Chapter 1: Chemical Hazards
Environmental Health
According to the World Health Organization (WHO), an estimated 12.6 million people died as a result of living or working in an unhealthy environment in 2012. Environmental risk factors, such as air, water and soil pollution, chemical exposures, climate change, and ultraviolet radiation, contribute to more than 100 diseases and injuries (World Health Organization, c). Clean air, both indoors and outdoors, a stable climate, adequate water, personal cleanliness, sanitation and hygiene, safe use of chemicals, protection from radiation, sound waste management, healthy and safe workplaces, health-supportive cities and built environments, and sustainable diet are essential for ensuring good health (World Health Organization, 2022b). Preventive action through creating healthier environments should therefore be an important component of most disease control strategies (World Health Organization, 2022b).
Clean air, a stable climate, adequate water and personal cleanliness (WASH), safe use of chemicals, protection from radiation, sound waste management, healthy and safe places of work, health-supportive cities and built environments, diets with low impact on the environment, and preserved diversity for living things.
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Chemical Hazards
More than 160 million chemicals are known to humans. About 40,000 to 60,000 of them can be found in commerce; 6,000 of these account for more than 99% of the total volume of chemicals in commerce around the world. Chemicals, whether of natural origin or produced by human activities, are part of our environment. Manufactured chemicals include industrial and agricultural products such as pesticides, petroleum products, and processed metals. Some chemicals are manufactured for specific uses, while others are unwanted by-products, including wastes, or products of combustion such as harmful gasses and particulates from industrial processes and the burning of fuel (World Health Organization, 2022b).
All people come in contact with chemicals as part of normal life. "Chemicals may enter the human body through different means, such as inhalation (breathing in the vapors); ingestion (swallowing the chemical); injection (by some mechanical means under the skin); or absorption (skin contact). These different methods can occur in any situation, not just in a workplace" (OSHA, ). Many of the chemicals people use and are exposed to are harmless or even helpful; others can be a threat and are hazardous to people’s health and the environment. Levels of exposure and resulting health impacts are determined by social as well as biological factors. Men, women, and children are exposed to different kinds and levels of chemicals and are exposed with different frequency. In addition, men, women, and children vary in the way exposure to hazardous chemicals affects them (World Health Organization, 2022b).
This first unit will specifically cover the hazardous chemicals of dioxins, PCBs, and benzene, the heavy metals of lead, mercury and cadmium and naturally occurring asbestos.
Dioxins
Basic Information
Dioxins are lasting and accumulate in the food chain, mainly in the fatty tissue of animals. Once dioxins enter the body, they last a long time because of their chemical stability and their ability to be absorbed by fat tissue, where they are then stored in the body. Their half-life in the body is estimated to be 7–11 years. More than 90% of human exposure to dioxins is through the food supply: mainly meat and dairy products, fish, and shellfish (World Health Organization, 2016).
Characteristics
Pure dioxin looks like white crystalline needles. In the environment, however, it generally is dispersed and attached to soil and dust particles and is invisible to the eye (EPA, c).
Uses
There is no known use for dioxins. It is created as a byproduct in various industrial and residential operations. It is often created during the production of chlorinated organic compounds, such as pesticides and herbicides. Chlorine bleaching of pulp and paper and other industrial processes can also create small quantities of dioxins. Combustion processes such as waste incineration or burning fuels like wood, coal or oil can form dioxins. Backyard and household trash burning contributes to the number of dioxins released into the environment (EPA, c).
Health Effects
Dioxins are highly harmful and can cause reproductive and developmental problems, damage the immune system, interfere with hormones, and can cause cancer (EPA, c). Short-term exposure of humans to high levels of dioxins may result in skin lesions, such as chloracne and irregular darkening of the skin (EPA, c).
Controls
Proper incineration of contaminated material is the best available method of preventing and controlling exposure to dioxins. Strict control of industrial processes can also reduce the creation of dioxins. On a personal level, removing excess fat from meat and consuming low-fat dairy products can reduce exposure (World Health Organization, 2016).
