A popular brand of butter is disappearing off the shelves temporarily because of something called forever chemicals Plus. Our tests found concerning levels of cadmium or lead to toxic heavy metals in most of the dark chocolate bars we tested. Consumer Reports found heavy metals and a lot of dark chocolate brands find out how much you'd have to eat to really be at risk for health problems. And these two bottles of ketchup from the US and the UK seem almost identical. But wait until you see the difference in their ingredients. Today, we're chewing on what's really in your food. Let's dig into it. When we go to the grocery store, we're used to checking all kinds of labels, from that expiration date to the calorie count. Also, yeah, now some doctors want you to look for another label, one that says no PFAS. Dina Dimitrius digs into why it could be important to your health. It's as natural as the day my great grandfather made the butter. Irish kerrygold butter is prized by many consumers for its grass fed goodness. But what consumers may not have realized that grease resistant wrapper contains per or polyfluoroalkyl carbons PFAS for short, a toxic artificial compound they lost forever. They're called the forever chemicals because they're very persistent. University of Notre Dame biochemist Graham Peasley coauthored studies on PFAS. His team uses a special particle. Accelerator to test fluorine levels in products. They are used in over 1600 different industrial processes and products. They make Teflon pans non sticky, they make clothing waterproof, they make packaging waterproof. In late 2022 carry gold stopped restocking its foil wrapped butter to retool its packaging for California and New York ahead of new State PFAS laws. The company provided a statement that reads in part. We will continue to ensure packaging for our products remains compliant with all relevant. State legislation and regulatory requirements carry gold's butter wrapping is not linked to bad health outcomes, but pifa's in general have been linked to certain cancers and other health dangers like high cholesterol and preeclampsia and those who are pregnant. We've since discovered that all these PFAS are immune suppressants, so they suppress your immune system. And that means any opportunistic disease, including some types of cancer, could take over 11. States now have rules either banning or reducing PFAS levels and items ranging from carpets clothing. In cosmetics to food wrappers and containers, many companies have voluntarily removed intentionally added pipas from their products or packaging. The site PIFA central by scientists at the Green Policy Institute, lists dozens of companies with PFAS free products, including clean at Sephora, IKEA, H&M and Chick-fil-A Food Packaging. The big companies have pledged to phase out by 2025, and the smaller companies are already doing it. Peasley says they're hard to come by, but consumers should start looking. The labels that say no PFAS. Dina Dimitrius, CBS News Los Angeles. While you're looking at stuff on the products, ketchup is a favorite around the world. Look at these two bottles, they seem pretty similar. You got the one from the UK over here and the US one over here. Just some differences in the packaging, but wait until you see what's also different with their ingredient list. Check out the differences here. So for the UK bottle of Heinz ketchup, there are about six ingredients, all recognizable, but that's not the same for the classic US1. Take a look at how much longer this thing is. There are three. Added ingredients in the US version. See this right here. High fructose corn syrup, corn syrup and natural flavoring. Those ingredients have raised some controversy in the past few years. For example, the environmental Working Group says natural flavoring. Natural. It's not actually that. It's pretty deceiving. To be clear, they're not saying the ketchup is bad for you, but they say it's an example of not always knowing what you're getting. According to EWG, they say natural flavoring. Can contain mixtures of more than 100 chemicals. Heinz does not list exactly what natural flavorings are, they just say it's a mix of spices. Now, today, there are more than 10,000 chemicals and additives allowed in food in the United States, often in small amounts, but they haven't evaluated all of them at the FDA in decades. Doctors say the majority are safe, but some chemicals allowed here have been banned overseas after being linked to cancer. And developmental or behavioral issues? We need to put the F back into the Food and Drug Administration. She's a congresswoman from Chicago who introduced a bill requiring the FDA to review certain chemicals banned overseas. If it passes, it would close what's known as the GRAS loophole, chemicals generally recognized as safe. She says this allows companies to skip an extensive safety review when adding many chemicals to food. Well, the congresswoman. Says we are far behind other countries in food regulations right now. In California, there's a proposed legislation that would ban 5 common chemicals from all foods that are sold. California would be the first state to do this, and that could then trickle down to other places. It's not just chemicals though, there are also heavy metals to watch out for. A new Consumer Reports investigation reveals a dark side to some of your favorite dark chocolate. Our tests found concerning levels of cadmium or lead to toxic heavy metals in most of the dark chocolate bars we tested. Consumer Reports tested 28 dark chocolate bars and the results? For 23 of the bars, eating just an ounce a day would put an adult over a level that Crohn's experts and public health authorities say may be harmful. Long term exposure to heavy metals can cause kidney damage, hypertensive hypertension, and reproductive issues. Don't just assume that organic is better. CR tests found that organic dark chocolate was just as likely to have concerning levels of heavy metals as other products. OK, growing up we were always told chocolate wasn't the healthiest option anyway, but fish is supposed to be one of the best things you can eat. Except doctors say some kinds could have high levels of mercury that could cause some problems. Possible health risks from mercury include impaired brain function, loss of smell and developmental delays in children. If you have a high mercury level while the brain is developing in a fetus, there can be cognitive issues later in life. So we're very cautious in a developing brain. So that is. Young children and pregnant women especially need to keep mercury away from those neurons that are developing, CBS News Medical contributor Doctor David Agus says. Certain fish have more mercury. It's the larger fish and the deeper fish where you get the mercury. Swordfish, tuna and other big deep fish have higher levels of mercury, very little mercury, for example, in salmon and trout and other smaller fish that are at the surface. So for typical adults, it's best to not eat those fish too often. You can have one to three servings a week of tuna and as an adult it would be very safe, the doctor says. As always, moderation is key. Of course, trying to consume safe and healthy foods can sometimes feel overwhelming. The bottom line is we learn more everyday about what we put into our bodies, and the more you know, the more you can protect yourself.