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Airflow obstruction has been described in workers who experienced symptoms after acute exposure to chlorine. Persistent bronchial hyperresponsiveness has also been assessed, but mainly in case studies. In this cross-sectional study, we have assessed the relationship between inhalational accidents ("puffs") involving chlorine and persistent symptoms as well as hyperresponsiveness in 239 out of 255 at-risk workers (94%). No relationship was found between persistent symptoms and the exposure variables studied. Forced vital capacity (FVC) was higher in subjects who had had no symptoms after a "puff", compared with those who had experienced mild symptoms. Forced expiratory volume in one second (FEV1) and FVC were significantly lower in subjects who experienced more than 10 puffs with mild symptoms than in subjects who reported no symptomatic puff. The presence of bronchial hyperresponsiveness was not related to exposure, but the methacholine dose-response slope showed a tendency to increased bronchial responsiveness with increased exposure. A significant difference was shown in subjects who experienced more than 10 puffs with mild symptoms. In this group of workers, repeated exposure to chlorine with acute respiratory symptoms was associated with a slight but significant reduction in expiratory flow rates, together with an increase in bronchial responsiveness, without long-term symptoms.

The authors describe the case of a highly stressed 36-year-old man who experienced ten or more painful episodes per year of recurrent oral-lingual herpes simplex virus 1, which were only partially responsive to acyclovir therapy for three years. A three-year diary of activities, personal stresses, concurrent infections, local trauma, and other possible psychogenic, somatogenic, and environmental events was used systematically to attempt to pair the stresses with the recurrent herpes episodes. Chlorinated swimming pool water seems to have been the triggering agent of the recurrent herpes simplex virus 1 episodes due to its temporal correlation and the greater than twenty-four-month asymptomatic period after the patient discontinued swimming in chlorinated water, but continued to swim in fresh and salt water, along with his normal pursuit of all other activities and habits.

This paper evaluates the performance of four variable selection methods suitable for case-control studies. Two of the methods are logistic regression and the rank transformed version of it which uses the ranks of the explanatory variables in place of the original observations. The third method is based on Kendall's tau b correlations. I propose a fourth method, a sign score regression model to select variables. To evaluate these four methods, I generate many data sets for a case group and a control group with the use of several different distributions and covariance matrices. I evaluate the methods on their ability to select correctly the variables related to case-control status while not selecting the unrelated variables. Using this criterion, the sign score regression method and the tau b method are more effective than the other two methods with uncorrelated or weakly correlated variables. The sign score regression method is more effective than the tau b method for all simulations that use normal variables and for some that use log-normal variables. Overall, the sign score regression method is the most effective variable selection method for data sets that have low or moderate correlations between variables.

Chlorine, commonly used to disinfect drinking water, produces by-products known from animal studies to be carcinogenic and mutagenic. Most epidemiological studies into the possible association between chlorination by-products in drinking water and cancer have been ecological in nature, or have relied on case-control designs based on death certificates. Interpretation of results arising from these studies is limited. Individual levels of toxicant exposure and many potential confounders and effect modifiers are unable to be accounted for in the analyses. At best, these studies generate hypotheses that require more definitive investigation. Misclassification of individuals based on inaccurate assessment of the level of exposure is probable. The few analytic studies able to overcome or minimise these problems suggest a clear link between exposure to chlorinated drinking water and the development of urinary bladder cancer. They also suggest a possible link with rectal cancer. However, these studies have classified subjects by exposure to chlorinated drinking water, rather than to levels of chlorine and its by-products in drinking water. To date, the link between levels of chlorine and its by-products in water, levels of consumption and cancer has not been made. Information on the levels of chlorine and some by-products is available in many water jurisdictions in Australia. Further, epidemiological methods can be employed to quantify water consumption. Case-control studies linking these parameters would help us to understand the magnitude of the risk to human populations and provide a basis to investigate mechanisms for risk reduction.

