Researchers at the University of California San Francisco (UCSF) analyzed blood samples from newborns and pregnant women. The researchers found 55 chemicals previously undetected in people, according to a recently published study in the journal Environmental Science & Technology.

The research involved 30 San Francisco-area women and their babies.

The UCSF researchers used high-resolution mass spectrometry (HRMS) to identify the human-made chemicals in the blood samples.

Tracey Woodruff, PhD, study author and professor, OB-GYN, reproductive sciences, University of California San Francisco, said that the goal of the research was to find better ways to detect chemicals in the environment and people.

She said even though she is not surprised by the findings, she still considers them “disturbing.”

“Unfortunately, [we were] not surprised by the total number of chemicals as we’ve suspected they’ve been there. We’ve just struggled to identify them,” she said. “The number of mystery chemicals that we can’t identify sources or uses for is very disturbing.”

Dr. Kenneth Spaeth, division chief, occupational and environmental medicine, at Northwell Health in New York, said the list of chemicals is very long. He also said most of them are different variations on the same “molecular theme.”

“Meaning that, for example, phthalates or BPA, there’s a lot of chemicals for which there’s a lot of different versions of similar chemicals and they behave similarly.” He said. “Trying to keep track of all of them is really hard.”

According to the Centers for Disease Control and Prevention (CDC), phthalates are a group of chemicals used to make plastics more flexible and harder to break. BPA is used in items like drink containers, plastic dinnerware, and toys.

We get exposed to these substances by eating and drinking foods that come in contact with containers and products that contain the chemicals.

“Phthalates are certainly among the ones of concern. I mentioned BPA, but there’s a number of other categories,” said Spaeth. “There are pesticides used regularly in food agriculture that can function as endocrine disruptors.”

Many chemicals used in the packaging can migrate into food or the product itself, he said. Also, some chemicals are used in the personal product itself.

“These all become fair game for raising the risk,” he said. “Tracking them and figuring out where they’re coming from is problematic.”

The study may help doctors figure out where exposure is coming from.

Spaeth also explained why it is so difficult to avoid exposure.

“I think the key thing is that, even if one chooses to try to avoid exposure, it’s an extraordinarily difficult thing to do,” he said.

That is because of widespread chemical use and the high number of different chemicals in our environment. Also, consumers have little information about which products contain which chemicals.

”There’s almost no way for consumers to really try and maneuver their way through this if they’re seeking to try to avoid these chemicals,” he said.