Environment Pollution The 10 Worst Forms of Pollution By Bryan Nelson Bryan Nelson Twitter Writer SUNY Oswego University of Houston Bryan Nelson is a science writer and award-winning documentary filmmaker with over a decade of experience covering technology, astronomy, medicine, animals, and more. Learn about our editorial process Updated December 2, 2019 Photo: rey perezoso/Flickr [CC by SA-2.0] Share Twitter Pinterest Email Environment Planet Earth Climate Crisis Pollution Recycling & Waste Natural Disasters Transportation For everything we take from the Earth, there is a byproduct or consequence. Perhaps pollution is a symptom of nature's imbalance. Some people reap from the Earth, but countless others become sick, displaced or harmed due to the resulting pollution — affecting wildlife and more. On the off chance that a guilty conscience is an unknown symptom of overexploitation, here's a list of the 10 worst forms of pollution and their effects on humans. 1 of 10 Oil spills Gerald Herbert/AP. In the wake of the Gulf oil spill, the harmful effects of marine oil spills are obvious. Birds, fish and other marine life can be devastated from a spill, and the ecosystems often take decades to recover. The oil is ingested by some animals, allowing pollutants to enter the food chain, harming fisheries and other industries in the region. Many people don't realize that most oil pollution actually comes from land-based activity. One way or another, oil has seeped into nearly all of Earth's ecosystems. 2 of 10 Radioactive waste Photo: By leshiy985/Shutterstock Most radioactive waste comes as a result of nuclear power plants and nuclear weapons reprocessing, but it can also be the byproduct of medical and industrial procedures, coal or mineral mining, or oil processes. All radioactive waste carries the potential for water and air contamination. Radiation poisoning can cause severe genetic damage and may result in cancer. Some forms of radioactive waste can take thousands of years to decay, so once contamination occurs, the problem is often there to stay. 3 of 10 Urban air pollution Nagyman/Flickr. According to the World Health Organization, 2.4 million people die every year primarily because of air pollution. Urban areas such as Los Angeles, Mumbai, Cairo, Bejing and many of the world's most populated cities have the worst air quality. Air pollution has been strongly correlated with increased rates of asthma, and pollution from automobiles has a strong link to pneumonia-related deaths. One of the worst cases of urban air pollution happened in London in 1952, when about 8,000 people died over the course of a few months because of a single smog event. 4 of 10 Mercury poisoning redjar/Flickr. Most man-made mercury pollution is emitted by coal power plants, but mercury can also be a byproduct of gold mining, cement production, iron and steel production and waste disposal. Once in the environment, mercury can accumulate in the soil, water and atmosphere. It is particularly apparent in the marine food chain. The consumption of fish is by far the most significant source of mercury contamination in humans. Some effects of mercury poisoning include impaired cognitive function, kidney failure, loss of hair, teeth or nails, and extreme muscle weakness. Mercury Pollution in Clear Lake, California: History and Environmental Impact 5 of 10 Greenhouse gases Taras Kalapun/Flickr. The most common greenhouse gases are water vapor, carbon dioxide, methane, nitrous oxide and ozone. Carbon dioxide from the burning of fossil fuels has greatly increased since the Industrial Revolution. As greenhouse gases accumulate in the atmosphere, they cause overall warming and climate change. A few of the profound effects of rapid climate change include rising sea levels, loss of biodiversity and the melting of snowpack, which could threaten the world's fresh water supply. 6 of 10 Pharmaceutical pollution Mahesh Kumar/Associated Press. Pharmaceutical waste is becoming one of the world's biggest pollution concerns. Millions of doses of drugs are prescribed to people annually, and even more antibiotics are given to livestock. Those chemicals eventually make their way into the water supply. There is a natural risk to human health, but the bigger fear is that the pollution will ease the evolution of superbugs — bacteria that are immune to antibiotics. 7 of 10 Plastics Photo: By AfriramPOE/Shutterstock Many plastics are toxic. Vinyl chloride (PVC), is a known carcinogen, and bisphenol A (BPA) can disrupt endocrine function, can cause insulin resistance and it has been linked to heart disease. Plastics biodegrade slowly, in some cases lasting for hundreds of thousands of years. Waste accumulated from excessive use of plastics has become a worldwide problem. Gigantic islands of plastic trash have been known to accumulate in the North Pacific Gyre, the most famous of which is the Great Pacific Ocean Garbage Patch. 8 of 10 Untreated sewage Daniel Berehulak/Getty Images. Lackluster sewage treatment in some parts of the world is a major source of disease and water contamination. In Latin America only 15 percent of wastewater is treated, and sewage treatment is virtually unheard of in sub-Saharan Africa. In addition to the sanitation hazard, untreated sewage also allows for redistribution and accumulation of other pollutants in the water table. 9 of 10 Lead poisoning National Institute for Occupational Safety and Health/Wiki Commons/CC License. Lead is toxic and is harmful to most of the body's organs, including the heart, kidneys, nervous system, reproductive system, bones and intestines. It is especially dangerous to children because their bodies are still developing. Lead was a common component of paint until 1977, and is still used in certain kinds of paints. It can leak into the water and food supplies. Another major cause of contamination is occupational exposure in industrial settings and plants that process lead-acid batteries. 10 of 10 Agricultural pollution santiago nicolau/Flickr. Pesticides, chemicals and untreated manure are the most dangerous forms of agricultural pollution because they end up in the water supply. Excessive agricultural runoff can prompt the growth of large algal blooms, which starve waterways of oxygen and create "dead zones." Excessive erosion can also be a problem, and even accidental milk spillage from dairies can be a serious contaminant. According to the Environmental Protection Agency, half of all surface water pollution in the U.S. is attributable to agricultural sources.