February 25, 2014

expert reaction to new study into BPA in urine following the handling of till receipts

A study in JAMA found participants who handled till receipts printed on thermal paper continuously for 2 hours without gloves had increased levels of bisphenol A (BPA) in their urine compared to participants who wore gloves.

Prof Alan Boobis, Professor of Biochemical Pharmacology, Imperial College London, said:

“This study provides additional information on dermal exposure to bisphenol A (BPA) via handling of thermal receipt paper.  However, it would be premature to conclude that those handling such receipts were at increased risk due to BPA exposure from this activity.  The authors conclude that a larger study is needed to confirm the findings and evaluate the clinical implications.  Certainly, from the present study one cannot reach any clear conclusions on exposure or risk from BPA following handling of thermal receipts.

“Whilst exposure via the dermal route bypasses pre-systemic metabolism in the liver, nevertheless as only total (free + conjugated) BPA was measured in the urine samples, it is not possible to determine what was the increased target tissue exposure to free BPA in this study and for how long this occurred.

“Spot urine samples were used for measurement of BPA.  This is not ideal, as the relationship between systemic exposure and levels determined in spot urine samples is not as good as one would wish.

“The average increase in urinary total BPA after handling the receipts continuously for 2 h was 3-fold. How does this simulation compare with real-world behaviour?  What would be the increase in BPA in workers using thermal receipts through usual workplace activity? 

“On a technical note, the study design did not randomise whether gloves were used or not.  Hence, it was not possible to exclude period effects from the study.  Study design was somewhat unbalanced, with only 12 subjects completing the ‘with glove’ phase, compared to 24 in the ‘without glove’ phase.”

Prof David Coggon, Professor of Occupational and Environmental Medicine, MRC Lifecourse Epidemiology Unit, University of Southampton, said:

“That handling thermal paper can cause exposure to BPA is not surprising.  What matters is the extent of the exposure that results, and whether it is sufficient to cause any risks to health.  The preliminary results presented in this paper suggest that exposures from intensive handling of thermal paper over two hours are well below a safety level that the European Food Safety Authority has recently proposed would not be expected to result in harm to health.  However, the US study is only a small preliminary investigation, and the potential for occupational exposures would be worth checking out by further research.”

Prof Warren Foster, CIHR/Ontario Women’s Health Council Professor & Director, and Department of Obstetrics & Gynecology, McMaster University, said:

“This is a rather narrowly focused paper that really adds very little to the literature other than to demonstrate that, under simulated conditions, cash register receipts are another potential source of BPA. However, the paper does not provide any insight into the impact of this exposure on circulating concentrations of free BPA (the biologically active form). BPA absorbed through the skin could undergo local biotransformation to inactive forms of BPA with no meaningful subsequent increase in circulating concentrations of BPA; an issue not evaluated or discussed in this paper. Finally, the authors of the paper did not undertake any health measures in this study and thus cannot comment on any potential health implications of the increase in total BPA measured in the urine of the study subjects in this paper. Therefore, this paper provides a negligible increase in our knowledge. Moreover, it is my conclusion that, in the absence of data on circulating concentrations of free BPA or evidence of a health effect, the paper doesn’t merit any media attention.”

Prof Tony Dayan, Emeritus Professor of Toxicology, University of London, said:

“That BPA would be absorbed across the skin is not surprising as it has long been known that its chemical nature would permit that route of uptake and some of that chemical would be excreted in urine regardless of how it got into the body.

“The study results, as briefly summarised in the Press Release, claim increased frequency in its urinary excretion from 83% to 100% of 24 subjects who handled ‘Thermal Paper’ continuously for 2 hours, i.e. an increase of 4 subjects from 20 to 24.

“How close to real life exposure at work was ‘Continuous handling for 2 hours’? Consider how a till operator normally works – handling a receipt forms a very brief part of the work and it is intermittent, certainly not ’40 hours a week’.

“The ‘importance’ of the urinary BPA concentrations then found should be compared with the authors’ own data about the much higher urinary levels after consuming only 1 can of soft drink and in a very large general population study they cite – the NHANES survey.

“Exposure to BPA above a certain level has been associated with the harmful effects mentioned in animals but it is not correct just to state there is good evidence for all the harmful effects suggested in humans. That is a hotly contested subject as shown, for example, in the recent lengthy report on BPA by the European Food Standards Agency, which made a much more guarded assessment of the potential risk to humans.”

‘Handling of Thermal Receipts as a Source of Exposure to Bisphenol A’ by Ehrlich et al., published in JAMA on Tuesday 25 February