Common Environmental Hazards

You can classify environmental hazards as either traditional or modern. Traditional hazards, which are often linked to poverty, mostly affect low-income individuals and those from developing countries. Modern hazards are a result of technological advancement and can be found in industrialized nations where the risk of traditional hazards is low. The traditional hazards’ impact is greater than that of modern hazards 10 times in Africa, 5 times in Asian countries (except China), 2.5 times for Latin America and 2 times in the Middle East.

Inadequate water supply or sanitation can lead to water-related diseases that pose a huge health problem in Africa, Asia, the Pacific, and other parts of the world. In India alone, 90,000 children under five died diarrhea in 2017. Globally, 409k people died from malaria in 2019, with 94% of these deaths in Africa. A third of world households used unprocessed fuels, especially biomass (crop residues, wood and dung), for cooking and heating. This puts people, especially low-income children and women, at risk of high indoor air quality. It is the leading cause of approximately 1.6million deaths annually.

For example, urban pollution in cities is high in India, China and parts of Asia and Latin America. The “double burden” of modern and traditional environmental health threats is increasingly felt by low-income individuals. In rich countries, they are subject to a doubled death and illness burden due to all causes. They also have a 10x higher disease burden because of environmental hazards.

Biological, chemical and physical environmental dangers

Based on their causes, environmental hazards can be divided into three interrelated groups (biological, physical, and chemical). These categories can be used to distinguish between modern and traditional hazards. Indoor air pollution, for instance, can be both a conventional and chemical hazard. Different hazards may interact with and worsen each other. Floods are, for instance, a physical hazard that can spread waterborne disease (a biohazard). A chemical hazard called air pollution can cause respiratory tissue damage, making it more vulnerable to infection. Infectious diseases (biological dangers) can also weaken your immune system, making you more vulnerable to chemical hazards.

Biological Hazards

Biological hazards were the major factor in human health throughout history. Biological hazards (also known as communicable disease) are diseases that can be transmitted from pathogens. These include bacteria, fungi and parasitic worms. Bacteria is an organism that has single cells and simple cells. Some examples of bacterial disease include tuberculosis (cholera), bacterial pneumonia and dysentery.

Fungi can be found in one or many cells. They also have a different cell type to bacteria. Some fungal diseases can cause minor infections, such as yeast infections or athlete’s toes, but they can also cause serious respiratory infections (histoplasmosis and coccidioidomycosis). People with compromised immune systems are particularly vulnerable. Parasiticworms are animals of several phyla that siphon nutrients from their host. Examples of parasitic worms include the tapeworms that are commonly found in uncooked meats and blood flukes (Schistosoma).

Protozoa are similar to fungi in that they have larger and more complex cells. However, they lack the rigid cell walls found around fungal cells. Protozoa can cause malaria, African trypanosomiasis or sleeping sickness, and giardiasis. Viruses are infectious particles that are enclosed by a protein layer and have genetic information. However, they are not considered to be organisms because they lack cells. All virus-related diseases, including COVID-19, influenza and measles, as well as the human immunodeficiency viruses (HIV)/acquired immunodeficiency syndrome (AIDS), are caused by viruses. Prions (proteinaceous infectious particles) are much simpler than viruses. They lack genetic material, and only contain proteins.

Under the microscope: Red blood cells infected to the protozoan Plasmodium which causes malaria. Image by Kim Sung Lee, Janet Cox Singh, Balbir Singh. (CC-BY). Despite the fact that infectious diseases have been decreasing in death rates, with a greater proportion of deaths due to non-communicable diseases like cancer and heart disease, about one in five deaths were still from infectious diseases in 2017.

These deaths occurred in the most developing countries, with many occurring in children. Unclean water, poor sanitation and inadequate medical care are all factors that contribute to transmission and high rates of death from infectious diseases.

Chemical Hazards

Chemical hazards are harmful substances that cause harm to living organisms. There are many examples of air pollutants, including carbon monoxide and secondhand smoke, as well as heavy metals and pesticides. These contaminants can be found in a variety of commercial, residential, and industrial settings. Sometimes, environmental contaminants are harmful biologically. Toxins can also be classified by their chemical structure, effects, origin, and purpose. Carcinogen (carcinogenic agent) A substance which can cause cancer by uncontrolled cell growth. Asbestos, formaldehyde (or radon), vinyl chloride, or tobacco are some examples. Teratogen Any substance that may cause physical defects in a developing embryo. Examples are alcohol and cigarette smoking.

Mutagen is a material that causes genetic mutations (or changes) in the DNA. Radioactive substances such as radon, nuclear fuel and radioactive waste, and even nitrous acid are examples. Mutagens are also possible with certain radiation forms (see Physical Hazards). Neurotoxin Any substance that can have an adverse effect upon the chemistry, structure, or function the nervous system. Mercury and lead are examples. Endocrine disruptor A chemical which may cause a disruption in the body’s hormonal system. It can also have adverse developmental, neurological, and immune effects on both humans and wildlife.

A wide variety of substances, natural and man-made can cause endocrine disruption.