Polychlorinated Biphenyls (PCBs)
Basic Information
Polychlorinated Biphenyls (PCBs) are a group of man-made organic chemicals consisting of carbon, hydrogen and chlorine atoms and are from the family known as chlorinated hydrocarbons. In the United States, PCBs were commercially manufactured from 1929 until production was banned in 1979 by the Toxic Substances Control Act (TSCA). PCBs do not readily break down once in the environment. They can remain for long periods cycling between air, water and soil. PCBs can be carried long distances and have been found in snow and sea water in areas far from where they were released into the environment. Like dioxins they are known for bioaccumulation in the food chain (EPA, e).
Characteristics
PCBs have no known taste or smell, and range in consistency from light-colored liquids to yellow or black waxy solids. Because PCBs are non-flammable, chemically stable, have a high boiling point and electrical insulating properties, they are very useful in commercial and industrial operations (EPA, e).
Uses
PCBSs have been used in products such as electrical transformers and capacitors, electrical equipment including voltage regulators, switches and electromagnets, oil used in motors and hydraulic systems fluorescent light ballasts, cable and thermal insulation, caulking, plastics and carbonless copy paper (EPA, e).
Health Effects
Studies in animals provide conclusive evidence that PCBs cause cancer. Studies in humans raise further concerns regarding the potential carcinogenicity of PCBs. Taken together, the data strongly suggest that PCBs are probable human carcinogens. PCBs can also affect the immune system, reproductive system, nervous system and endocrine system (EPA, e). Skin exposure can lead to a condition called chloracne.
Controls
The main way to control PCBs is by banning its production. For existing PCBs it is recommended to provide professional remediation and disposal options.
The picture above shows how dioxins and PCBs (the orange dots) are produced in industry and make their way into the air and water. Then they steadily move up through the food chain accumulating in the fat of the host species.
Benzene
Basic Information
Industrial processes are the main sources of benzene in the environment. Benzene levels in the air can be elevated by emissions from burning coal and oil, benzene waste and storage operations, motor vehicle exhaust, evaporation from gasoline service stations and disposal of products containing benzene, and gasoline leaks from underground storage tanks release benzene into water and soil. Natural sources of benzene, which include gas emissions from volcanoes and forest fires, also contribute to the presence of benzene in the environment. Benzene is also present in crude oil and gasoline. Tobacco smoke is another source of benzene in the air, particularly indoors. The average smoker (32 cigarettes per day) takes in about 1.8 milligrams (mg) of benzene per day. This amount is about 10 times the average daily intake of benzene by nonsmokers (ATSDR, b).
Characteristics
Benzene is a colorless liquid with a sweet odor. It evaporates into air very quickly and dissolves slightly in water. Benzene is highly flammable (ATSDR, b).
Uses
Benzene was first discovered and isolated from coal tar in the 1800s. Today, benzene is made mostly from petroleum. Various industries use benzene to make other chemicals, such as styrene (for Styrofoam® and other plastics), cumene (for various resins), and cyclohexane (for nylon and synthetic fibers). Benzene is also used in the manufacturing of some types of rubbers, lubricants, dyes, detergents, drugs, and pesticides (ATSDR,b).
Health Effects
At low levels benzene can cause drowsiness, dizziness, rapid heart rate, headaches, tremors, confusion, and unconsciousness. At very high levels it can even cause death. Chronic exposure to benzene causes problems in the blood including harmful effects in the tissues that form blood cells (aplastic Anemia), and issues in the bone marrow. Long term exposure can also cause cancer of the blood-forming organs Leukemia. and has been associated with acute myeloid leukemia (AML) (ATSDR, b). The graphic below shows some of the main health effects of benzene and where benzene might be found.
Controls
Gasoline and cigarette smoke are two main sources of human exposure to benzene. Benzene exposure can be reduced by limiting contact with these sources. Because people are exposed to benzene from both active and passive second-hand smoke, families are encouraged to not smoke in their house, in enclosed environments, or near their children.
