When you think of the term ​pollution​, the first thing you likely consider is the environmental impact. You might picture aquatic birds drenched in oil after an oil spill, or the pack ice melting in the polar regions and stranding skinny polar bears away from their prey. However, pollution doesn't just impact wildlife and the ecosystem – it can also have devastating consequences on the human body.

Researchers separate pollutants into three primary types: air pollutants, water pollutants and soil or ground pollutants. Each of these types of pollution has a multitude of different sources. For example, ​air pollution​ can come from emissions from large factories, but also from your individual car's exhaust as well. ​Water pollutants​ can include plastics and other garbage making their way into the ocean, or chemicals such as fertilizer and pesticides.

While air and water pollutants can have far-reaching impacts, ​soil pollutants​ typically impact only the immediate area unless washed into nearby water sources. In these instances, soil pollutants are the source of water pollution. However, that doesn't mean they can only impact human health if they end up as a water pollutant.

Many different types of pollutants can infect the soil in a region. Fertilizers, pesticides – even radioactive material or the byproducts of chemical production can pollute an area's soil. People can come in contact with soil pollutants in a number of different ways.

People might come in direct contact with contaminated soil. For example, a toddler crawling on the ground might have direct contact with pesticides recently applied to grass. People can also inhale or ingest soil contaminants when the wind kicks dust particles up into the air. You might also track in contaminants on your shoes.

Soil pollution can also impact any plant life, such as fruits and vegetables, grown in the area. Those plants can uptake some contaminants and consuming them can expose you to the pollutants. When they aren't cleaned properly you can also come in contact with polluted soil that has adhered to the vegetables.

Air pollution impacts human health in a variety of ways, and is especially hard on the respiratory tract and on vulnerable populations. Children, those with illnesses or pre-existing conditions such as asthma, and the elderly are all more susceptible to the impacts of air pollution than healthy adults.

Pollutants in the air, such as particulate matter, surface-level ozone and volatile organic compounds, can cause varying diseases and side effects. Some health conditions that can be caused or worsened by air pollution include:

• Heart disease
• Respiratory infection
• Lung cancer
• Asthma
• Chronic obstructive pulmonary disease (COPD)
• Bronchiolitis
• Skin diseases
• Weakened immune system

Different forms of water pollutants have different impacts on human health. Agriculture, sewage, radioactive material, oil, fracking and garbage are all sources of water pollutants. In garbage pollution, plastics break apart into tiny particles known as ​microplastics​. These microplastics accumulate in the stomachs of the fish that we consume and can result in inflammation and metabolic disorders when eaten by humans.

Chemical pollutants can contaminate water supplies and even drinking water. When the water supply in an area is not tested or treated properly, ingesting polluted water can lead to rashes, hair loss, cancer, immune system suppression, reproductive dysfunction and altered hormone levels. Water contamination famously occurred in Flint, Michigan beginning in 2014, when the city changed the water supply and failed to properly test and treat the water before providing it to their residents.

Sewage and wastewater is another source of water pollution. The World Health Organization estimates that approximately two billion people across the globe consume water sources contaminated with feces. This can cause the spread of bacterial diseases such as polio, cholera, diarrhea, hepatitis A and dysentery.