facts

Mercury in tuna

March 25, 2024 By EarthWise Leave a Comment

Mercury is found throughout the ocean, and there is at least some of it in any fish one might eat. It is an element found naturally in the environment, but it is also a byproduct of manmade pollution. Generally speaking, bigger fish tend to have higher mercury levels than smaller ones, because they are higher up in the food chain. The more small fish those big fish eat, the more mercury builds up in their bodies. Tuna aren’t the biggest fish in the ocean, but they are very common in many people’s diets.

Increased mercury levels are a result of human activities like burning coal and mining which release methylmercury into the air. It then finds its way into the oceans in rainwater. Methylmercury is a particularly toxic chemical that affects the nervous system. Environmental protection policies in recent decades have helped to reduce mercury pollution.

However, a recent study by French researchers looked at the mercury levels in tuna over the past 50 years. They found that the levels have basically not changed since 1971. As a result, they are calling for more restrictive environmental policies to further lower mercury pollution levels.

The researchers explained that the lowering of mercury airborne levels to date has not necessarily been ineffective. They theorized that the static levels in tuna may be caused by the upward mixing of “legacy” mercury from deeper ocean water into the shallower depths where tropical tuna swim and feed. It could very well take decades to dramatically reduce ocean mercury levels.

Meanwhile, mercury content in tuna varies considerably by tuna type and source and there are both better and worse choices out there. Consumers should learn the facts.

**********

Web Links

Mercury levels in tuna remain nearly unchanged since 1971, study says

Photo, posted November 7, 2015, courtesy of Mussi Katz via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

New Nutrition Labels

February 26, 2019 By EarthWise 1 Comment

Food and beverage packaging in this country has included a Nutrition Facts panel for nearly 25 years. Over 700,000 products have the labels which provide consumers with information like serving sizes, calories per serving, ingredients, and nutritional content.

Surveys indicate that 77 percent of all U.S. adults claim to use the labels at least some of the time. Whether the labels are actually useful is somewhat debatable. A couple of years ago, the FDA released a proposal to update the labels to make them more useful and to reflect more recent nutritional research. The new labels are finally going to be implemented and food manufacturers with annual sales exceeding $10 million have until January of 2020 to update their packaging with the new labels.

One of the biggest changes is that the “serving size” section of the label will be changed to more accurately reflect the actual portions consumed by the typical American. For example, a 20-ounce soft drink will now be labeled as a single serving because most people will drink the whole bottle in one sitting.

The new labels will no long list the amounts of Vitamin A and C, because recent research shows most Americans are not deficient in these nutrients. Instead, the amount of Vitamin D and potassium will be listed, two nutrients lacking in many diets. New labels will also show amounts of “added sugars”, defined as caloric sweeteners with no nutritional value. The new labels will also display the calories per serving in much large type making that piece of information far more noticeable.

There is surely more to be done to make food labeling more transparent and useful for consumers, but the new changes at least seem to be in the right direction.

**********

Web Links

Nutrition Labels Get a Makeover: Will It Make a Difference?

Photo, posted September 9, 2014, courtesy of Mike Mozart via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Science And False Beliefs

January 21, 2019 By EarthWise Leave a Comment

There are sizeable numbers of people who hold to beliefs that run counter to overwhelming contrary evidence. Flat Earthers and Holocaust deniers are well-known examples and, more recently, people – some of them in high places – who reject the evidence for climate change.

New research published in the journal Open Mind by developmental psychologists at UC Berkeley suggest that feedback, rather than hard evidence, boosts people’s sense of certainty when learning new things or trying to tell right from wrong. People’s beliefs are more likely to be reinforced by the positive or negative reactions they are exposed to than by logic, reasoning, and scientific data.

People’s learning habits can limit one’s intellectual horizons. According to the study, if you think you know a lot about something, even though you don’t, you’re less likely to be curious enough to explore the topic further and will fail to learn how little you know.

This phenomenon plays out in social media and cable-news echo chambers and explains how some people are easily duped by charlatans. Receiving positive feedback for what they are saying can make people believe they know more than they actually do. This confidence makes them less likely to seek out and learn more information about the subject, as well as take into account contradicting opinions or facts.

Another factor is that what influences people’s certainty is that their confidence tends to depend on what they heard most recently rather than on long-term cumulative data. A few pieces of recent information tend to get much more attention than an extensive body of data. If a crazy theory is able to make a correct prediction a few times, people tend to get fixed in their belief in that theory and be less open to other information.

**********

Web Links

Here’s Why People Advocate False Beliefs, Conspiracy Theories Despite Evidence

Photo, posted February 2, 2007, courtesy of Tim J. Keegan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

CO2 Emissions Stalled

December 13, 2017 By EarthWise Leave a Comment

For the third year in a row, global emissions of carbon dioxide have remained unchanged. This indicates that efforts to reduce emissions have had an effect, but that there is much more to be done. It is essential to reduce emissions, not just cap them.