Ecotoxicology And Environmental Toxicology

Effects of chemical pollution

There are three main routes of exposure, or ways a substance can enter your body.

• Breathing (inhalation): Inhalation of chemical gases, mists or dusts in the air.

• Skin or Eye Contact: Contact of chemicals with skin or eyes. They can damage the skin or be absorbed through the skin into the bloodstream.

• Ingestion (choking): This can occur when chemicals have been spilled or landed on food, drink, cigarettes, beards, or hands.

Once the chemicals enter your body, some of them can enter your bloodstream and reach internal “target” organs such as the lungs, liver, kidneys, or nervous system.

Chemicals come in the form of solids, liquids, powders, vapours, gases, fibres, mists and vapours. Sometimes chemicals come in a form you can’t see or smell, making them hard to spot. An acute effect of a pollutant occurs rapidly after exposure to a large amount of that substance.

A chronic effect of pollutants results from exposure to small amounts of a substance over a long period of time. If so, the effect may not be immediately noticeable. Chronic effects are difficult to measure because they may not be seen for years. Low levels of radiation exposure and moderate alcohol consumption are believed to produce chronic effects.

A substance that can be cancerogenic and cause cancer (uncontrolled cell growth), either alone or in combination with another substance. Examples include formaldehyde, asbestos, radon, vinyl chloride, and tobacco.

Teratogen – A substance capable of causing physical harm to a developing embryo. Examples are alcohol and cigarette smoke.

Mutagen – Material that causes genetic changes (mutations) in DNA. Examples include radioactive substances, X-rays and ultraviolet radiation.

A neurotoxic substance that may have an adverse effect on the chemistry, structure, or function of the nervous system. examples are lead and mercury.

Endocrine disruptor – A chemical that can interfere with the body’s endocrine (hormonal) system and cause adverse developmental, reproductive, neurological, and immunological effects in both humans and wildlife. A variety of natural and man-made substances are believed to cause endocrine disruption, including pharmaceuticals, dioxins, and dioxin-like compounds, arsenic, polychlorinated biphenyls (PCB), DDT, and other pesticides, and plasticizers such as bisphenol A (BPA).

Scientists have known for centuries that almost all substances are toxic in sufficient amounts. For example, living organisms require small amounts of selenium for proper function, but large amounts can cause cancer.

A lethal dose for 50% of a population of test animals is called the 50% lethal dose or LD50. Determination of the LD50 is required for new synthetic chemicals to provide a measure of their toxicity. A dose that produces a significant response (e.g. hair loss, growth failure) in 50% of a population is referred to as the effective dose or ED50.

Some toxins have a threshold amount below which there is no apparent effect on the exposed population. Contamination of air, water or soil with potentially harmful substances can affect any individual or community.

Chemical Pollutants

Arsenic is a naturally occurring element normally found in our environment in water, soil, dust, air and food. Arsenic levels can vary regionally due to agricultural and industrial activities as well as from agriculture and smelting tends to bind strongly to soil and is expected to remain near the surface of the earth for hundreds of years as a source of long-term exposure.

Wood treated with CCA is commonly found on decks and railings in existing homes and outdoor structures such as playgrounds. Arsenic in drinking water is a problem in many third-world countries.

Arsenic can also be found in foods, including rice and some fish, where it is present due to absorption from soil and water. Most arsenic enters the body through the ingestion of food or wat It can also enter the body through inhalation of dust containing arsenic.

Researchers are finding that even in small amounts, arsenic can alter the body’s endocrine system. Arsenic is also a known human carcinogen that has been linked to skin, lung, bladder, kidney, and liver cancer.

Mercury exists in many forms; The types that humans are commonly exposed to are methylmercury and elemental mercury. Elemental mercury is a shiny, silvery-white liquid at room temperature that can produce a noxious, odorless vapor. Methylmercury, an organic compound, can accumulate in the bodies of long-lived predatory fish. Products sold today that contain small amounts of mercury include fluorescent lamps and button batteries. Although fish and shellfish have many nutritional benefits, eating large amounts of fish increases a person’s exposure to mercury.

