Chloroform is a known contaminant of chlorinated drinking water and of swimming pool water disinfected with chlorine or one of its derivatives. Few data exist regarding the importance of dermal and inhalation exposure routes to the chloroform body burden resulting from domestic and recreational use of chlorinated water. In our experimental study involving 11 male swimmers, we quantified the body burden resulting from exposure to various concentrations of chloroform in water and air of an indoor swimming pool, during a daily 55-min exercise period. From the first to the sixth exercise period, CHCl3 mean concentration in water was increased from 159 micrograms/l to 553 micrograms/l. Corresponding mean air CHCl3 level ranged from 597 ppb to 1630 ppb. To dissociate the dermal exposure route from that of inhalation, swimmers used scuba tanks during an additional exercise period. Chloroform concentrations were measured in alveolar air before and after each exercise period, as well as after 35 min of physical activity. Chloroform levels in water and air were measured every 10 min. We examined the relationship between alveolar air concentration (a measure of body burden) at 35 and 55 min and environmental chloroform concentrations by using multiple regression models. The natural logarithm of alveolar air concentration was strongly correlated with aqueous chloroform concentration both at 35 (p2 < 0.001, r2 = 0.75) and 55 min (p < 0.001, r2 = 0.86). The relationship with air concentrations was also statistically significant (35 min: p < 0.001, r2 = 0.58, 55 min: p < 0.001, r2 = 0.63).(ABSTRACT TRUNCATED AT 250 WORDS)

Objective-The prevalence of symptoms associated with the sick building syndrome (SBS) has recently been shown to decrease by 40% to 50% among office workers six months after they were exposed to a building with an improved ventilation system. The objective of the present study was to find whether the decrease in the prevalence of symptoms was maintained three years later. Methods-Workers from the same organisation occupied five buildings in 1991 and moved during that year to a single building with an improved ventilation system. All buildings had sealed windows with mechanical ventilation, air conditioning, and humidification. Workers completed a self administered questionnaire during normal working hours in February 1991 before moving, in February 1992 six months after moving, and in February 1995, three years after moving. The questionnaire encompassed symptoms of the eyes, nose and throat, respiratory system, skin, fatigue, and headache, as well as difficulty concentrating, personal, psychosocial, and workstation factors. During normal office hours of the same weeks, environmental variables were measured. Results-The study population comprised 1390 workers in 1991, 1371 in 1993, and 1359 in 1995, which represents 80% of the population eligible each year. The prevalence ofmost symptoms decreased by 40% to 50% in 1992 compared with 1991. This was similar in 1995. These findings were significant and remained generally similar after controlling for personal, psychosocial, and work related factors. Conclusion-In this study, the decrease of 40% to 50% in the prevalence of most symptoms investigated six months after workers were exposed to a new building with an improved ventilation system was maintained three years later. (SBS).' This typically involves symptoms from the central nervous system (headache, fatigue, and difficulty concentrating), and from mucous membranes (nose, throat, and airways), eyes, and skin.' Studies selected without regard to symptom complaints reported a prevalence of 20% or more of at least one work related symptom (usually improving when away from work) among workers occupying office buildings.2AAlthough the mechanisms involved in the production of symptoms are largely unknown, in many studies, several factors have been associated with an increased prevalence of symptoms. Personal (allergies and asthma, female sex), psychosocial (stress and dissatisfaction at work), and workstation factors (presence of carpet, time spent at a video display terminal, lighting, noise, comfort) have been associated with an increased prevalence of symptoms.5 Building and ventilation factors are thought to influence the prevalence of symptoms associated with the SBS. In a reanalysis of six epidemiological studies,6 it was shown that the prevalence of symptoms was consistently two to three times greater in buildings with mechanical ventilation and air conditioning than in buildings with natural or simple mechanical ventilation. In these studies, the presence of sealed windows, in 47 of 48 buildings, was...

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Objective-To find if the prevalence of symptoms associated with sick building syndrome decreased among office workers after moving to a building with improved ventilation (after controlling for potential confounders). (23%). These findings were all significant and remained generally similar after controlling for personal, psychosocial, and work related factors. Furthermore, more than 60% of workers symptomatic in 1991 were asymptomatic in 1992 for all types of symptoms. In contrast, less than 15% of workers were asymptomatic in 1991 but symptomatic in 1992 for all types of symptoms. Conclusion-In this study, the prevalence of most symptoms usually associated with the sick building syndrome decreased by 40% to 50% after workers were transferred to a building with an improved ventilation system. The results show that it is possible to diminish the prevalence of symptoms associated with the sick building syndrome among office workers occupying a building with mechanical ventilation, air conditioning, and sealed windows. Keywords: sick building syndrome; office workers; indoor air quality As defined by the World Health Organisation, the sick building syndrome is characterised by an excessive prevalence of irritative symptoms of the skin and the mucous membranes and other symptoms including fatigue, headache, and difficulty concentrating in the people occupying a building.' Overall evidence suggests that these symptoms are relatively common among office workers. Studies on workers in buildings selected without regard to complaints about symptoms reported a prevalence of more than 20% of at least one work related symptom (usually defined as a symptom that improves when away from work).2 4 Such symptoms could have an impact on a worker's productivity. 6 A study conducted in a stratified random sample of office workers in the United States showed that at least 20% reported a decrease in work performance as a consequence of their symptoms.7 MethodsAlthough specific aetiological exposures have not been shown to be the cause of these symptoms, in many studies, several factors have been associated with an increased prevalence of symptoms. In a reanalysis of six epidemiological studies,8 it was shown that the prevalence of symptoms was consistently two to three times greater in buildings with mechanical ventilation and air conditioning than in buildings with natural or simple mechanical ventilation. In these six studies, the presence of sealed windows was a usual feature of buildings with mechanical ventilation and air conditioning, being present in 47 of 48

We evaluated alveolar carbon monoxide (CO) levels of 122 male, adult hockey players active in recreational leagues of the Quebec City region (Canada), before and after 10 weekly 90-minute games in 10 different rinks. We also determined exposure by quantifying the average CO level in the rink during the games. Other variables documented included age, pulmonary function, aerobic capacity, and smoking status. Environmental concentrations varied from 1.6 to 131.5 parts per million (ppm). We examined the absorption/exposure relationship using a simple linear regression