Benzene is a major component of gasoline and used in many manufacturing processes. Increased levels of benzene can be found at fueling stations, and in air emissions from manufacturing plants and hazardous waste sites. Living near gasoline fueling stations or hazardous waste sites may increase exposure to benzene. People are advised not to have their families play near fueling stations, manufacturing plants, or hazardous waste sites (ATSDR, b).
Lead
Basic Information
WHO estimates that almost 1 million people die before they reach old age because of the effects of lead exposure (World Health Organization, 2022a). Lead is a naturally occurring element found in small amounts in the earth’s crust. It can be found in all parts of our environment such as, the air, the soil, the water, and even inside our homes (EPA, d). Lead is a toxicant that accumulates and affects multiple body systems and is particularly harmful to young children. Children are often exposed to lead by eating paint chips. Lead in the body is distributed to the brain, liver, kidney, and bones. It is stored in the teeth and bones, where it accumulates over time. Human exposure is usually assessed through the measurement of lead in blood. Lead in bone is released into the blood during pregnancy and becomes a source of exposure to the developing fetus. There is no level of exposure to lead that is known to be without harmful effects (World Health Organization, 2022c).
Characteristics
In pure form, lead is silvery in appearance. Lead metal oxidizes and turns bluish- gray when exposed to air. It is soft enough to be scratched with a fingernail. It is dense, malleable, and readily fusible. Its properties include a low melting point, high density, acid resistance; and chemical stability in air, water, and soils (EPA, b).
Uses
There are many sources of lead exposure in industrial settings like mining and smelting, recycling of electronic waste and lead-acid batteries, plumbing and ammunition. Exposure can also occur from lead paint in homes, schools, hospitals, and playgrounds. Children can ingest flakes and dust, from lead-painted toys or surfaces or be exposed through lead-glazed ceramics and some traditional medicines and cosmetics (World Health Organization, 2022c).
Health Effects
Lead is toxic to multiple body systems, including the central nervous system and brain, the reproductive system, kidneys, the cardiovascular system, the blood system and the immune system (World Health Organization, 2022c). Children six years old and younger are most at risk to the effects of lead. Even low levels of lead in the blood of children can result in behavior and learning problems, lower IQ, hyperactivity, slowed growth, hearing problems and anemia. Adults exposed to lead can suffer from cardiovascular effects, increased blood pressure, incidence of hypertension, decreased kidney function, and reproductive problems (in both men and women). During pregnancy, lead is released from the mother's bones along with calcium and can pass from the mother exposing the fetus or the breastfeeding infant to lead. This can result in serious effects to the developing fetus and infant (World Health Organization, 2022c).
Controls
The WHO calls upon all countries to ban lead paint, identify and eliminate all sources of childhood lead exposure, and educate the public regarding the dangers of misusing lead-containing products (World Health Organization, 2022c). Removing lead paint and old lead pipes has reduced overall lead exposures, however, the removal of lead from gasoline in the United States caused a significant decline in blood lead levels. The chart below created by the Center of Disease Control (CDC) shows how the average blood lead level, dropped as lead was taken out of gas.
As of July 2021, leaded fuel for cars is no longer sold anywhere in the world. However, more needs to be done to phase out lead paint; so far, only 45% of countries have introduced legally binding controls on lead paint (EPA, d).
Mercury
Basic Information
Mercury is a naturally occurring element found in rock in the earth's crust. The main way that people are exposed to mercury is by eating fish and shellfish that have high levels of methylmercury, a highly toxic form of mercury, in their tissues. A less common way people are exposed to mercury is breathing mercury vapor. This can happen when mercury is released from a container, or from a product or device that breaks. If the mercury is not immediately contained or cleaned up, it can evaporate into the air (EPA, a).
When they eat fish and shellfish that contain the compound.
