications that lend or do not lend support to the current research, or is this study possibly the first of its kind that suggests an emerging issue for regulators, chemical companies, consumer product manufacturers, and others to consider? Wu et al3 cite 1 publication on melamine in tableware; however, there are many others going back to 1986, if searches of the US National Library of Medicine's PubMed (http://www.ncbi.nlm.nih.gov/pubmed) and TOXLINE (http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?TOXLINE) databases are performed (TOXLINE can be used to also search for PubMed content). Additional relevant publications obtained via PubMed and TOXLINE include “Migration of Melamine and Formaldehyde From Tableware Made of Melamine Resin” (1986)4; “Comparison of the Migration of Melamine From Melamine-Formaldehyde Plastics (“Melaware”) Into Various Food Simulants and Foods Themselves” (2010)5; “Analysis of Melamine Migration From Melamine Food Contact Articles” (2011)6; and “Survey of Counterfeit Melamine Tableware Available on the Market in Thailand, and Its Migration” (2010).7

  3. In addition to scientific journal publications, is there information available from government or other websites that provides perspectives about the exposures and potential risks? The answer is a firm “yes.” As key examples, a web search found that the German Federal Institute for Risk Assessment (BfR) issued an “opinion” in 2011 on “Release of Melamine and Formaldehyde From Dishes and Kitchen Utensils.”8 Later, in 2011, The BfR followed this with a press release titled “Cooking Spoons and Crockery Made of Melamine Resin Are Not Suited for Microwaves and Cooking.”9 The BfR information is valuable and provides information that is globally relevant to scientists, regulators, and others.

  4. How was the study conducted, eg, is it a preliminary or “pilot” study involving a small number of people who were studied, and did the participants represent a narrow or broad, wide range of the types of potentially affected consumers? Considerations relevant to the study by Wu et al3 include the relatively small number of people involved (6 men and 6 women), all noted as being “healthy.”

  5. Did the study use bowls and food that some consumers are likely to be exposed to? If yes, are there geographical or other limitations that should be noted by the authors such as the bowls being likely to be sold only in 1 country or region of the world? Also, is the issue likely to be only with 1 or a few manufacturers of the bowls, or is it likely to be a more widespread issue? Wu et al,3 to their credit, discuss some of this.

  6. Did the study try to approach “reasonably foreseeable” consumer exposure conditions? Considerations relevant to the study by Wu et al3 include the temperatures, exposure durations, type of food being consumed, and other factors. In this study, 500 mL of hot noodle soup with an initial temperature of 90°C was served in a melamine bowl “as a 30-minute breakfast.”

  7. Is there a known or reasonably foreseeable association between these types of exposures and human adverse effects? For example, if the consumer product-type exposures seem to lead to increased melamine excretion in urine, is the level in urine known to be potentially associated with toxic effects in humans? In this case, Wu et al3 note 2 publications that they believe provide information that “a continuous low-dose melamine exposure has been linked to urolithiasis in both children and adults.” An updated search of PubMed or TOXLINE would have found a recent publication from one of the groups (Liu et al10) that continues the discussion.

Readers asking themselves these questions will be in an excellent position to critically evaluate studies about everyday chemical exposures.

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Article Information

Correspondence: Dr Hakkinen, Office of Clinical Toxicology, Specialized Information Services, National Library of Medicine, National Institutes of Health, 6707 Democracy Blvd, Ste 510, Bethesda, MD 20892 (pertti.hakkinen@nih.gov).

Published Online: January 21, 2013. doi:10.1001/jamainternmed.2013.2133

Conflict of Interest Disclosures: None reported.

Disclaimer: The comments by Dr Hakkinen do not necessarily reflect official National Library of Medicine, National Institutes of Health, or other Federal government opinions.

Wilson R. Analyzing the daily risks of life.  Technol Rev. 1979;81(4):40-46Google Scholar
Board on Environmental Studies and Toxicology (BEST).  Exposure Science in the 21st Century: A Vision and a StrategyWashington, DC: National Academies Press; 2012:3
Wu C-F, Hsieh T-J, Chen B-H, Liu C-C, Wu M-T. A crossover study of noodle soup consumption in melamine bowls and total melamine excretion in urine [published online January 21, 2013].  JAMA Intern Med. 2013;173(23):317-319Google Scholar
Ishiwata H, Inoue T, Tanimura A. Migration of melamine and formaldehyde from tableware made of melamine resin.  Food Addit Contam. 1986;3(1):63-693956795PubMedGoogle ScholarCrossref
Bradley EL, Castle L, Day JS,  et al.  Comparison of the migration of melamine from melamine-formaldehyde plastics (“melaware”) into various food simulants and foods themselves.  Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2010;27(12):1755-176420931418PubMedGoogle ScholarCrossref
Chik Z, Haron DE, Ahmad ED, Taha H, Mustafa AM. Analysis of melamine migration from melamine food contact articles.  Food Addit Contam Part A Chem Anal Control Expo Risk Assess21607892PubMedGoogle Scholar
Poovarodom N, Tangmongkollert P, Jinkarn T, Chonhenchob V. Survey of counterfeit melamine tableware available on the market in Thailand, and its migration.  Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2011;28(2):251-25821181596PubMedGoogle ScholarCrossref
Federal Institute for Risk Assessment (BfR).  Release of melamine and formaldehyde from dishes and kitchen utensils. March 9, 2011. BfR Opinion No. 012/2011. http://www.bfr.bund.de/cm/349/release_of_melamine_and_formaldehyde_from_dishes_and_kitchen_utensils.pdf. Accessed November 4, 2012
Federal Institute for Risk Assessment (BfR).  Cooking spoons and crockery made of melamine resin are not suited for microwaves and cooking [press release]. May 5, 2011. http://www.bfr.bund.de/en/press_information/2011/11/cooking_spoons_and_crockery_made_of_melamine_resin_are_not_suited_for_microwaves_and_cooking-70465.html. Accessed November 4, 2012
Liu CC, Wu CF, Wu MT. Reappraisal of melamine exposure and adult calcium urolithiasis [letter].  Kidney Int. 2012;82(3):361-36222791326PubMedGoogle ScholarCrossref