Exposures to environmental pollutants and toxins are unavoidable no matter they are controllable or non-controllable. Uncontrollable source of pollutants include air pollution, pesticides, chemicals. Controllable source of environmental pollutants can be indoor air pollutants, household cleansers, and cigarette smoke. The effect of environmental pollutants and toxins on the health and wellness has been extensively studied. This article discusses the potential impact of environmental pollutants and toxins on aspects of skin health including how they can affect the normal skin aging process.
Air Pollution (Airborne Particulate Matter)
Airborne pollutants are those particulate matters (particles, smog, dust, soot) that contain contaminating chemicals or gas. Particulate matter (PM) in the air has been associated with a broad range of health problems, especially serious respiratory and cardiovascular diseases. Airborne particulate matter is produced in various ways that can be classified as either mechanical or chemical processes. Agriculture, fuel burning, dust storms and construction are some activities that produce air pollutants. Some small particles can further react or combine with other compounds in the atmosphere. A Major source of particles are generated from burning of fossil fuels in industry, transportation, agriculture and etc. Particulate matters differ in shapes and sizes, and can be solid particles, liquid droplets or gaseous droplets. Environmental science categorize particles into two main groups according to size. PM10 is particles between 2.5 and 10 microns (micrometers) in diameter. PM2.5 is particles smaller than 2.5 microns. Fine particles can be directly emitted from combustion sources or formed secondarily from gaseous precursors (e.g. sulfur dioxide, nitrogen oxides) or organic compounds. Fine particles are generally composed of sulfate, nitrate, chloride and ammonium compounds, carbon and carbon compounds, and (heavy) metals. Fine particles can be the emissions from burning of coal, oil, diesel, gasoline, wood as well as from smelters and steel mills.
A major mechanism by which particulate matter exerts its detrimental effects is through the generation of oxidative stress (free radicals, reactive oxygen species) in the skin. For how free radicals cause signs of skin aging such as wrinkle, see article “free radical theory of skin aging”. One major way for free radical induced wrinkle formation is through its damaging effect on skin structural proteins – collagen and elastin. Fine particles in the nanosize range, particularly from sources of vehicle emissions are the most harmful to the skin. These nanoparticles generates free radicals in the skin because of their physical properties or chemical properties. It is hypothesized that these particles carrying organic chemicals and metals that can be absorbed or reach into the skin directly or indirectly and being localized in mitochondria (the cellular power plant where oxygen metabolism is occurring). They then cause to generate more reactive oxygen species -the free radical byproducts of oxygen metabolism. One such particulate matter carried chemical is PAH (polycyclic aromatic hydrocarbons). Once is absorbed, PAH can be converted to Quinone which is a hyper reactive redox molecule that can generate ROS (reactive oxygen species). Another mechanism air pollutants increase free radical in the skin is through its contact with the sun’s UV rays which increases the free radicals in the air. Air pollutant can also erode the ozone layer, allowing UV to come through which can lead to skin cancer and cause formation of free radicals to be absorbed through the skin.
Indoor Air Pollutants
Sources of indoor pollution include mold, smoke, household products, radon, carbon monoxide, materials from occupational sources such as asbestos, formaldehyde and lead. Household products that contribute to the indoor air pollution include oven and drain cleaners, laundry powder, floor polish, paint thinners, strippers and removers, pesticides, grease and rust removers, arts and craft supplies. Toxic substances in these products can cause harmful effects on the general health if inhaled, swallowed, or being absorbed through the skin. EPA has emphasized that indoor air pollutants can be 2 to 5 times higher than the levels found outside.
Creosote from stoves and fireplaces and particles from pressed wood products and foam insulation can cause dry skin and skin irritation and rashes. Particles of dust that settles in carpet and on other household surfaces can cause skin irritation. Formaldehyde is a gas that leaks from carpets, insulating foam and particle boards. Formaldehyde can cause nausea, in addition to skin and eye irritation.
Water Chemicals
Chlorine in tap water is in small amount. Studies has found that large amount of chlorine can cause skin irritation.
Heavy Metals
Heavy metals are individual metals and metal compounds that can impact human health. Toxic heavy metals to the human health include: arsenic, barium, cadmium, chromium, lead, mercury. Foods can be contaminated with heavy metals from the surrounding soil or water. Drinking water can also have contaminations of heavy metals. Metals may also be inhaled from the contaminated air as discussed in the section of air pollutants. Toxic metals enter body through drinking, eating, inhaling and skin and eye contacts. These metals are not excreted, rather, they accumulate mostly in the organs as well as in the skin, hair and bones. Arsenic is found in paints, dyes, metals, drugs, soaps, semi-conductors, and certain pesticides. Arsenic is a known carcinogen and can cause skin cancer. Long-term low level exposure can cause darkening of the skin. Chromium is used in metal alloys such as stainless steel, protective coatings on metal, magnetic tapes, paints, cement, paper, rubber, floor covering and other materials. Skin contacts can cause allergic skin reactions and skin ulcers. Metallic mercury is used to produce chlorine gas and caustic soda and is also used in thermometers, dental fillings, switches, light bulbs, and batteries. Short-term exposure to high levels of metallic mercury vapors can cause skin rashes. Silver is used to produce jewelry, silverware, dental fillings, electrical conductors, alloys and mirror. Skin contact with silver can cause mild allergic reactions such as rash, swelling and inflammation in some people.
Smoke
see article ” How Smoking Cause Skin Aging “