Studies were done to examine the comparability of Colisure (TM) and accepted reference methods to detect low numbers of total coliform bacteria and E.coli subjected to chlorine stress. Colisure (TM) is a medium designed to concurrently detect coliform bacteria and E.coli in drinking water by the specific action of beta-galactosidase (total coliforms) and beta-glucuronidase (E.coli). The methods used to compare the performance of various media followed a protocol established by the USEPA. Samples (31) of sewage from six different regions of the US were treated with sufficient concentrations of chlorine (1.2-2.5mg/l) to reduce viability 1-3 logs (39% average injury) and diluted with drinking water to achieve ca. 3 viable coliforms/100ml. The mean log reductions in viable bacteria, determined with various media following disinfection of the 31 samples were: mEndo = 1.87 (TC), Colisure (TM) = 1.55 (TC), mTec = 3.63 (E.coli) and Colisure (TM) = 2.01 (E.coli). When Colisure (TM) was compared with accepted methods to detect total coliforms in the dilute, disinfected samples, Colisure (TM) yielded results that were 1.6 times greater than LTB confirmed in BGLB at 28h. Colisure (TM) also detected 1.7 times greater levels of E.coli than LTB confirmed in EC/MUG at 28h. Sensitivity and specificity of Colisure (TM) were between 96 and 100% when positive and negative tests were verified. These findings indicate that Colisure (TM) is superior to certain accepted reference methods in the detection of chlorine-injured coliforms and E.coli under conditions that resemble contaminated drinking water.

Two patients were admitted to the hospital emergency room in respiratory distress after an accidental explosion involving chlorinating agents for the swimming pool. The two primary agents involved were calcium hypochlorite and trichloro-s-triazinetrione; both are commonly used chlorinating agents. These chemicals were tested in a bomb apparatus measuring temperature and gas production. Combining the two chlorinators at 2, 6, 12, or 18 g of each produced a progressive increase in gas production from 234 to 1422 mL. The temperature increased from 30 degrees C at 2 g to 63 degrees C at 18 g. The time to complete the reaction decreased from 6.2 minutes at 2 g to 3.8 minutes at 18 g. The third run at the 18 g level resulted in an explosion. The results indicate that gas generation is dependent on both products. The addition of organic material was abandoned because of the explosive nature of the reaction. The amount of calcium hypochlorite primarily determines the rate of reaction and heat generation. Appropriate emergency action and treatment for chlorine gas is discussed.

The reactive airways dysfunction syndrome (RADS) occurs as a persistent bronchial hyper-reactivity with asthmatic-type dyspnoea and occurs after a single and massive inhalation of irritant gases, smoke or vapours, in subjects who had previously had no respiratory disease. We report six cases in patients without any previous asthmatic history or history of atopy who had developed RADS after being exposed to different irritants. The symptoms evolved over 5-84 months after the initial accident. Only moderate airflow obstruction was found, but all subjects had bronchial hyper-reactivity to methacholine. A bronchial biopsy was performed in a patient and this showed moderate sub-epithelial mononuclear inflammatory infiltrate. A specific feature of this syndrome is the facility to inaugurate a susceptibility to asthma after the initial accident and for this to progress of its own accord with secondary aggravation, even in the absence of new exposure to the irritating agent. Its frequency is probably under-estimated because it remains little known in France. It is very important both to recognise and notify inhalational accidents at work to be able, should the nedd arise, to identify the worker and to enable a move to a different job if necessary.

A case of tooth erosion due to prolonged exposure to acidic pool water has been presented. Dentists and swimmers must be aware of the detrimental dental effects associated with prolonged exposure to improperly maintained pool water, and what measures can be taken to prevent such effects.

A retrospective exposure assessment study in the automotive parts industry conducted in conjunction with a cancer mortality and respiratory morbidity study [Kennedy et al. (1989): Am J Ind Med 15:627-641; Eisen et al. (1992): Am J Ind Med 22:809-824; Tolbert et al. (1992): Scand J Work Environ Health 18:351-360] describes exposure to different types of machining fluids and selected components that may contribute to the conditions investigated. A dataset of 394 industrial hygiene measurements made between 1958 and 1987 was used to estimate past machining fluid levels using a linear statistical model. The effects of different plants, machining fluid types, machining operations, and time periods were examined in the model. Separate analyses examined the effects of different sampling and analysis methods and other measurement variables. Machining fluid levels prior to 1970 were generally two to five times higher than subsequent measurements. The arithmetic mean exposure of all measurements taken before 1970 was 5.42 mg/m3. Arithmetic means for different subgroups ranged from 0.59 to 20.28 mg/m3, depending upon plant, machining fluid, and operation. The arithmetic mean exposure after 1980 was 1.82 mg/m3 with subgroups ranging from 0.45 to 2.79 mg/m3. Changes in exposure levels generally corresponded with reported changes in plant environments such as installation of enclosures and local exhaust ventilation on machines.

