How nano silver turns people blue

Ingesting silver — in antimicrobial health tonics or for extensive medical treatments involving silver — can cause argyria, condition in which the skin turns grayish-blue. Brown researchers have discovered how that happens. The process is similar to developing black-and-white photographs, and it's not just the silver.

Ingesting silver — in antimicrobial health tonics or for extensive medical treatments involving silver — can cause argyria, a condition in which the skin turns grayish-blue.“It’s the first conceptual model giving the whole picture of how one develops this condition,” said Robert Hurt, professor of engineering at Brown and part of the research team. “What’s interesting here is that the particles someone ingests aren’t the particles that ultimately cause the disorder.”

Scientists have known for years argyria had something to do with silver. The condition has been documented in people who (ill advisedly) drink antimicrobial health tonics containing silver nanoparticles and in people who have had extensive medical treatments involving silver. Tissue samples from patients showed silver particles actually lodged deep in the skin, but it wasn’t clear how they got there.

As it turns out, argyria is caused by a complex series of chemical reactions, Hurt said. His paper on the subject, authored with Brown colleagues Jingyu Liu, Zhongying Wang, Frances Liu, and Agnes Kane, is published in the journal ACS Nano.

Hurt and his team show that nanosilver is broken down in the stomach, absorbed into the bloodstream as a salt and finally deposited in the skin, where exposure to light turns the salt back into elemental silver and creates the telltale bluish hue. That final stage, oddly, involves the same photochemical reaction used to develop black-and-white photographs.