Flour, Pasta, Pastes and Clay: Keeping Safe in School

By The Boston Children’s Hospital Celiac Team

Further research from Children’s National in Washington D.C. and Boston Children’s Hospital is providing more data regarding the risk of gluten exposure in schools. The recently released paper, “A Quantitative Assessment of Gluten Cross-contact in the School Environment for Children with Celiac Disease” in the Journal of Pediatric Gastroenterology and Nutrition helps to answer common questions about how to keep children who require gluten-free (GF) diets safe at school. Below, we review and summarize this important research and share our team’s recommendations based on this new information.

The authors tested four scenarios where it was thought that gluten transfer could be high enough to lead to cross-contact, resulting in a gluten-free food having a gluten concentration greater than 20 parts per million (ppm). This threshold was chosen because food containing less than 20 ppm (less than 0.002 percent gluten) is considered to be “gluten-free” by the U.S. Food and Drug Administration, and can be labelled “gluten-free” in the United States, Canada and the European Union. The scenarios tested were:

  • Playing with modeling clay: Play-doh contained over 32,000 ppm gluten, which is nearly as much as in wheat bread. Even when children did not wash their hands, there were no cases of gluten transfer from hands to a slice of GF bread resulting in a gluten concentration >20 ppm. In two cases, bread wiped on the table surface with visible contamination had gluten levels >20 ppm.
  • Sensory tables with dry and wet pasta: After children played with wet pasta in sensory tables, 9/10 children had visible contamination on their hands that transferred to GF bread resulting in a gluten concentration >20 ppm. The child who did not have any transfer did not like the feel of the pasta and had minimal contact. Playing with dry pasta did not produce detectable gluten transfer.
  • Papier mâché – All 10 children who used papier mâché had a significant amount of residue and transferred high amounts of gluten to GF bread.
  • Baking project: Thirty children rolled gluten-containing dough and cut out cookies on a surface dusted with gluten-containing flour. After washing hands with water, soap and water or wet wipes, gluten transfer from hands to a slice of gluten-free bread was detectable for 11/30 participants. Gluten transfer from the surface occurred more than 70% of the time, even after surfaces were washed.

Traditionally, we have made recommendations about avoiding cross-contact based on assumptions and expert opinion, but with very little actual data. This is the first study to examine common educational activities, and it provides useful data to help guide assessment of the risk of cross-contact and to advise our patients with celiac disease (CD).

We would like to share with you our recommendations based on this work.

Modeling Clay:

  • Children with CD (and others who follow a GF diet) should use GF modeling clays.
  • Play-doh brand modelling clay is wheat-based and contains significant amounts of gluten. It should not be eaten or played with by children who may eat the Play-doh, put their hands in their mouth or engage in other behaviors that put them at risk of ingestion.
  • When GF modelling clay is not available and children are not at risk of ingestion, play in a supervised setting with scrupulous cleaning of hands and surfaces to remove all visible contamination is likely to be safe.


  • Children with CD (and others who follow a GF diet) should use GF pasta for art and other classroom projects.
  • Gluten-containing dry pasta appears to pose a low risk unless there is oral exposure.
  • Gluten-containing wet pasta (e.g. sensory tables) tends to adhere to hands and other surfaces and poses a much higher risk of environmental contamination and gluten exposure than dry pasta.

Gluten-containing flour, powders and pastes:

  • Children with CD (and others who follow a GF diet) should only work with GF flours, powders and pastes (such as papier mâché)
  • In classroom environments, there is a risk if gluten flours are used. This risk is related to aerosolization of flour, spread of flour dust, residual flour when surfaces are not cleaned adequately, and unanticipated contact (e.g., spills, food fights).
  • Use of gluten-containing liquids (e.g., pancake mix) or wet pastes is a risk for gluten contamination because it can be difficult to remove all traces of gluten from hands and work surfaces.

It is important to recognize that handwashing and environmental decontamination practices are highly variable, particularly among children and in busy classroom environments. While thorough cleaning procedures are effective for removing gluten from most surfaces, it may be challenging to ensure that these occur consistently.  As well, it is important to consider the developmental stage of the individual child and how this might affect their exposure risk.  For example, some children suck their thumb or put their hands or other objects (including Play-doh) in their mouth.

  • Surfaces should be cleaned adequately before a child with CD works in an environment where wheat flour or wet gluten-containing materials have been used.
  • Adequate supervision is essential when gluten-containing materials are being used in the classroom setting.
  • Hand washing is important.
  • Food should never be eaten if there is visible contamination on hands, surfaces or the food itself.

Clear communication with daycare or school regarding CD, including the need for a GF diet and maintenance of a safe environment, is crucial. In addition to these conversations, a formal 504 plan or Individual Health Plan (IHP) may be helpful for the student with CD.

Article Link

The Boston Children’s Hospital Celiac Team:
Janis Arnold, LICSW
Sophie Burge MS, RDN, LD
Alan Leichtner, MD
Tara McCarthy, MS, RDN
Randi Pleskow, MD
Jocelyn Silvester, MD PhD
Dascha C. Weir, MD
Sharon Weston, MS RD, LDN

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