Nearly 5,000 USB pen drives are put through washing machines in local drycleaners each year, claims a survey.
And consumers leave 10,000 handheld electronic devices in the back of taxis every year, according to the research by security supplier Credent Technology.
This could be a massive money maker for the Information Commissioner's Office (ICE), says the firm.
From 16 April, new powers given to the ICO will fine companies half a million pounds for the loss of data leading to a major security breach.
Sean Glynn, vice president at Credant Technologies, said: If sensitive or valuable data is being carried, then people should protect it with encryption to prevent unauthorised access at any point.
The same survey conducted a year ago shows that the number of lost pen drives has halved. Credant believes that customer data is instead being stored on newer smart phones and netbooks - two devices which have greatly increased in popularity over the past year.
Glynn said: "Although this study shows a positive drop in the number of lost memory sticks, we would urge users to take more care than ever not to download unprotected customer details and other sensitive information."
Credant says that companies should balance the advantages of mobile computing and flexible working with ways of protecting the organisation's data and avoiding fines.