Environmental experts are warning consumers that lead is a key ingredient in the plastic needles and light cords of artificial Christmas trees.

84 year old Carolyn Wynn bought a new tree her last year at her local Kroger store.

"We were so thrilled with it because I didn't have to put 500 strings of lights on it,” said Wynn.

Only after taking it down after New Year’s Day did she notice the tag. “That little tiny thing way back in the tree. I didn't even know it was on there when I put it up,” she says.

Wynn had found a label mandated by the state of California. It warned her new tree contained lead.

“A toxic element linked to cancer and birth defects,” the tag warned.

We went to five major retailers, shopping for artificial trees, garland, a wreath and Christmas lights.Every product we saw came from China, and nearly all had a posted warning about lead.

“We found that if we leave one of these trees standing for a week, and we wipe under the tree we’ll find large amounts of lead dust in many cases under the tree,” said Dr. Richard Maas of the University of North Carolina at Asheville.

Maas and his staff have tested more than 200 trees. After checking decorations we provided, Maas said they found the most lead in a light cord from Target.

The state of California requires a warning on anything item containing more than half a microgram of lead. The cord had 22 micrograms.

“That's a significant lead exposure, especially for a young child who would tend to put his hands in his mouth afterwards,” said Maas. Maas recommends discarding a tree that measures six micrograms or higher. The tree from Kroger measured nearly five micrograms.

“It would still in many usage scenarios expose a young child to enough lead to knock a couple of IQ points off that child's intellectual ability," Maas said.

Researchers say 50 million artificial trees are in U.S. homes, and of those, 20 million are nine years old or older. Maas says the older the tree, the more lead it will likely give off.

A tree from Wal-mart, a garland from Lowes and a wreath from Home Depot, each had minimal amounts of lead. Most of the light cords included with those decorations had much high readings.

Maas says each item taken individually poses only a slight risk, but he warns lead exposure adds up.