Hand-to-mouth and other hand-to-face touching behavior in a quasi-naturalistic study under controlled conditions

ABSTRACT

Data gaps exist in our understanding of hand-to-mouth touching behavior among adults, despite its relevance for accurately characterizing inadvertent ingestion exposures to chemical and pathogenic microbial agents and consequent associated health risks. The present study describes detailed observations of the frequency and nature of hand-to-mouth and other hand-to-face touching behavior among 14 male and female volunteers in a controlled, quasi-naturalistic setting. Participants performed four 15-min tasks: 1) installation of a brass object as part of a short home improvement project, 2) completion of a pen-and-paper survey, 3) engagement in a telephone conversation, and 4) use of headphones to listen to music. Video recordings of the participants performing each task were reviewed and coded for touches to the face with emphasis on specific regions of the face and palmar versus dorsal contacts. During the installation task, only one of the 14 participants was observed touching his face; this was to the nose, on two separate occasions. Summed across the three non-installation tasks, including palmar and dorsal contacts, participants touched their lips, their mouth, and anywhere on their face on average (range) 5.1 (0–19), 0.4 (0–3), and 27.7 (6–49) times, respectively. Facial contacts during these three non-installation tasks were predominantly with the palmar surface of the hand. The implications of these data are contextually specific, as the potential health impacts of face touching behavior among adults might differ based upon toxicity or virulence of hand contaminants of interest.

KEYWORDS:

• Behavior
• exposure science
• hand-to-mouth
• hand-to-face
• inadvertent ingestion

Acknowledgments

We thank Christine Wood for offering her expert guidance and past experience in the design, execution, and analysis of the study; Jeremy Schwark for his assistance with the tallying and analyzing the data; and Asha Decker for her support in preparing the study, as well as with the collection of the data.

Declaration of interest

The authors prepared this manuscript during the normal course of their employment with Exponent, Inc., a multi-disciplinary company that provides scientific consultation and expert testimony to private and public clients. Renee Kalmes and Robert Rauschenberger have served as expert witnesses on hand-to-mouth behavior. National Manufacturing Co., Inc. did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Additional information

Funding

This work was funded, in part, by National Manufacturing Co, Inc. All other work was funded by Exponent, Inc. during the normal course of the authors’ employment.