Air pollution has become a global burden in the 21st century.
Not only does it affect the atmosphere but also harms your health and well-being.
Did you know that 92% of the global population live in places with poor air quality?
That could be you!
While most people are worried about how air pollution might affect their lungs and heart but here are a few startling studies that show that pollutants damage the liver as well.
Read more to find out about the harmful effects of pollutants on the human liver.
What is Air Pollution?
Air pollution occurs when high amounts of deadly gases, organic compounds, and particles collect in the air.
Both human actions and natural events can give rise to possible pollutants. Some of these include gases, such as ozone, carbon dioxide, sulphur and nitrogen oxides, as well as organic compounds like methane.
Fine particles created by the burning of coal or during forest fires also act as pollutants.
The liver can be damaged in many ways which will affect the metabolism.
A common problem is liver fibrosis which starts the scarring of liver tissue. At the last stage of scarring, liver cirrhosis will occur which causes loss of the liver cells.
The non-alcoholic fatty liver disease occurs when fat deposits in the liver of people who do not drink alcohol.
Cirrhosis can often lead to tumour formation causing cancer.
All of these factors gradually reduce liver function.
How does Air Pollution affect the Liver?
This article explores how the liver is damaged by chronic exposure to air pollution.
Several reports have acknowledged the relationship between exposure to the pollutants and liver-related problems.
Long-term contact with pollutants like particulate matter can cause fibrosis in the liver. Excessive fibrosis will inevitably lead to cirrhosis. Long-term exposure to particulate matter can activate immune cells in the liver causing inflammation and bringing about the non-alcoholic fatty liver disease. The risk of liver cancer is also increased in polluted areas as pollutants cause inflammation and cirrhosis. Particulate matter air pollution affects the liver tissue and reduces liver function.
1. Air Pollution Can Cause Liver Fibrosis
Liver fibrosis occurs when certain proteins, such as collagen, deposit in high amounts in the hepatic (liver) tissue.
Fibrosis helps to build up connective tissue to speed up wound healing but an excess of it affects the functioning of the liver.
This condition is commonly seen in most types of chronic liver disorders and can lead to liver failure.
Food habits and lifestyle act as risk factors for undue fibrosis but, recently, studies have also implicated air pollutants as agents of liver damage.
How does air pollution cause liver fibrosis?
In 2010, researchers at the University of Copenhagen studied an animal model of liver disease and found that air pollutants like those found in wood smoke can cause oxidative damage and increase liver fibrosis.
A 2014 review by the Chonbuk National University evaluated the role of air pollutants, such as particulate matter (PM) and carbon black, in causing liver disease.
The results showed that exposure to these chemicals actually speeds up liver fibrosis, which can progressively degrade the condition of the liver.
This review was based on a 2006 animal study done by researchers at the Shanxi University.
As per the results, it was seen that air pollutants would travel from the lungs to the liver and have a toxic effect on the liver tissue by causing inflammation.
Pollutants found in wood smoke, such as particulate matter and carbon black, often cause inflammation and oxidative damage in the liver tissue. Thus, air pollution increases the risk of fibrosis.
2. Air Pollution Increases the Risk of Cirrhosis
Cirrhosis refers to a medical condition where the liver fails to function properly because of long-term tissue damage.
This damage is usually marked by the substitution of normal liver tissue by scar tissue, which was formed as a result of wound healing. The disease typically develops slowly over months or even, years.
Cirrhosis is most commonly caused due to long-term alcohol abuse, prior hepatitis (B or C) viral infections, and even non-alcoholic fatty liver disease.
How does air pollution cause cirrhosis?
In a 2014 study published in the journal, Toxicology Research, the researchers investigated the role of air pollutants in bringing about liver disease.
It was found that pollutants like fine particulate matter can horribly scar the liver resulting in cirrhosis.
The primary reason behind air pollution causing cirrhosis is the onset of liver fibrosis.
As already mentioned, fibrosis is the first stage of liver disease. When the scarring is adequate and liver function has deteriorated by a large extent, cirrhosis occurs.
Pollutants, such as ozone and particulate matter, cause oxidative damage of the liver which speeds up fibrosis to such an extent that cirrhosis is inevitable.
This is because new connective tissue keeps depositing on the cells of the liver to lessen the damage caused by inflammation.
However, this continues to such a high degree that the formation of scar tissue causes a complete loss of liver function.
The major reason behind pollution-related cirrhosis is the development of excessive fibrosis in the liver tissue. Particulate matter is responsible for the high degree of scarring in the liver.
3. Air Pollution Exacerbates Non-Alcoholic Fatty Liver Disease (NAFLD)
Non-alcoholic fatty liver disease (NAFLD) is actually a type of liver disorder that occurs when excess fat gets deposited in the liver tissue even when the individual does not regularly consume high amounts of alcohol.
The non-alcoholic fatty liver disease is quite predominant in developed nations.
NAFLD results in improper functioning of the liver. It is usually accompanied by type 2 diabetes mellitus, metabolic disorders, and obesity.
How does air pollution exacerbate NAFLD?
