They tested cells from healthy people of various ages and also from children with Hutchinson-Guilford progeria, a rare hereditary disorder that resembles an accelerated form of aging.
The five grades of clean ore they tested ranged from 2to7percentent, with only one category falling below the E.P.A.'s regulatory threshold of 1percentt.
They tested MSCs from the teeth of six young people and six middle-aged and elderly folks, none of whom had Werner syndrome.
And eggs could easily become even more contaminated: Those they tested came from chickens living on soil that maxed out at about 600 ppm of lead, but levels greater than 1000 ppm are common in some cities.
They tested people from Romania, as well as Roma people.
At each location they tested 100 notes from a local bank and found that levels of cocaine contamination did not vary around the country.
They tested tumor DNA from 26 of the 45 patients for four genes that, when methylated, predict that a lung tumor will soon grow back after surgery.
The scientists saw a similar picture when they tested blood samples from people who had been immunized with the 2014 to 2015 vaccine.
Next they tested mitochondrial DNA from Dolly and nine other cloned sheep and found that "in all of them the mitochondria came just from one source," says Schon--the recipient egg.
That's what one couple in Utah -- named Paula and Jeff -- found recently when they tested their DNA from their artificial insemination in 1992.
