Watch the CBSN Originals documentary, "Period. Half the population has one. But no one talks about it," in the video player above.

Half the world's population gets a period every month. And yet, even in America, there is such a stigma surrounding menstruation that the majority of girls and women still feel uncomfortable talking about it.

"We all have that story where we get our period at school or at work and we stick [a tampon] up our sleeve... and sort of like walk that walk of shame to the bathroom," said Congresswoman Grace Meng, D-New York, in the CBSN Originals documentary, "Period." "That's just something that we've grown up with, right? I've always thought that it was something embarrassing that I had to hide from my peers, and I think that it is something that our society in America needs to feel more comfortable talking about. It is a demonstration of how genders are treated inequitably."

In fact, that stigma — and the secrecy that it spawns — have given rise to a painful reality known as period poverty, which quietly affects millions of American women every day. In essence, period poverty means not being able to afford to purchase feminine hygiene products, like tampons and pads. And while many of us probably take access to these sorts of products for granted, there are growing populations of women and girls who have to make impossible life choices every month, just to survive their cycles.

"If you have to pick and choose, do I buy food for my child or do I get my sanitary needs, that's kind of hard and no one should have to experience that," said Brooklyn native Nicole Johnson, who went into a homeless shelter in 2005 with her four children. "It's demeaning. It makes you feel very sad. ... It's a heartbreaking situation."

Johnson now lives in transitional housing, but she is one of the more than 16 million American women — 1 in 8, according to 2016 U.S. Census data — battling poverty every day.

"If you can't even put a loaf of bread on the table, how do you expect a person to buy a box of tampons that may be $5 and change?" she explains. "Most people don't stop and think about it. I guess they feel they're able to get their own pads and tampons. It's the littlest things that people don't focus on. Yes, you need food, you need water. There's plenty of soup kitchens. But the personal items, the sanitary napkins, the soap, the toothpaste, deodorant… it's not that easy for people."

To make matters worse, women cannot buy tampons or pads with public benefits like food stamps. They are not included in flexible or health spending account allowances. And they are not covered by health insurance or Medicaid.

So the only financial assistance women can really hope for is in the form of taxes. After all, every state has the ability to pick and choose products they'd like to make more affordable by exempting them from sales tax. All 50 states have given tax exemptions to prescription medications, even optional male enhancement ones like Rogaine. Louisiana did it for Mardi Gras beads. Idaho did it for chainsaws. Illinois even did it for BBQ sunflower seeds. Yet, to date, only 15 states and Washington, D.C. have officially exempted pads and tampons from sales tax.

"It raises some questions about what kinds of parameters we're putting around how we define a necessity, and who's making that call," said Jennifer Weiss-Wolf, author of "Periods Gone Public." "There have been times and places where legislators have actually stood up and said, "Well, wait a second. This is only going to benefit women, so it's sexist… somehow missing the point that if only women are impacted by it, or paying it, is it not sexist?"

The activists of the booming menstrual movement certainly feel that is.

"You know, people will say that we're seeing how broken the systems are and it's time to fix them," said Weiss-Wolf. "I don't actually think of it that way. I think the systems are working exactly as they were intended to do, which was to keep women out of power. ... And ignoring menstruation is just as much of a part of that as all of these other arguments and cases that we're arguing now."

Celebrities like Busy Philipps, who regularly advocates for women's rights and the destigmatization of women's health issues, have now taken up the cause, as well, by bluntly and nonchalantly discussing their periods on both social media and national TV.

"Something that happens to half the population once a month shouldn't be a taboo subject," Philipps told CBS News. "I mean, to be totally honest, and I'm sure I'm not the first person to say this, but like if men had their periods, it would be like f***ing celebrated. You know, it would be like a holiday. They would get the week off of work and probably the week before and then like the four days after their period ends, so that they could recover. It would just be a different experience. But men do not get periods. Women get periods."

But as the country takes a hard look at the long hushed-up history of sexual harassment and assault, menstrual activists hope that the time may now be right for the public and its representatives in government to also take a fresh look at the truth about menstruation in America.

"I think that in the United States of America, the fact that there are women, whether they are girls in schools, women in prisons and homeless shelters, to women working in large companies... who aren't able to afford these products and as a result may miss school, may miss work, face certain stigma," said Congresswoman Meng, who put the Menstrual Equity for All Act before Congress in March. "I think it's a human rights issue that, especially in the United States of America, women should not have to be dealing with."