Recreational exposure to the sun may not explain fully current trends in melanoma incidence. The hypothesis was examined whether carcinogens in water play a role in the development of cutaneous melanoma. In a case-control study, 128 melanoma patients and 168 patients with other types of malignancy completed a detailed questionnaire on aquatic leisure time activities. All relative risk estimates were adjusted for age, gender, educational level, pigmentation characteristics, and exposure to sun habits. Regular swimming during the summer months in swimming pools and in open waters such as rivers and seas before the age of 15 years, was associated with odds ratios of 2.20 (95% confidence interval (CI), 1.05-4.62) and 2.41 (95% CI, 1.04-5.58), respectively, compared with no swimming at all or swimming in relatively unpolluted waters, such as lakes and fens. Melanoma patients learned to swim at a younger age; compared with those who never learned to swim or who learned to swim after the age of 12 years, the odds ratio was 1.87 (95% CI, 0.91-3.78) for those who learned to swim at ages 9-12 years, and 2.22 (95% CI, 1.16-4.26) for those who learned to swim before 9 years of age. Compared with persons who had no swimming certificates, an odds ratio of 1.25 (95% CI, 0.71-2.23) was found for persons with one or two certificates, and an odds ratio of 2.96 (95% CI, 1.25-6.96) for persons with three or more certificates. The positive association between a history of swimming and melanoma risk suggests that carcinogenic agents in water, possibly chlorination by products, play a role in melanoma aetiology.

Repeated exposure to chlorine in pulp mills and paper can induce persistent asthma-like symptoms such as bronchial hyperresponsiveness and variable changes in airway caliber. The long-term time course of bronchial hyperresponsiveness has not been examined. We studied 20 of 29 subjects (69% participation rate) who demonstrated bronchial hyperresponsiveness to methacholine when they were first assessed, 18 to 24 mo after repeatedly inhaling "puffs" of high concentrations of chlorine in a paper mill over a 3-mo period. Each subject answered a respiratory questionnaire and underwent spirometry and a methacholine inhalation test 12 mo after the initial survey, 30 to 36 mo after the chlorine inhalations. Three subjects required inhaled steroids at the time of the initial survey and three at the time of the second, including two who carried on using these preparations. Only one subject changed smoking habits. There were no significant overall changes in FEV1 on the two occasions, nine subjects having a FEV1 < 80% on the first occasion and eight on the second. Six of the 18 subjects (33%) who underwent a methacholine inhalation test on both occasions had significantly improved PC20 results, including five for whom the PC20 value was within the normal range. All six subjects had normal FEV1 values on both assessments. Although changes in spirometry induced by repeated exposure to chlorine seem to persist, bronchial hyperresponsiveness can improve significantly in those with normal airway caliber. This suggests that less pronounced bronchial alterations induced by repeated exposures to chlorine may be reversible.

