title: Lead glass
context: Items made of lead glass may leach lead into the food and beverages contained.[21][22] In a study performed at North Carolina State University,[23] the amount of lead migration was measured for port wine stored in lead crystal decanters. After two days, lead levels were 89µg/L (micrograms per liter). After four months, lead levels were between 2,000 and 5,000µg/L. White wine doubled its lead content within an hour of storage and tripled it within four hours. Some brandy stored in lead crystal for over five years had lead levels around 20,000µg/L.[24][25] To put this into perspective, the U.S. Environmental Protection Agency's lead standard for drinking water is 15µg/L, which is equivalent to 15 parts per billion.[26] Citrus juices and other acidic drinks leach lead from crystal as effectively as alcoholic beverages.[27][28] Under conditions of repeated use of the decanter, the lead leaching steeply decreases with increasing use. This finding is "consistent with ceramic chemistry theory, which predicts that leaching of lead from crystal is self-limiting exponentially as a function of increasing distance from the crystal-liquid interface."[28] Lead leaching still occurs, but the quantity that leaches into a glass of wine or other beverage left standing for a few hours is much smaller than the quantity of lead consumed daily in ordinary diet.
question: How much lead is safe to drink?
answers: 15µg/L