A 2013 review by the Francesco Balsano Foundation examined the role of environmental pollution in causing non-alcoholic fatty liver disease.
They found that exposure to pollutants like ozone and particulate matter causes inflammation in the liver which is one the major precursors for NFALD.
In an experimental study conducted by the Wayne State University School of Medicine, it was found that pollutants like very fine particulate matter cause a metabolic disorder.
Mice that were on high-fat diets suffered from metabolic disorders when exposed to significant amounts of air pollutants, which ultimately led to NFALD.
A study by the Mount Sinai School of Medicine also implicated the role of air pollutants in causing NFALD.
The results of this study that long-term exposure to air pollutants activate specific immune cells in the liver, known as Kupffer cells.
This results in inflammation and can bring about the development of fatty liver.
Very fine particulate matter cause inflammation in the liver, which can affect the metabolism if the individual is on a high-fed diet. This is followed by the activation of special immune cells in the liver, which can lead to NAFLD.
4. Air Pollution Increases Liver Cancer Risk
Liver cancer, also referred to as hepatic cancer, is cancer that begins in the liver.
However, cancer which has spread from somewhere else and comes to the liver is more common than that which begins in the liver.
Symptoms of this fatal disease may include a lump or ache in the right side under the rib cage, bulging of the abdomen, jaundiced skin, easy bruising, loss of weight, and extreme weakness.
The major causes of liver cancer are cirrhosis, hepatitis B or C infections, and alcohol abuse.
Recently, air pollution has also been established as a major risk factor for the development of cancer.
How does air pollution increase liver cancer risk?
A recent study by the University of Texas Medical Branch evaluated the role of hazardous air pollutants and the incidence of liver cancer in the city of Texas.
It was found that there are many toxic pollutants which act as carcinogens and alarmingly increase the risk of cancer in people living in the city.
Another 2017 study conducted by the University of Southern California examined the relationship between particulate matter air pollution and liver cancer risk.
The finding showed that not only does long-term exposure to such pollutants cause inflammation in the liver that can bring about cancer, it can also increase cancer deaths by speeding up the process.
A collaborative European study also inspected the relationship between liver cancer and the incidence of air pollution.
It was seen that severely polluted areas were associated with higher cases of cancer primarily because this breathing in of these pollutants can initiate tumours and the formation of malignant (cancerous) cells in the liver.
Another major reason behind the increase in cancer risk is because air pollutants cause liver cirrhosis, which is frequently associated with the development of malignancies.
This was proved by an old study in Italy, where it was seen 17% of primary liver cancers were brought about by cirrhosis.
Air pollution greatly increases the risk of liver cancer primarily because it causes inflammation in the liver and can initiate tumour formation. Cirrhosis caused by pollutants is also another reason behind the increased risk of liver cancer.
5. Air Pollution Reduces Liver Function
The liver has numerous functions.
It makes several of the chemicals required by the body to function properly; breakdowns and purifies substances in the body; and also acts as a storage unit for substances.
Hepatocytes (liver cells) are in charge of producing many of the proteins in the body that are necessary for several bodily functions, including blood clotting factors.
The liver plays a significant role in detoxifying the body by changing ammonia, a derivative of metabolic reactions in the body, into urea that is removed in the urine by the kidneys.
How does air pollution reduce liver function?
In 2008, researchers at the Chinese Center for Disease Control and Prevention conducted an animal study to understand the impact of particulate matter pollution.
It was found that these fine particles activate immune cells in the liver, which release chemical messengers that bring about inflammation.
As a result, the liver tissue is affected and functioning is reduced.
A 2013 study carried out in Munich, Germany, studied the impact of air pollution on liver enzymes.
The results showed that pollutants, such as fine particulates and nitrogen dioxide, alter the activity of the major liver enzymes, which have a role in the metabolism.
As a result, the liver function is affected.
A 2016 study undertaken by researchers at the Mashhad University of Medical Sciences assessed the impact of air pollution on human health, particularly the liver.
It was established that chronic exposure to gases like ozone alters the integrity and functioning of the liver tissue.
The normal, healthy hepatic cells get replaced by abnormal scar tissue, which reduces liver function.
Pollutants, such as ozone and particulate matter, cause inflammation in the liver; change the integrity of the liver tissue; affect the activity of liver enzymes, all of which reduces the liver function.
To summarize, it can be said that air pollution causes widespread damage to the liver.
These lead to the development of a whole range of liver disorders.
The most common outcome of long-term exposure to air pollution is liver fibrosis.
If this exposure is continued, cirrhosis can also develop, which greatly increases the risk of liver cancer.
Furthermore, non-alcoholic fatty liver disease (NAFLD) can easily occur if people live in polluted areas, particularly because pollutants cause metabolic disorders. The debilitating effect of suffering from NAFLD and fibrosis is the reduced liver function.
Hence, it can be seen how horribly the liver can be damaged by exposure to pollutants.
There are certain risk factors which increase the damage caused by air pollution. For instance, if you have imbalanced and high-fat diets, you are more likely to develop NAFLD.
Similarly, alcohol abuse can also accelerate liver damage initiated by air pollutants.