We read the article on bisphenol A released from orthodontic adhesives by Moreira et al in the March 2017 issue with great interest. The authors need to be appreciated for their sincere effort.

In the Material and methods section, an important concern arises with respect to the statement: “For strict adherence to the research protocol, the patients were instructed not to use plastic utensils, such [as] disposable glasses, cutlery, or dishes.” This statement appears unrealistic for the reasons mentioned below.

Apart from plastics, researchers have found that a number of products contain BPA that can be leached into packaged food. It has been shown that BPA can leach from water bottles (polycarbonates) and food cans (epoxy resins) into the packaged foods. This leached BPA enters the digestive tract on consumption of those foods. Furthermore, BPA is present in water sources such as rivers and streams and also drinking water, possibly due to leaching from plastic items in landfills.

Apart from these, BPA is a uniform composition of thermal paper that is used for airline tickets, receipts from automatic teller machines and cash registers, and many other types of receipts in our day-to-day activities. The direct transfer of this chemical from hand to mouth (mouthing behavior) has been proposed to be an important variable for estimating total chemical exposure in humans, particularly in young children.

In keeping with its widespread applications in the manufacture of numerous products, BPA ranks among the highest-volume chemicals manufactured worldwide, with an annual production in 2003 of about 13 billion kg.

It appears clear that BPA is an indispensable chemical in all our daily activities. Hence, it is practically not possible to exclude only plastic utensils as sources of BPA to measure the urinary and salivary BPA levels, as stated by the authors in their study. The application of more stringent criteria would have been useful for assessing the BPA levels.