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People in Boston drink so much coffee that the Massachusetts Water Resources
Authority want to use caffeine to trace the path of their bodily wastes off the
New England coast. Water engineers usually look for high levels of ammonia or
nitrogen when they want to locate leaking pipes or work out how quickly waste
dissipates off the coast. But Robert Chen of the University of Massachusetts in
Boston says that while ammonia can originate in, say, cleaning products,
caffeine is far more specific to human waste. Even “if you dumped a boatload of
tea in the harbour”, he says, “it…