By Tom Costello
NBC News

WASHINGTON (NBC) -- Consumer Reports magazine reveals it's latest research into arsenic levels in apple and grape juice -- may cause some parents to think twice before pouring a glass.  

Of the eighty-eight samples tested, by Consumer Reports, ten percent had total arsenic levels that exceeded federal drinking water standards.

Unlike water, there are no federal limits set for juice.

"I don't understand how there could possibly be such a thing in something so natural," says Valerie Spencer, a mother.

"If it's to the point where it's causing harm to her development, definitely I would stop," says Roberta Eiermann, mother.

This isn't the first time apple juice has been in the headlines. 

"I'm worried about it as a father of four," says Dr. Oz.

In September, Dr. Oz announced findings from his own study of arsenic levels in apple juice.

"Some of the best known brands in America have arsenic in their apple juice," says Dr. Oz.  

An independent lab, hired by "The Doctor Oz Show", found one third of the tested samples to have arsenic levels higher than what the EPA allows in drinking water.

The FDA took issue with Dr. Oz's findings saying the study didn't differentiate between the two types of arsenic - organic and inorganic.

Now, Consumer Reports says it does make the distinction, adding, "most of that arsenic (it found)  was inorganic arsenic, a known carcinogen."

In September, the FDA insisted apple juice is safe.

"Our testing found that lot of juice has such a small amount of arsenic in it that it would be no concern what so ever," says Don Zick, Senior Science Advisor for FDA Safety and Applied Nutrition.

The FDA still stands by that but in a statement to NBC News it now says it is conducting more tests "to help determine if a guidance level can be established that will reduce consumer's exposure to arsenic in apple juice."

Meanwhile, the juice products association, says it's committed to following federal guidelines as it has for decades.

Adding, comparing arsenic in apple juice to water is "not appropriate" and "regulatory agencies have set lower thresholds for drinking water than for food and other beverages because people consume larger amounts of water."

Meanwhile, Consumer Reports does not suggest erasing juice from your child's diet.

The American Academy of Pediatrics suggests diluting juice with water and limiting consumption: 4 to 6 ounces per day for children under six and no more than eight to twelve ounces for older children.