Health care advocates worry that more than 100,000 Californians who are eligible to purchase affordable insurance through the Health Benefit Exchange will not enroll because of language barriers, according to a study released last week by the Oakland-based nonprofit, California Pan-Ethnic Health Network.

The study, by researchers at UC Berkeley and UCLA, estimates the likely enrollment in health care reform programs in the state, including the Health Benefit Exchange—a health insurance marketplace that launches nationwide on Jan. 1, 2014, as part of the implementation of the Affordable Care Act.

The study’s lead researcher, Daphna Gans, a research scientist at UCLA’s Center for Health Policy Research, said the study predicts that people who speak English “less than well are going to be disadvantaged” when the exchange program becomes operative.

The study found that of the more than 2.6 million non-elderly adult Californians eligible to receive federal tax credits to buy insurance in the exchange, more than two-thirds, or approximately 1.73 million, will be people of color.

Only 42 percent of those eligible for tax credits, that is, those whose income is between 133 percent and 400 percent of the federal poverty level—are projected to enroll because of limited English proficiency, unless proactive outreach efforts are carried out, according to the study. If language were not a barrier, the study predicted 53 percent of the 1.06 million people with low English proficiency would enroll by 2019.

Of the population eligible for tax credits on exchange, 48 percent will be Latinos, 2 percent Native Americans, 4 percent African Americans, 32 percent whites and 14 percent Asian American and Pacific Islanders, according to the study.

“Our success in implementing this new program will be measured not just by the number of people enrolled, but by the state’s ability to reach those who are most often left behind,” said Ellen Wu, executive director of CPEHN, which financed part of the study.

She added: “We have to target resources through multicultural and multilingual outreach to ensure that communities of color who are eligible, particularly people who speak English less than very well, enroll in coverage.”

The exchanges, which could be operated by either the state government or the federal government, will serve as online hubs for individuals and small businesses to compare and purchase health insurance plans. Low and middle-income Americans will be able to use new tax subsidies to purchase insurance through the exchanges.

In California, more than 15 million residents speak a language other than English at home, and nearly half of them have limited proficiency in English.

“These are difficult times for California families, and ensuring every Californian has access to quality, affordable healthcare is vital for our economic recovery,” said Assembly Speaker John Pérez, who authored legislation in 2010 establishing the exchange. “The Health Benefit Exchange will help lower the cost of health insurance for every Californian, but it’s vital for every eligible Californian to enroll to ensure we bring healthcare costs down as much as possible for California’s working families.”

The responsibility to counter this lies with providers, counties, and the state working together and reaching out to the communities, Wu said.

Peter Lee, executive director of California’s exchange, said the study only affirms that steps need to be taken to reach out to communities that speak different languages and come from diverse cultural backgrounds.

But “that’s been inherent in all our planning,” he said.

California has contracted with a marketing firm to develop an outreach plan to show how best it can work with community-level and faith-based organizations, as well as the ethnic media to put the word out about the importance of enrolling in the Exchange, Lee said.

When the state applies for a federal grant “for Level 2” implementation of the exchange in June, it will ask for funding for outreach, he said.