MANILA, Philippines–Be wary of the souvenirs you buy for the papal visit, because these could contain harmful amounts of toxic lead.

This was the message of environmental advocacy group EcoWaste Coalition after it found out that metal pendants attached to papal visit souvenirs such as bracelets and necklaces are partly made up of lead, a toxic metal that could affect mental growth.

In a statement released upon Pope Francis’ arrival on Thursday, EcoWaste said that so-called pewter pendants in the shape of the papal cross and of Pope Francis’ face had alarmingly high levels of lead.

“Most papal souvenirs that we have screened for lead are thankfully nontoxic. Pope Francis, who has a master’s degree in chemistry, would be happy to know that many faith-inspired products are safe from such poisons and generally pose no risk to human health and the environment,” said Thony Dizon, an EcoWaste project coordinator.

These products include button pins, wooden wrist rosaries, small cards with the image of a saint printed on them, calendars, T-shirts, bag tags, ID laces, refrigerator magnets and ballpens.

“However, we got the shock of our life to discover souvenir items with pewter or pewter-like pendants of Pope Francis and the Papal Cross that had dangerous levels of lead. Some are of a size that could be swallowed easily by children” he said.

Pewter is a type of metal alloy that is typically composed of metals such as tin and other common metals.

EcoWaste said they found this out after subjecting the souvenir items to a process called X-ray fluorescence, which can reveal the chemical composition of the subject items.

Their tests showed that a wooden wrist rosary with a cross pendant measuring 2 centimeters had 42 percent lead, way above American safety standards that require pewter alloys to contain impurities of lead lower than 500 parts per million.