You always ask for a receipt.
A 2010 study found that touching shopping receipts could expose you to potentially cancer-causing levels of a harmful chemical. Researchers found that the thermal paper used by 95% of stores to create receipts contains significant amounts of BPA, which is a hormone-disrupting chemical linked to cancer.
To limit your exposure, ask for a digital copy of receipts that you need or try to limit your skin’s contact with paper receipts.