Characteristics
Elemental or metallic mercury is a shiny, silver-white metal, historically referred to as quicksilver, and is liquid at room temperature. If heated, it can become an invisible, odorless, toxic vapor (EPA, a).
Uses
Elemental mercury is used in older thermometers, fluorescent light bulbs and some electrical switches. Inorganic mercury compounds are still being widely used in skin lightening soaps and creams. Mercuric chloride is used in photography and as a topical antiseptic and disinfectant, wood preservative, and fungicide (EPA, a).
Health Effects
Mercury exposure at high levels can harm the brain, heart, kidneys, lungs, and immune system of people of all ages. High levels of methylmercury in the bloodstream of babies developing in the womb and young children may harm their developing nervous systems, affecting their ability to think and learn (EPA, a).
Elemental and methylmercury are toxic to the central and peripheral nervous systems. The inhalation of mercury vapor can produce harmful effects on the nervous, digestive and immune systems, lungs and kidneys, and may be fatal. Neurological and behavioral disorders may be observed after inhalation, ingestion or dermal exposure of different mercury compounds. Symptoms include tremors, insomnia, memory loss, neuromuscular effects, headaches and cognitive and motor dysfunction (World Health Organization, 2017). Chronic exposure to Mercury can lead to other neurological effects known as erethism. Mad-hatter disease is the term commonly used for erethism.
Controls
There are several ways to prevent adverse health effects of mercury, they include, promoting clean energy that does not burn coal, stopping the use of mercury in gold mining, eliminating the mining of mercury, and phasing out non-essential mercury-containing products (World Health Organization, 2017).
Cadmium
Basic Information
Cadmium is a heavy metal found naturally in the earth’s crust. It is generally present in the environment at low levels; however, human activity has greatly increased levels in the environment (World Health Organization, b). All soils and rocks, including coal and mineral fertilizers, contain some cadmium. Most cadmium used in the United States is extracted during the production of other metals like zinc, lead, and copper. Exposure to cadmium happens mostly in the workplace where cadmium products are made. The general population is exposed from breathing cigarette smoke or eating cadmium contaminated foods (ATSDR, c).
Characteristics
Cadmium is a heavy metal, that is a very flexible malleable metal. It is a silver-white solid, with some hints of blue (NIOSH CDC, ). It is resistant to corrosion and insoluble in water (ATSDR, c ).
Uses
Cadmium is used in many industries. It’s used in the manufacturing of some batteries and solar cells, electroplating, and silver soldering. Construction workers involved in demolition can be exposed to dust containing cadmium. Other examples of workers at risk of cadmium exposure include, workers exposed to cadmium-containing pigments and coatings, factory workers in plants that manufacture Ni-Cd batteries, workers in electroplating shops or factories, electronic recycling workers exposed to telephone and electric cables (NIOSH CDC, ).
Health Effects
Cadmium is a highly toxic carcinogenic substance that is harmful to most of the body’s systems, especially to the lungs, bones, and kidneys (NIOSH CDC, ). Breathing high levels of cadmium can severely damage the lungs. Eating food or drinking water with very high levels severely irritates the stomach, leading to vomiting and diarrhea. Long-term exposure to lower levels of cadmium in air, food, or water leads to a buildup of cadmium in the kidneys and possible kidney disease. Other long-term effects are lung damage and fragile bones (ATSDR, c). Cadmium accumulates primarily in the kidneys and its biological half-life in humans is 10–35 years. This accumulation may lead to kidney dysfunction, disturbances in calcium metabolism, the creation of kidney stones, and effects on bone such as Osteomalacia (softening of the bones) osteoporosis (bones become brittle and fragile). High inhalation exposure to cadmium oxide fumes results in acute pneumonitis (inflammation of the alveoli) with pulmonary edema (collection of water in the lungs) and causes lung cancer (World Health Organization, 2019). The picture below shows not just the health effects of cadmium but all those of lead and mercury.