Formaldehyde can be described as a colorless and flammable gas or liquid with a pungent, intoxicating odor. It is a volatile organ compound, which is composed of carbon and hydrogen. It is also found in small amounts, but harmlessly, in the human body. Breathing in formaldehyde-containing atmospheres is the main way that we can be exposed. Industries that use or manufacture formaldehyde, as well as wood products such plywood, particle-board and furniture, automobile exhaust, cigarette smoke and paints and varnishes, as well permanent press fabrics and carpets can release formaldehyde. Formaldehyde can be found in nail polish and commercially applied flooring finishes.

There are many toxic chemicals in nail products, including formaldehyde (DBP), toluene and toluene. Because many fabrics, building materials, and consumer products emit formaldehyde, indoor environments tend to have higher concentrations than outdoor ones. Indoor levels of formaldehyde are 0.02-4 parts per Million (ppm). Outdoor levels of formaldehyde range from 0.001 – 0.02 ppm for urban areas. Heavy Metals Chemical elements of high densities that form special bonds (called metallic bonds) in which electrons are shared in a more restricted way than covalent bonds.

Examples of heavy metals are arsenic, mercury and lead. Arsenic, also known as As, is a naturally occurring element found in the environment. It is present in food, water, soil and dust. Due to natural geological processes, farming and industrial activity, arsenic levels can vary regionally. As a long-term exposure source, the arsenic from smelting or farming tends strongly to soil. CCA-treated wood is common in decks and railings of existing homes, as well as outdoor structures such a playground equipment. Underground aquifers may be found in rock or soil with high arsenic levels.

The majority of arsenic is absorbed through the ingestion or drinking of food and water. Arsenic in water is a concern in many countries including India, Bangladesh and Chile. Arsenic could also be found as a component of foods such as rice or fish. This is because it has been up taken from soil and water. Inhaling arsenic-containing dust can also lead to arsenic entering the body. Arsenic poisoning can lead to serious health conditions and a host of symptoms.

Researchers have discovered that arsenic in low levels can affect the body’s hormones. Arsenic, a human carcinogen, is associated with skin cancer, liver cancer, bladder cancer, kidney cancer, kidney cancer, bladder cancer, and lung cancer. The presence of patches of darkened skin (arsenical hyperkeratosis), in the palms of your hands can be a sign of arsenic exposure. Image and caption modified from Agency for Toxic Substances and Disease Registry/CDC. Mercury (Hg), which is a naturally-occurring metal, can be used in some products and poses a risk to your health. Mercury can be found in many forms. The most common types are elemental and methylmercury.

At room temperature, the metallic mercury is a silvery-white liquid with a strong odor. The bodies of predatory long-living fish can be contaminated by methylmercury (Biomagnification), an organic compound. Even though fish and shellfish offer many nutritional benefits to humans, excessive consumption of these fish can increase one’s mercury exposure. Consuming mercury-rich fish regularly during pregnancy can cause permanent damage to their developing fetuses. Children of these mothers might have cognitive deficits, sensory problems, motor difficulties and sensory issues.

Because of the high mercury content, the United States Environmental Protection Agency advises pregnant women and children not to eat swordfish, shark, King mackerel or tilefish. These individuals should avoid mercury-rich fish like salmon, shrimps, pollock and catfish. It is important to dispose of mercury-containing products at a hazardous waste facility in order to keep mercury out the food we eat and the atmosphere we breathe.

Button-cell batteries and fluorescent lamps are two examples of products today that may contain low levels of mercury. There are different types of fish classified according to mercury levels. The lowest levels of mercury are found in the best fish (black sea bass and catfish), and can be consumed safely up to three times per week. The best choices are carp, yellowfin, yellowfin tuna, and halibut. They are safe to consume one serving per week. Avoid sharks and swordfish. They have high mercury levels and should not be eaten.

Button-cell batteries in small devices, such as watches and hearing aids, contain mercury and should be disposed of at a hazardous waste facility. Image by Lead holder. CC-BY – SA. Lead (Pb), which is a naturally occurring metal in the Earth’s crust, can be found in rocks and soil. It is also released through mining, manufacturing and the combustion of fossil fuels, such as oil, gasoline, and natural gases. Lead is not distinctive in taste or odor. Lead is used for making pipes, batteries and roofing. It is used in ceramic glazes, and crystal glassware. Lead and other lead compounds were banned in 1978 from house paint, soldering on water pipes in 1985, gasoline in 1995, soldering on food cans and wine bottles in 1996 due to health concerns.

The U.S. Food and Drug Administration established a limit on how much lead can be used to make ceramics. Lead and lead compounds have been listed as “reasonably predicted to be human carcinogens”. It can damage almost every system and organ in your body. It can also be harmful if it is breathed in or swallowed. The central nervous system is especially sensitive to lead poisoning in children. Children are more susceptible to it than adults. Children who have swallowed large amounts of lead can suffer brain damage. This can cause death and convulsions. Recurrent low levels of lead exposure can affect a child’s mental and physical growth, and cause learning and behavioral problems. Pregnant women who are exposed to high levels can have miscarriages, premature births, or smaller babies. Chronic or repeated exposure to lead can lead to lead poisoning.

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