Bisphenol A (BPA) is a bulk synthesized chemical used primarily in the manufacture of polycarbonate plastics and epoxy resins. Polycarbonate plastics have many applications including use in some food and beverage containers, e.g. Discs, impact-resistant safety equipment and medical devices. Epoxy resins are used as paints to coat metal products such as food cans, bottle caps, and water supply pipes. Certain dental sealants and composites may also contribute to exposure to BPA.

The main source of BPA exposure for most people is diet, use of polycarbonate tableware, food containers, water bottles, and baby bottles. The extent to which BPA leaches into liquid from polycarbonate bottles may depend more on the temperature of the liquid or bottle than the age of the container.

Some animal studies suggest that infants and children are most vulnerable to the effects of BPA.
Parents and caregivers can make personal choices to reduce their infants and children’s exposure to BPA:
• Do not use polycarbonate plastic food containers in the microwave., but over time it can degrade from excessive exposure to high temperatures.
• Some, but not all, plastics marked with
recycling codes 3 or 7 can be made with BPA.
• Reduce canned food.
• If possible, opt for glass, porcelain or stainless steel.

Phthalates are a group of synthetic chemicals used to soften and increase the flexibility of plastics and vinyl. Polyvinyl chloride is made softer and more flexible by the addition of phthalates. Personal care products included perfumes, hairspray, soap, shampoo, nail polish, and skin moisturizers. They are used in consumer products such as soft plastic and vinyl toys, shower curtains, wallpaper, vinyl mini-curtains, food wraps and plastic packaging.

Exposure to low concentrations of phthalates can result from eating food packaged in plastic containing phthalates or breathing dust in rooms with mini vinyl blinds, wallpaper, or newly installed floors that contain phthalates. We can be exposed to phthalates through drinking water as well. Phthalates are suspected of being endocrine disruptors.

Lead is a naturally occurring metal in rocks and soils in the earth’s crust, it is also produced by burning fossil fuels such as coal, oil, gasoline, and natural gas; Lead is used in the manufacture of batteries, pipes, roofing, scientific electronic equipment, military positioning systems, medical equipment, and X-ray and nuclear radiation shielding products. It is used in ceramic glazes and glassware.

The part of the body most sensitive to lead exposure is the central nervous system, particularly in children who are more susceptible to lead poisoning than adults. A child who ingests large amounts of lead can develop brain damage that can cause seizures and death; the child may also develop blood anemia, kidney damage, colic, and muscle weakness. Repeated low-level lead exposure can disrupt a child’s normal mental and physical growth and cause learning or behavioral problems.

Exposure to high levels of lead- in pregnant women can result in miscarriage, premature birth, and smaller babies. Repeated or chronic exposure can cause lead to build-up in the body, which can lead to lead poisoning.

Formaldehyde is a colorless, flammable gas or liquid with a pungent, suffocating odor. It is naturally found in small, harmless amounts in the human body. Wood products (eg, chipboard, plywood, and furniture ), automobile exhaust, cigarette smoke, paints and varnishes, and permanently pressed carpets and fabrics, commercially applied nail polishes and floor finishes emit formaldehyde.

In general, indoor concentrations are consistently higher than in outdoor areas, because many building materials, consumer products, and textiles emit formaldehyde. Levels of formaldehyde measured in indoor air range from 0.02 to 4 parts per million (ppm). Levels of formaldehyde in outdoor air range from 0.001 to 0.02 ppm in urban areas.

Radiation is the energy emitted by atoms and everything around us. Every day we are exposed to radiation from natural sources such as earth, rock, and the sun. We are also exposed to radiation from artificial sources such as medical X-rays and smoke detectors. We are even exposed to small amounts of radiation from cross-country flights, television, and even some building materials.

Some types of radioactive materials are more dangerous than others. It is therefore important to treat radiation and radioactive substances with care to protect health and the environment.

Radon is a natural, colorless, and odorless radioactive gas. It comes from the natural decomposition of uranium, or thorium, which is found in almost all soils. It usually climbs through the bottom of and enters the house through cracks in floors, walls, and foundations. It can also be released through building materials or well water. Radon decays rapidly and releases radioactive particles. Long-term exposure to these particles can cause lung damage.