A cohort mortality study was conducted among 9028 (3042 women, 5986 men) workers potentially exposed to chlorinated naphthalenes (chloracnegens structurally similar to dioxins) and asbestos in the manufacture of Navy cable during World War II. Based on mortality through December 31, 1985, standardized mortality ratios (SMRs) for all cancers was 1.03 in women (95% confidence interval [CI] = 0.9 to 1.17) and 1.18 in men (95% CI = 1.10 to 1.26). There were no significant elevations in causes of death hypothesized a prior to be associated with chlorinated naphthalene exposure (malignant neoplasms [MN] of connective tissue, liver, and lymphatic and hematopoietic organs). An excess of MN of the connective tissue was suggested for workers with over 1 year of exposure and 25 years of latency (SMR = 3.54; 95% CI = 0.97 to 9.07). Among cancer sites not hypothesized to be related a priori, three showed concordant excesses among both genders (MN of stomach; rectum; and trachea, bronchus, and lung). No significant elevations occurred in hormonally related cancers among women. Cancer mortality among 460 individuals with chloracne (431 men, 29 women) was similar to that of the entire cohort, although the chloracne subcohort showed significant excesses in two rare causes of death (MN of esophagus, SMR = 3.26; "benign and unspecified neoplasms," SMR = 4.93). Use of county referent rates decreased SMRs for stomach, rectal, and buccal cavity cancer, suggesting a role for nonoccupational risk factors. It is difficult to draw conclusions about carcinogenicity of chlorinated naphthalenes because of study limitations, most importantly, concomitant asbestos exposure and the relatively short duration of exposure to chlorinated naphthalenes among most of the cohort.

Objectives: The purpose of this study was to investigate the relationship between exposure to mutagenic drinking water and cancers of the gastrointestinal and urinary tract., Methods: Past exposure to drinking water mutagenicity was assessed in 56 Finnish municipalities for the years 1955 and 1970. The cases of bladder, kidney, stomach, colon, and rectum cancers were derived from two periods (1967 to 1976 and 1977 to 1986). Age, sex, social class, urban living, and time period were taken into account in the Poisson regression analysis., Results: Statistically significant exposure-response association was observed between exposure and incidence of bladder, kidney, and stomach cancers. In an ordinary municipality using chlorinated surface water, this exposure would indicate a relative risk of 1.2 for bladder cancer and of 1.2 to 1.4 for kidney cancer compared with municipalities where nonmutagenic drinking water was consumed., Conclusions: The acidic mutagenic compounds present in drinking water may play a role in the etiology of kidney and bladder cancers, but, because the results are based on aggregate data, they should be interpreted with caution.

A pilot study addressed potential effects of long-term exposure to chlorination products in swimming pools. The indicator compound chloroform was detectable in blood from competitive swimmers in an indoor pool (mean = 0.89 +/- 0.34 microgram/l; n = 10), but not in outdoor pool swimmers. No hepatotoxic effect was indicated by serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT) or gamma-glutamyl transpeptidase (gamma-GT) enzyme levels. beta-2-microglobulin, an indicator of renal damage, was significantly elevated in urine samples of the slightly, but significantly, younger indoor swimmers. The precise ratio between these 2 possible causes, age and chloroform exposure, as well as the mechanism of the former, remain to be elucidated.

Chlorine gas inhalation can lead to temporary mucous membrane irritation, pulmonary edema, and transient bronchospasm. Existence of respiratory sequelae is debated. We report a case of asthma, persisting 2 years after the inhalation of a mixture of sodium hypochlorite and hydrochloric acid. Bronchial histologic findings and transmission electron microscopy examinations showed uncommon abnormalities supporting irritation for cause of this nonimmunologic asthma.

Exposures to chlorination by-products (CBP) within public water supplies are multiroute in water. Cold water is primarily used for ingestion while a mixture of cold water and hot water is used for showering, bathing others, dish washing, etc. These latter two activities result in inhalation and dermal exposure. Heating water was observed to change the concentration of various CBP. An increase in the trihalomethanes (THM) concentrations and a decrease in the haloacetonitriles and halopropanones concentration, though an initial rise in the concentration of dichloropropanone, were observed. The extent of the increase in the THM is dependent on the chlorine residual present. Therefore, estimates of total exposure to CBP from public water supplies need to consider any changes in their concentration with different water uses. The overall THM exposures calculated using the THM concentration in heated water were 50% higher than those calculated using the THM concentration present in cold water. The estimated lifetime cancer risk associated with exposure to THM in water during the shower is therefore underestimated by 50% if the concentration of THM in cold water is used in the risk assessment.

