Handling of Thermal Receipts as a Source of Exposure to Bisphenol A

Human exposure to bisphenol A (BPA) has been associated with adverse health outcomes, including reproductive function in adults¹ and neurodevelopment in children exposed perinatally.² Exposure to BPA is primarily through dietary ingestion, including consumption of canned foods.³ A less-studied source of exposure is thermal receipt paper,⁴ handled daily by many people at supermarkets, ATM machines, gas stations, and other settings. We hypothesized that handling of thermal receipts significantly increases BPA exposure, but use of gloves during handling minimizes exposure.

In 2010-2011, after obtaining written informed consent, we recruited Harvard School of Public Health students and staff (aged >18 years, nonpregnant) via informational fliers and e-mail. No sample size calculation was performed for this pilot study, which was approved by the Harvard University institutional review board.

We used a simulation cross-over study design. At the first simulation, participants printed and handled receipts continuously for 2 hours without gloves. After a washout period of at least 1 week, a second simulation was conducted in which participants repeated handling of receipts wearing nitrile gloves. The option to participate in the second simulation or to provide sequential urine samples following the first simulation was offered to all participants at study entry.

All participants provided a spot urine sample, collected in a sterile BPA-free polypropylene specimen cup, immediately before handling of receipts and 4 hours later. Volunteers provided additional sequential urine samples at 8, 12, and 24 hours after handling of receipts without gloves. Urinary-specific gravity was measured using a handheld refractometer. Urine was stored in polypropylene cryogenic vials at or below −20°C until analysis. Total (free plus conjugated species) urinary BPA concentration was measured at the US Centers for Disease Control and Prevention using published methods.¹ Concentrations of BPA were adjusted for specific gravity to account for urine dilution.

Using SAS version 9.3 (SAS Institute Inc), mixed regression models were used to examine associations between log-transformed specific gravity–adjusted urinary BPA concentrations for prehandling and posthandling samples and across time points for those who provided sequential urine samples. Statistical significance was set at a P ≤ .05 (2-sided test).

Twenty-four volunteers (mean age [SD], 35 [12] years) provided at least 2 urine samples for the simulation without gloves; 12 volunteers provided additional sequential samples and 12 also completed the simulation with gloves (Table). We excluded 1 participant for reporting consumption of 4 cans of beverage prior to the simulation (baseline urinary BPA concentration of 49.3 μg/L vs <2 μg/L for the remaining participants, decreasing to 12.0 μg/L postsimulation).

We detected BPA in 83% (n = 20) of samples at baseline and in 100% of samples after handling receipts without gloves. The geometric mean urinary BPA concentration was 1.8 μg/L (95% CI, 1.3-2.4 μg/L) before simulation and 5.8 μg/L (95% CI, 4.0-8.4 μg/L) postsimulation (P = .005 for interaction between presimulation and postsimulation BPA and glove status). The geometric mean BPA urinary concentrations from 12 participants who provided sequential samples following receipt handling without gloves were 2.1 μg/L (95% CI, 1.4-3.3 μg/L) at baseline, 6.0 μg/L (95% CI, 3.4-10.7 μg/L) at 4 hours, 11.1 μg/L (95% CI, 5.5-22.8 μg/L) at 8 hours, 10.5 μg/L (95% CI, 4.9-22.6 μg/L) at 12 hours, and 4.7 μg/L (95% CI, 2.4-9.1 μg/L) at 24 hours. Each measure was significantly different from baseline (P < .001 for 4-hour, 8-hour, and 12-hour urine samples and P = .04 for 24-hour samples). We observed no significant increase in urinary BPA after handling receipts with gloves (Figure).

In this pilot study, we observed an increase in urinary BPA concentrations after continuously handling receipts for 2 hours without gloves, but no significant increase when using gloves. The peak level (5.8 μg/L) was lower than that observed after canned soup consumption (20.8 μg/L).³ The clinical implications of the height of the peak level and the chronicity of exposure are unknown, but may be particularly relevant to occupationally exposed populations such as cashiers,⁵ who handle receipts 40 or more hours per week.

Limitations include the small volunteer sample and loss of participants in the second simulation. However, urinary BPA concentrations at baseline were similar in the full and smaller groups and similar to the US population (1.83 μg/L).⁶ A larger study is needed to confirm our findings and evaluate the clinical implications.

Corresponding Author: Shelley Ehrlich, MD, ScD, MPH, University of Cincinnati College of Medicine, 3333 Burnet Ave, Cincinnati, OH 45229 (shelley.ehrlich@cchmc.org).

Author Contributions: Dr Ehrlich had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Ehrlich, Smith, Hauser.

Acquisition of data: Ehrlich, Calafat.

Analysis and interpretation of data: Ehrlich, Calafat, Humblet, Smith, Hauser.

Drafting of the manuscript: Ehrlich, Humblet, Hauser.

Critical revision of the manuscript for important intellectual content: Ehrlich, Calafat, Humblet, Smith, Hauser.

Statistical analysis: Ehrlich, Humblet, Hauser.

Obtained funding: Ehrlich.

Administrative, technical, and material support: Ehrlich, Calafat.

Study supervision: Ehrlich, Calafat, Hauser.

Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.

Funding/Support: This project was supported by grant 2 T42 OH008416-05 from the Harvard-NIOSH Education and Research Center.

Role of the Sponsor: The Harvard-NIOSH Education and Research Center had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention (CDC). The involvement of the CDC was determined not to constitute engagement in human subjects research.

Additional Contributions: We thank Lori Torf (Harvard School of Public Health cafeteria) for providing us with access to the cafeteria cash registers for the simulations. We also thank the Hauser staff for assistance with storage of samples and supplies, Greg Wagner, MD (Harvard School of Public Health), for his advice and support at the start of the study, and Xiaoyun Ye, MS, Xiaoliu Zhou, MS, Tao Jia, MS, and Joshua Kramer (all 4 with the CDC) for technical assistance in measuring urinary bisphenol A. None of the individuals acknowledged were compensated for their contributions.