2.4.5.1 Absorption/ Distribution/Excretion
Mercury vapor is readily absorbed in the lungs, rapidly diffuses across alveolar membranes into the blood, and distributes to all tissues in the body due to its high lipid solubility. Once the vapor has entered the cell, it is oxidized to divalent inorganic mercury by tissue and erythrocyte catalase (Neustadt and Pieczenik, 2007), whereas some crosses the blood brain barrier and placenta. Inorganic mercury is poorly absorbed from the gastrointestinal tract, absorption varies depending on the inorganic compound. Exposure of mercury comes in a number of different chemical forms. Metallic mercury (Hg) is used in thermometers, dental amalgams, and some batteries. In its pure form, metallic mercury is a liquid. Contrary to popular opinion, it is not hazardous if ingested (as it is not significantly absorbed in this form). However, if left standing, or even worse, if aerosolized, for example, through attempted vacuum cleaning, metallic mercury will volatilize into a vapor that is well absorbed by the lungs. Mercurous and mercuric mercury (Hg+ and Hg2+ respectively) are encountered in some chemical, metal-processing, electrical-equipment, automotive, and building industries and in medical and dental services. Mercurous and mercuric mercury form inorganic and organic compounds with other chemicals that can be readily absorbed through ingestion. All three forms of mercury are toxic to various degree.
Mercury can be excreted in feaces and urine, with a half-life of about 2 months. In contrast to inorganic mercury, 90% of the methylmercury is eliminated from the body in the feces, and less than 10% is in the urine, with a half-life of 45-70 days (Bridges and Zalpus, 2005).
2.5 Routes of Exposure
The following is a preview of major health problems in cosmetology arising from inhalation, skin contact, skin absorption, and long term exposure.
• Inhalation: Particulates and solvents can be inhaled from the use of hairsprays (and other aerosol products), from the solvents and dusts from artificial nail preparations, or from the asbestos in some hair dryers. These exposures can lead to pulmonary and respiratory abnormalities; even cosmetologists with only a few years of exposure have shown early signs of chronic obstructive lung disease which appears as a reduction in the functional volume of the lung. One may wish to consider having a lung function evaluated with inhalation testing. Possible thesaurosis due to aerosol product use has been linked to an accumulation of inhaled non-biodegradable polymers, especially PVP (polyvinylpyrrolidone) found in many hairsprays. Usually these lesions lessen when exposure is discontinued, but accumulation of these chemicals in the lower lung can result in alveolar-capillary-block syndrome, a condition in which the oxygen and carbon dioxide exchange is impaired between the lungs and blood. Propellants, solvents, or solvent carriers such as fluorocarbons (Freon II), methylene chloride, isobutane, propane and ethanol have been linked to a variety of adverse health problems. Because of the close contact between the air sacs of the lungs and the bloodstream, these chemicals enter the blood through inhalation and are carried throughout the body to cause effects on other body systems. Moreover, hydrocarbon propellants and solvents are highly flammable and can cause a blowtorch effect if ignited (Nellie, 1987).
• Skin Contact: Hairdressers tend to have a high rate of nickel allergy, and experience contact sensitization to the nickel in scissors. It may be possible to avoid this by using silver-plated scissors or scissors with plastic-coated handles. Contact allergy to rubber gloves is also a frequent cause of sensitization. This appears to be due to antioxidants in the rubber and could probably be avoided by using gloves of other materials such as PVE (McCall et al., 2005).
• Skin Absorption: This is a major route of exposure for permanent hair dyes which may cause sensitization and thus allergies (skin rashes, asthma, etc.). They are considered mutagenic and thus potentially or definitely carcinogenic. Permanent wave solutions also tend to be absorbed through the skin; these are linked with sensitization and/or irritation. Another type of adverse skin effect is increased skin pigmentation (phytophorodermatitis) caused by perfumes and eau de cologne when followed by exposure to the ultraviolet light in sunlight (Kersemaekers et al., 1995).