Controls
Cadmium exposure can be reduced by increasing the safe and effective recycling of cadmium, minimizing release and discharges from activities such as mining and waste management, promoting safe working conditions for workers of cadmium-containing products, and promoting the elimination of use of cadmium in products such as toys, jewelry and plastics (World Health Organization, b). On a family level, exposures can be reduced in the home by storing substances that contain cadmium safely, and keep nickel-cadmium batteries out of reach of young children. Avoid smoking in enclosed spaces like inside the home, and a balanced diet can reduce the amount of cadmium taken into the body from food and drink (ATSDR, c).
Reduce: Airborne release from mining, waste incineration, application of sewage sludge to the land, use of phosphate fertilizers and cadmium-containing manure. Recycle cadmium and restrict uses that aren't friendly to the environment.
Asbestos
Basic Information
Currently, about 125 million people in the world are exposed to asbestos at work. Approximately half of the deaths from occupational cancer are estimated to be caused by asbestos. In addition, it is estimated that several thousand deaths annually can be attributed to exposure to asbestos in the home (World Health Organization, a). People may be exposed to asbestos by breathing tiny asbestos fibers in the air. The asbestos gets into the air from natural deposits of asbestos in the earth or from past or current commercial products that contain the minerals. Asbestos fibers usually get into the air when something disturbs them in soil, rock, or older products, such as: weathering or erosion of natural deposits of asbestos at the ground surface or old asbestos-containing products, crushing rock with natural deposits of asbestos, handling, cutting, or crushing old asbestos-containing products, for example, during building renovation or demolition projects, and disturbing soil contaminated by natural surface deposits or old asbestos-containing products during recreational or other outdoor activities (ATSDR, a).
Characteristics
Asbestos occurs naturally in certain types of rock. Large amounts of asbestos in rocks can look like long fibers, but each asbestos fiber is too small to see with the naked eye. Asbestos fibers do not dissolve in water or evaporate. They resist heat and fire and cannot be broken down easily by chemicals or bacteria (ATSDR, a). Since asbestos is threadlike, it can be woven into fabrics.
Uses
Because of its sturdy properties, asbestos was mined and used in making many products, including insulation, fireproofing and acoustic materials, wallboard, plaster, cement, floor tiles, brake linings, and roofing shingles. It has also been used in products such as automobile brakes and roofing materials. Asbestos may also be present in other commercial products, such as vermiculite and talc (ATSDR, a).
Health Effects
Asbestosis is scarring in the lungs caused by breathing asbestos fibers. Oxygen and carbon dioxide do not pass in and out of scarred lungs easily, so breathing becomes harder. Asbestosis usually occurs in people who have had very high exposures over a long time, but years may pass before any symptoms appear (ATSDR, a ).
Lung cancer is a malignant tumor that invades and blocks the lung’s air passages. Smoking tobacco combined with asbestos exposure greatly increases the chance of developing lung cancer (ATSDR, a).
Mesothelioma is a rare cancer of the membrane that covers the lungs and chest cavity (pleura), the membrane lining the abdominal cavity (peritoneum), or membranes surrounding other internal organs. Signs of mesothelioma may not appear until 30 to 40 years after exposure to asbestos (ATSDR, a ).
Controls
To best control asbestos exposure governments should stop the use of all types of asbestos, replace asbestos with safer alternatives substitutes, take measures to prevent exposure to asbestos in place and during asbestos removal, and improve early diagnosis and treatment of asbestos-related diseases (World Health Organization, a ). People who live in older homes should avoid disturbing materials that might contain asbestos, including pipe and furnace insulation, siding, flooring, and popcorn ceilings installed from the 1950s to the 1970s. They should hire contractors who know how to conduct safe asbestos removal and disposal to avoid contaminating the rest of the home or the environment. People who work around asbestos, or materials that contain it, should get proper training for handling asbestos (ATSDR, a). Asbestos workers should also wear the proper personal protective equipment for asbestos abatement workers such as those items pictured below.
