Is Pollution Linked to Liver Disease?

A new study suggests that environmental pollution may be associated with liver disease in the United States. The new data supports earlier evidence linking liver disease to highly exposed chemical workers.

The researchers analyzed data from the 2003-2004 National Health and Nutrition Examination Survey (NHANES). NHANES is a large nationally representative survey conducted by the National Center for Health Statistics, a part of the Centers for Disease Control and Prevention. The researchers examined the potential association between long-term, low-level exposure to 111 common pollutants (including lead, mercury, PCBs and pesticides) and unexplained liver disease in adults. The specific pollutants were detectable in at least 60 percent of the 4,500 study participants. Liver injury was indicated in people with elevated alanine transaminase (ALT) liver enzyme levels.

"Our study found that greater than one in three U.S. adults had liver disease, even after excluding those with traditional risk factors such as alcoholism and viral hepatitis," Matthew Cave, MD, assistant professor, department of medicine, division of gastroenterology and hepatology at the University of Louisville, said in a statement. "Our study shows that some of these cases may be attributable to environmental pollution, even after adjusting for obesity, which is another major risk factor for liver disease."

However, this study does not prove that environmental pollution causes liver disease. It only suggests that they may be associated with each other.

The researchers plan to study the potential additive effects of environmental pollutants on liver disease in children and adults with risk factors, including obesity, viral hepatitis and alcoholism.

The study was presented during Digestive Disease Week® 2009 (DDW®), an international gathering of physicians and researchers in the fields of gastroenterology, hepatology, endoscopy and gastrointestinal surgery.

For more information about environmental pollution, please visit Natural Standard's Environmental Resources database.

Comments

[Debbie Downer]

What? Did we think that there were benefits to pollution somehow? Of course there are going to be some ramifications if we are putting garbage everywhere in our environment. Our livers are responsible for detoxifying the harmful things we put in our bodies, so if our food sources are contaminated with pollutants, it shouldn’t be so surprising that our livers are being damaged.

[Demi]

I agree with Debbie. It makes sense that the liver would be affected since it filters harmful substances that enter our bodies. However, I agree with the author of this article -- this study doesn't prove that pollution actually causes liver damage. It just shows an association. I think more studies should look into this to see if pollution really does lead to liver injury.

[Chelsea]

It's pretty scary to think how pollution affects our bodies. I've heard that people in Los Angeles have many different types of chemicals in their blood because of all the smog and toxins that are in the air. I've also heard that pollution has been linked to respiratory diseases, including asthma. Thinking about all this makes me want to consider moving somewhere rural.

[Sue Yu]

Epidemiology studies have many potential risks for bias, and I agree with Debbie, the results of this study are not surprising; we all know that pollution is bad for us. However, I am confused by the quote from the researcher stating that “Our study found that greater than one in three U.S. adults had liver disease, even after excluding those with traditional risk factors such as alcoholism and viral hepatitis,” as this statement is not backed up by any statistics. One in three people do not have three times the upper level of normal for their liver enzymes. What is this man talking about?? Am I misunderstanding him?

[April Shauer]

Moving to a rural area may not necessary help you get away from pollution. As seen in a previous Natural Standard blog posting (http://blog.naturalstandard.com/natural_standard_blog/2009/05/state-of-the-air-report.html#comments), multiple rural areas in Maine, for example, received poor grades in terms of high-ozone days. Urban areas are not the only ones affected by pollution!

[samantha]

Sue, yes, I agree that it is fairly alarming to read that more than 1 in 3 US adults studied had liver disease, particularly given the very large sample size here. I would be interested in hearing how they define "liver disease" for these purposes.

I am currently doing some research on water purification, and to echo some other comments here, it is disturbing (but not surprising) to find these effects on the human body, given how many harmful substances from pesticides, chemical manufacturing, personal beauty products and more find their way into our water supplies.

[Heidi Clare]

I guess none of us can really escape from pollution, unless we start living in space. I would think with pollution being implicated in so many things, including liver disease, our society would try harder to prevent it, though. I wonder how many studies need to come out and how many health-related effects need to be found before we start actually trying to cut back our own pollution. I try to do my part, but I wish I had more resources about how I can learn to do more. Composting, recycling and car-pooling are all great, but there has to be more!

