This is a myth. Sort of.
You probably know that pewter is an alloy. You may also know that it can contain lead, but not always. Pewter is mostly tin; the minority metal can be copper, antimony, brass, zinc, bismuth or lead. A Winterthur Museum study from the 1970s showed that fine quality 18th-century pewter contained no lead, but lower quality pewter often did.
Virtually everyone was exposed to pewter in the form of plates, utensils, and drinking vessels. Even well-to-do folks who could afford sterling and glass on their dining tables were exposed, because pewter was used in their kitchens. Those who couldn’t afford sterling and glass—that is, the vast majority of the population–used pewter on tables and in kitchens.
The noxious effects of lead taken internally were well known in the colonial period, if not well understood. Lead poisoning was recognized back in the days of ancient Rome, when it became obvious that men who worked directly with lead, like miners and plumbers, suffered from its symptoms. All colonial Americans came into daily contact with lead through pewter, lead-glazed pottery, lead crystal, musket balls, lead paint, lead solder, and other sources. Ironically, the richer the person, the more lead he or she consumed, since servants, slaves, and the poor ate with wooden utensils.
Scientists at the Smithsonian did some interesting work analyzing the lead content in colonists’ bones. For comparison purposes, they noted that modern Americans generally have less than 20 parts per million of lead in their bones, and it takes about 50 parts per million before symptoms become noticeable. The bones of one wealthy Virginian who lived in the mid-17th century yielded a whopping 149 ppm. “But,” say Robin Kipps and Sharon Cotner of Colonial Williamsburg’s Apothecary, “there is no way to determine how much of the lead in a body was due to pewter versus all the other sources.” It seems safe to say that pewter contributed to lead poisoning but was not the most significant source of lead.
Did the colonists realize the lead in their pewter played a role in their health problems? Almost certainly not. Kipps and Cotner note that medical texts of the period do not make the connection between lead poisoning and the use of pewter, crystal, and ceramics, so presumably no one else did either.
Pewter gradually faded from use. Beginning in the mid-eighteenth century, it was replaced by ceramic plates and glass drinking vessels made widely available through the efficiencies of mass production. Many ceramic glazes contained lead.
Don’t worry about using any modern pewter you may own. Modern pewter, used mostly in decorative pieces, is entirely lead free and usually marked as such. Antique pewter is riskier, since there is no easy way to tell if its content includes lead. (I’ve been told that you can buy a lead test kit at hardware stores and that it’s a fairly simple test, but never tried it myself.)