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Monday, 21 March 2011 15:29

Health Problems and Disease Patterns

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Teachers comprise a large and growing segment of the workforce in many countries. For example, over 4.2 million workers were classified as preschool through high school teachers in the United States in 1992. In addition to classroom teachers, other professional and technical workers are employed by schools, including custodial and maintenance workers, nurses, food service workers and mechanics.

Teaching has not traditionally been regarded as an occupation that entails exposure to hazardous substances. Consequently, few studies of occupationally related health problems have been carried out. Nevertheless, school teachers and other school personnel may be exposed to a wide variety of recognized physical, chemical, biological and other occupational hazards.

Indoor air pollution is an important cause of acute illnesses in teachers. A major source of indoor air pollution is inadequate maintenance of heating, ventilation and air conditioning systems (HVAC). Contamination of HVAC systems can cause acute respiratory and dermatological illnesses. Newly constructed or renovated school buildings release chemicals, dusts and vapours into the air. Other sources of indoor air pollution are roofing, insulation, carpets, drapes and furniture, paint, caulk and other chemicals. Unrepaired water damage, as from roof leakage, can lead to the growth of micro-organisms in building materials and ventilation systems and the release of bioaerosols that affect the respiratory systems of teachers and students alike. Contamination of school buildings by micro-organisms can cause severe health conditions such as pneumonia, upper respiratory infections, asthma and allergic rhinitis.

Teachers who specialize in certain technical fields may be exposed to specific occupational hazards. For example, arts and craft teachers frequently encounter a variety of chemicals, including organic solvents, pigments and dyes, metals and metal compounds, minerals and plastics (Rossol 1990). Other art materials cause allergic reactions. Exposure to many of these materials is strictly regulated in the industrial workplace but not in the classroom. Chemistry and biology teachers work with toxic chemicals such as formaldehyde and other biohazards in school laboratories. Shop teachers work in dusty environments and may be exposed to high levels of wood dust and cleaning materials, as well as high noise levels.

Teaching is an occupation that is often characterized by a high degree of stress, absenteeism and burnout. There are many sources of teacher stress, which may vary with grade level. They include administrative and curriculum concerns, career advancement, student motivation, class size, role conflict and job security. Stress may also arise from dealing with children’s misbehaviours and possibly violence and weapons in schools, in addition to physical or environmental hazards such as noise. For example, desirable classroom sound levels are 40 to 50 decibels (dB) (Silverstone 1981), whereas in one survey of several schools, classroom sound levels averaged between 59 and 65 dB (Orloske and Leddo 1981). Teachers who are employed in second jobs after work or during the summer may be exposed to additional workplace hazards that can affect performance and health. The fact that the majority of teachers are women (three-fourths of all teachers in the United States are women) raises the question of how the dual role of worker and mother may affect women’s health. However, despite perceived high levels of stress, the rate of cardiovascular disease mortality in teachers was lower than in other occupations in several studies (Herloff and Jarvholm 1989), which could be due to lower prevalence of smoking and less consumption of alcohol.

There is a growing concern that some school environments may include cancer-causing materials such as asbestos, electromagnetic fields (EMF), lead, pesticides, radon and indoor air pollution (Regents Advisory Committee on Environmental Quality in Schools 1994). Asbestos exposure is a special concern among custodial and maintenance workers. A high prevalence of abnormalities associated with asbestos-related diseases has been documented in school custodians and maintenance employees (Anderson et al. 1992). The airborne concentration of asbestos has been reported higher in certain schools than in other buildings (Lee et al. 1992).

Some school buildings were built near high-voltage transmission power lines, which are sources of EMF. Exposure to EMF also comes from video display units or exposed wiring. Excess exposure to EMF has been linked to the incidence of leukaemia as well as breast and brain cancers in some studies (Savitz 1993). Another source of concern is exposure to pesticides that are applied to control the spread of insect and vermin populations in schools. It has been hypothesized that pesticide residues measured in adipose tissue and serum of breast cancer patients may be related to the development of this disease (Wolff et al. 1993).

The large proportion of teachers who are women has led to concerns about possible breast cancer risks. Unexplained increased breast cancer rates have been found in several studies. Using death certificates collected in 23 states in the United States between 1979 and 1987, the proportionate mortality ratios (PMRs) for breast cancer were 162 for White teachers and 214 for Black teachers (Rubin et al. 1993). Increased PMRs for breast cancer were also reported among teachers in New Jersey and in the Portland-Vancouver area (Rosenman 1994; Morton 1995). While these increases in observed rates have so far not been linked either to specific environmental factors or to other known risk factors for breast cancer, they have given rise to heightened breast cancer awareness among some teachers’ organizations, resulting in screening and early detection campaigns.



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