[Misty Waters]

Here’s a real quick question for those of us who take the MBTA, every day: how much pollution is stuck in THOSE tunnels? What toxins are stuck in the air? How many metal nanoparticles are floating in the air? Also, with the longer gaps in service now and extended waiting times in the tunnels, how much exposure do you get? I know I’m not the only one who sometimes feels the air is really thick and has a smell that chokes you up at the State & Downtown Crossing stations. Then the fans blow it directly into your face. How many former workers for the MBTA have rare diseases or cancers? Is that why the MBTA workers have pretty awesome health insurance? Has there been a study of any type or research done on this. Think about the babies/kids -- could this be more of the reason why asthma affects so many inner-city kids?

[Amiya]

Misty, you bring up some great points about the MBTA and the tunnel system that I have wondered about as well. The air in the various tunnels is heavily polluted and often blowing right at you. Pollution has a variety of negative effects on our bodies and the environment, and now, with this potential association with liver disease, something needs to be done, sooner rather than later, to create a cleaner and healthier environment.

[TB]

I agree with Heidi that none of us can really escape pollution. According to the U.S. Environmental Protection Agency, the biggest pollutant in Massachusetts is benzene (about 26.13%), which primarily comes from traffic emission. However, the air quality index in Massachusetts is rated “good” compared to other states in the U.S.

From my experiences, I have lived in Jakarta (it’s the capital city in Indonesia) for 18 years; I think the U.S. has done a good job promoting recycling either paper or garbage and keeping the traffic emission lower than other countries. I have enjoyed living in the U.S. and I breath better here. I can run every evening along Charles River without worrying too much about pollution. I hope that all individuals in the world will realize how important it is to take care our environment by using less paper, recycling, and preventing illegal logging.

[Barry]

It seems like one more negative health effect due to pollution. It is great to see so much research into the potential negative effects of pollution and how what we do affects our environment. But it would be nice to see more energy put into action to prevent these outcomes. I suppose raising awareness as has been done by articles like this one, will hopefully help to sway people to choose more environmentally friendly ways of living. One of the easiest is cycling instead of driving as a form of transportation. This not only eliminates emissions by not producing any, but at the same time, also helps reduce the risk of heart disease and diabetes.

[Tierra]

Awareness is key, and we have definitely come a long way in terms of promoting recycling and being more environmentally friendly in the past few years. We still have a lot do, but in comparison to some other places in the world, the U.S. is doing pretty good. I'm interested in seeing the results of the follow-up study assessing pollution + risk factors and liver disease, considering obesity is such a huge concern as well. I'd also like to see the incidence of liver disease related to pollution in other parts of the world, so we can assess this issue on a global basis.

[Alan]

I agree with Tierra that awareness is the key. I heard from someone that in other countries, if you go to a supermarket, they will charge you for a plastics bag if you didn't bring your own bag. This is very good because it enforces people to bring their own recycle bags and not to use the plastic bags that can harm the environment.

[Ricky]

Like any other organ, the liver is a very essential part of our body. It is constantly involved in performing different tasks, like manufacturing bile to help digest fats, regulating blood clotting, processing the body’s nutrients, and of course, breaking down toxic substances into harmless ones such that the body can either use it or discard it.

There are different ways the liver can be damaged or diseased. For instance, hepatitis A, B, and C are caused by viruses. Overdosing on drugs like Tylenol and alcohol may also damage the liver. As far as pollution and liver damage goes, more research will be needed before more definitive conclusions can be drawn.

[Sarah]

It is obvious that pollution is not good for our health. But even after reading this article, I am not fully convinced that pollution is linked to liver disease. More research is definitely needed. The terms “long-term” and “low-level exposure” also need to be defined for completeness and relevance of this finding. Also, since we can’t really escape pollution all together, what can we really do? Just simply avoid jobs with increased exposure to pollution?

[vitamine b6]

Study found that greater than one in three U.S. adults had liver disease, even after excluding those with traditional risk factors such as alcoholism and viral hepatitis.