In a survey of 31 countries, adult literacy largely stagnated or declined in the last decade, falling notably in the United States, the Organization for Economic Cooperation and Development found. And that, said Daphne Greenberg at Georgia State University, could have economic implications.

“The Coalition on Adult Basic Education, for example, cited that low rates of adult literacy actually can lead to a $1.4 trillion loss in gross domestic product,” said Greenberg, who is the director of the Adult Literacy Research Center at GSU.

Greenberg spoke with “Marketplace” host Kimberly Adams about what’s driving the decline and what’s being done to address the issue. The following is a transcript of their conversation.

Kimberly Adams: So a report came out recently that showed adult literacy in the U.S. is decreasing, but first of all, what actually counts as literacy?

Daphne Greenberg: That’s a very, very good question, because most people think of literacy as reading and sometimes they include writing, but we think of it as including a lot more. It includes numeracy, such as math. It includes adaptive problem solving, so that’s being able to use a computer and the internet and so forth to access information. But you know, there’s even a more general definition of literacy, and that is basically whatever an adult wants or needs in order to function to their full potential in the workplace, in society and in their family.

Adams: So how are we doing when it comes to literacy here in the United States compared with other countries, as well as how we did in the past?

Greenberg: Yeah, so unfortunately, we’re not doing as well as many people would think we are. About 28% of adults in the United States are reading at what’s considered Level 1 and below, which is really elementary skills. And we really do rank very lowly compared to other countries, but this isn’t a brand-new problem. We really have not focused enough on the skills of our adults in this country, and as a result, there are a lot of consequences, both for the individual and for society.

Adams: Most American kids, the vast majority, go to school and learn how to read. So how do we end up with adults who really struggle with literacy to the level that you’re talking about?

Greenberg: That’s a really good question. The adult education student is very diverse in the reason why they are at the point they are. So for some of them, it’s because they received very poor instruction. They just got passed along grade after grade after grade when they shouldn’t have been. For some of them, they were sick as children and missed a lot of school. For some of them, they moved around a lot. And as we know, different schools in different states and different neighborhoods are following different curricula. Some individuals have learning disabilities. Some individuals are immigrants to our country and so they’re learning to read and write in a new language. It really is a very complicated issue in terms of the reasons why.

Adams: There can obviously be a lot of shame attached to this, and people who struggle with reading or literacy may have developed some skills to hide it. What does it look like when somebody has low literacy, particularly in the workplace?

Greenberg: So, for instance, many, many, years ago, I tutored a woman who was struggling with reading, and she always came to my tutorial session on time. And I asked her, how did she do that? And she said, well, she used to watch “The Cosby Show” in those years. And she told me, “I know that during the second commercial of ‘The Cosby Show,’ I have to get out of my house and take the bus and walk to the bus stop to get to you on time.” And so they develop unbelievable compensatory skills. As another example, you mentioned the workplace. I used to know a person at a dry cleaners who had difficulty with people’s names and so forth, and he just literally memorized faces that went along with clothes. So they definitely, definitely do develop a lot of compensatory skills. And you’re right, there is a lot of shame associated with low literacy in our country, because there’s an assumption, which is incorrect, that every adult can can read very well and is proficient.

Adams: What’s the broader economic impact of the fact that there are so many folks in this country who struggle to read?

Greenberg: It has a lot of impact on both society and for the individual. So in terms of our economy, the Coalition on Adult Basic Education, for example, cited that low rates of adult literacy actually can lead to a $1.4 trillion loss in gross domestic product. ProLiteracy cites that there’s $100 billion to $200 billion loss in terms of health care costs. Because you can imagine that if you have difficulty reading you and using the internet — and so much of health care now is on the portals — that you have difficulties accessing health care. You have difficulties reading medical instructions, and that leads to poor health outcomes. There’s also the intergenerational transfer of literacy that can happen, because if parents have difficulty reading, then many of them are ashamed to read to their children and they can’t help them with homework.

Adams: And what sorts of strategies actually work to fix this issue?

Greenberg: Yeah, so there are adult education programs, and it really helps their self-esteem, first of all, because they realize, “Wow, I’m not the only one. And if I come and I attend, I will be able to really increase my skills, and I’m with a whole bunch of people who really care about me.” One of the problems, though, is that these programs now only access about 10% of adults who really need these programs. And part of the problem is there aren’t enough programs. Some people don’t know how to access them. A lot of people don’t even know that they exist.