Conclusion
All people are exposed to chemical substances in at least one form or another. As specialist in the field, we can watch for symptoms of exposure and recommend controls that can protect the health of others.
References
ATSDR. (a). Asbestos Exposure and Reducing Exposure . Retrieved Dec 7, 2022, from https://www.atsdr.cdc.gov/asbestos/asbestos_exposure.html
ATSDR. (b). Benzene. Retrieved Dec 7, 2022, from https://www.atsdr.cdc.gov/sites/toxzine/benzene_toxzine.html
ATSDR. (c). ToxFAQs for Cadmium. Retrieved Nov 30, 2022, from https://wwwn.cdc.gov/TSP/ToxFAQs/ToxFAQsDetails.aspx?faqid=47&toxid=15
EPA. (a). Basic Information about Mercury. Retrieved Nov 30, 2022, from https://www.epa.gov/mercury/basic-information-about-mercury
EPA. (b). Lead and Lead Compounds. Retrieved Nov 30, 2022, fromhttps://ordspub.epa.gov/ords/guideme_ext/f?p=guideme:gd:0::::gd:lead_guidance_4_1#:~:text=Its%20properties%20include%20a%20low,and%20mechanical%20vibration%20(11).
EPA. (c). Learn about Dioxin. Retrieved Nov 30, 2023, from https://www.epa.gov/dioxin/learn-about-dioxin
EPA. (d). Learn about Lead. Retrieved Nov 30, 2022, from https://www.epa.gov/lead/learn-about-lead
EPA. (e). Learn about Polychlorinated Biphenyls (PCBs). Retrieved Nov 30, 2022, from https://www.epa.gov/pcbs/learn-about-polychlorinated-biphenyls-pcbs
NIOSH CDC. Cadmium
Retrieved 30 Nov 2023, from https://www.cdc.gov/niosh/topics/Cadmium/
OSHA, Hazard Communication Retrieved 15 Jan 2023, from
https://www.osha.gov/sites/default/files/2019-03/hazardcommunication.pdf
World Health Organization. (a). Asbestos: elimination of asbestos-related diseases. Retrieved Dec 7, 2017, from https://www.who.int/news-room/fact-sheets/detail/asbestos-elimination-of-asbestos-related-diseases
World Health Organization. (b). Cadmium. Retrieved Nov 30, 2022, from https://www.who.int/teams/environment-climate-change-and-health/chemical-safety-and-health/health-impacts/chemicals/cadmium
World Health Organization. (c). An estimated 12.6 million deaths each year are attributable to unhealthy environments. Retrieved Nov 17, 2022, from https://www.who.int/news/item/15-03-2016-an-estimated-12-6-million-deaths-each-year-are-attributable-to-unhealthy-environments
World Health Organization. (2016). Dioxins and their effects on human health. Retrieved Nov 17, 2022, from https://www.who.int/news-room/fact-sheets/detail/dioxins-and-their-effects-on-human-health
World Health Organization. (2017). Mercury and health. Retrieved Nov 30, 2022, from https://www.who.int/news-room/fact-sheets/detail/mercury-and-health#:~:text=Exposure%20to%20mercury%20%E2%80%93%20even%20small,%2C%20kidneys%2C%20skin%20and%20eyes.
World Health Organization. (2019). PREVENTING DISEASE THROUGH HEALTHY ENVIRONMENTS. ().WHO.
World Health Organization. (2022a). Almost 1 million people die every year due to lead poisoning, with more children suffering long-term health effects. Retrieved Nov 30 2023, from https://www.who.int/news/item/23-10-2022-almost-1-million-people-die-every-year-due-to-lead-poisoning--with-more-children-suffering-long-term-health-effects
World Health Organization. (2022b). Compendium of WHO and other UN guidance on health and environment. ().
World Health Organization. (2022c). Lead poisoning. https://www.who.int/news-room/fact-sheets/detail/lead-poisoning-and-health. Retrieved Nov 30, 2023, from
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