How toxic is the Tijuana River? San Diego high-school students are helping scientists find out.

The most wide-ranging survey of industrial chemicals in the Tijuana River Valley was published in a study last month, scientists say, and some of the hands behind the work were those of high school students who may never have considered science a calling.

A team of scientists from UC San Diego and the Boz Institute, a nonprofit that promotes life science education, involved students from the San Diego region in a new sampling method they say provides a deeper look into the environmental impacts on the wetlands. By bringing students into the fold, the researchers believe hands-on education in matters that concern their community creates a more holistic approach to science education.

“What you see is this incredible ecosystem where kids are engaged in cutting edge research that is tangible, but in a way that also helps them serve their community,” said Morgan Appel, an assistant dean at UC San Diego Division of Extended Studies.

The age diversity of the team came at no expense to the science, he added, and the findings are opening new threads of research that could bring some answers about long-term exposure to Tijuana River pollution.

Some of the chemicals they found embedded in Tijuana River Valley sediment date back decades.

Now the scientists say they are looking at how the chemicals work their way up the food chain, and how they may impact the environment and public health over long-term exposure, even at levels that comply with may federal water quality standards.

“Oftentimes, we make our regulatory decisions based on … data that is convincing, but it doesn’t really represent chronic, prolonged, long-term exposure type scenarios,” said Goran Bozinovic, the CEO of Boz Institute.

Also a UCSD biology lecturer, Bozinovic said that while much focus in the estuary has been on wastewater, which is mostly made up of organic material, their study was designed to fill a knowledge gap in terms of industrial waste impacts.

Instead of collecting individual samples, the scientists used instruments that sample water at various locations over a period of several weeks at time. The method allows them to understand how chemicals move throughout the channels of the estuary, as well as test for a much wider range of chemicals.

They identified 169 chemicals including petroleum based substances, plasticizers, pharmaceuticals, as well as pesticides, some of which have been banned for decades. Sediment in the estuary accumulates the chemicals, many of which stay intact for long periods of time.

The Centers for Disease Control and Prevention categorizes many of the chemicals as carcinogenic and says long-term exposure at low levels to the substances is unknown.

Bozinovic says they are now testing how the chemicals affect living organisms. One of the approaches they will use is to apply extracts of the chemical to liver tissue in a lab in order to study long-term impacts on human health and assess risks.

Bozinovic and Appel say their collaboration, which is also supported in part by the California Coastal Commission, is focused on producing critical science while modeling a path toward solutions to the pollution crisis.

“The first thing that students learn is that the water doesn’t really understand the flags and boundaries and borders,” Bozinovic said. Students learn that they, “can’t think locally and try to solve these problems.”

Almost 60 students from 35 high schools and two community colleges participated in the study including some from Sweetwater High School in the South Bay.

Claire Wang, a junior at Del Norte High School in Poway who participated in the research, studied how fish embryos reacted to various concentrations of polluted water. She said it stunted their growth and deformed others.

She hadn’t had many opportunities to visit the communities near the Tijuana River. Getting involved in the project opened her eyes to the severity of the pollution crisis. She said it also should help convince others to do something to address it.

“Once you see how bad the problem is, I think they will be more inspired to help make a change.”