By Lisa Sigell

LOS ANGELES (CBS) — Arsenic is a dangerous poison that for decades has frightened people by its name alone, but now the substance is finding its way into popular foods.

Anna Fox is a mother of three from Van Nuys, who is careful about what she allows her kids to eat. She took away foods with artificial dyes and saw a huge difference in her son’s behavior.

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“We just have study after study. Apple juice and arsenic, how much is too much,” Fox said.

Now she is surprised to find out that high levels of arsenic are turning up in some juices, cereal and energy bars, toddler formula and more.

“Avoid this, avoid that. Even organic food is coming up with arsenic in it and it’s really frightening,” she said.

Organic arsenic is around us all the time, located in the ground and in the water, but inorganic arsenic — a byproduct of industry, pesticides and more — seeps into the soil and into our food. Crops like rice tend to absorb more arsenic.

About two thirds of U.S. apple juice concentrate now comes from China, a country that is widely known to use arsenic-based pesticides in farming.

“We know at toxic levels it’s linked to abdominal pain, vomiting, diarrhea, skin irritations, immune system problems and even cancers. And as a parent and a pediatrician, that makes me concerned,” said Dr. Jeremy Shapiro of Providence Tarzana Medical Center.

Recently several major studies have put the spotlight on arsenic.

Dartmouth University highlighted foods that use organic brown rice syrup or other rice ingredients, as having higher levels of arsenic than what the EPA allows in drinking water.

That included one toddler formula with levels of arsenic up to six times high than the EPA allows.

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Another study detected trace amounts of arsenic in chicken.

A third study by Consumer Reports found levels of arsenic in some juices again exceeded what is allowed in drinking water.

But if the EPA has set limits on how much arsenic should be in our drinking water, why has it not done the same with our food?

Congressman Frank Pallone Jr. (D-N.J.) has introduced what is being called the Apple Juice Act of 2012, requiring the FDA to establish standards for arsenic and lead in fruit juices.

But he wants to go even further with limits for all foods.

“Most people think when they go into a supermarket or grocery story, they buy something that is going to be consumed by their kids, that someone has made a decision to review this and make sure it is safe and it’s not necessarily true. And it bothers me that they operate under sort of false assumptions. And they shouldn’t have to worry that it’s not safe,” Pallone said.

But the FDA disagrees, saying from juices to cereal bars, the products are safe.

“Because arsenic is naturally occurring in the soil and is naturally used in pesticides, we are aware that there are trace amounts in many foods,” the FDA said in a statement.

Despite that, they have launched a large-scale study on arsenic levels in rice.

“What I don’t want is for anyone to panic just yet. What we need to do is just get more information, more research and once we do, then we’ll be able to make better decisions for you, for me and for our children,” Dr. Shapiro said.

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As for Fox, she is not buying into the “everything is safe” thinking. Until more studies are done, she is limiting what her kids eat and drink.