Epidemiological studies report associations between cancer mortality and type of drinking water source. Different studies appeared to lend some support to the hypothesis that surface waters contain higher levels of human carcinogens than groundwater sources. The possible contaminants that might play such a role are the halogenated organic compounds produced by the chemical reaction between organic materials in water and chlorine used for disinfection. Chlorine reacts with naturally occurring organic compounds in the water to form haloforms. Valencia Province of Spain relies almost exclusively on groundwater for its public drinking water, but the city and surrounding urban areas rely on superficial water. The chlorination used in the superficial water includes several phases: prechlorination, coagulation, filtration, and, finally, postchlorination, which shows the possible formation of organohalogenated compounds. To find an association between stomach and bladder cancer mortality with the type of water source, we studied 261 municipalities of Valencia Province. We calculated sex-specific standardized mortality ratios for deaths occurring between the 1985 to 1989 (census statistics), and we carried out a relative-risk calculation associated with the differences between superficial and groundwater supplies.

A population-based case-control study of bladder cancer and drinking water disinfection methods was conducted during 1990-1991 in Colorado. Surface water in Colorado has historically been disinfected with chlorine (chlorination) or with a combination of chlorine and ammonia (chloramination). A total of 327 histologically verified bladder cancer cases were frequency matched by age and sex to 261 other-cancer controls. Subjects were interviewed by telephone about residential and water source histories. This information was linked to data from water utility and Colorado Department of Health records to create a drinking water exposure profile. After adjustment for cigarette smoking, tap water and coffee consumption, and medical history factors by logistic regression, years of exposure to chlorinated surface water were significantly associated with risk for bladder cancer (p = 0.0007). The odds ratio for bladder cancer increased for longer durations of exposure to a level of 1.8 (95% confidence interval 1.1-2.9) for more than 30 years of exposure to chlorinated surface water compared with no exposure. The increased bladder cancer risk was similar for males and females and for nonsmokers and smokers. Levels of total trihalomethanes, nitrates, and residual chlorine were not associated with bladder cancer risk after controlling for years of exposure to chlorinated water.

Animal studies and a single human epidemiological study have suggested that chlorine in drinking water may raise the level of blood cholesterol. The purpose of this study was to determine whether a 4-week exposure to drinking water chlorine (1.5 L per day) at a concentration of 20 ppm (ppm = mg/L) under controlled conditions would alter circulating parameters of lipid metabolism in healthy humans. Thirty men and thirty women each completed an 8-week protocol during which diet (600 mg cholesterol per day, 40% calories as fat) and other factors known to affect lipid metabolism were controlled. For the first 4 weeks of the protocol, all subjects consumed distilled water. For the second 4 weeks, half of the subjects were assigned randomly to drink 1.5 L per day of chlorinated water (20 ppm), while the others continued drinking distilled water. Four blood samples were collected from each subject at the end of each 4-week study period. Compared to the control group, those subjects given chlorine showed no significant changes in total plasma cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol, or apolipoproteins A1, A2, or B. There was a trend toward low serum thyroxine and triiodothyronine levels in men given chlorine, though thyroid-stimulating hormone levels were unchanged. This trend, if real, was not clinically significant. Thus, short-term exposure to chlorinated drinking water at 20 ppm appears to have no significant impact on parameters of lipid or thyroid metabolism in healthy humans.

We report the case of an 11-yr-old boy who developed a non-cardiogenic pulmonary edema following inhalation of chlorine gas at a swimming pool. Rapid clinical improvement was noted after i.v. administration of morphine.

Disinfectants called by producers stabilized chlorine dioxide (ClO2) are most often composed of sodium carbonate aqueous solution and ClO2. Stability is due to sodium chlorate which is produced under these conditions. Solutions of active ClO2 obtained through acidification of the preparation with citric acid and an appropriate water dilution are used in disinfection. Then, free ClO2 becomes an active disinfecting factor--a gas of strong irritative properties. During a disinfecting process the gas is liberated from the solution due to pulverization and dryness of disinfected objects. The study indicated that the safety of work with disinfectants requires mechanical ventilation of working premises. The transformation of stabile ClO2 into an active form should be induced by adding an appropriate volume of the stabilising preparation to citric acid solution. Such a procedure assures that a maximum of gaseous ClO2 will be retained in water.

Several factors have stimulated interest in recently developed substrate specific media for the detection of coliform bacteria in water. This study compared the performance of Colisure (TM) (Millipore), ColiLert (TM) (Environetics) and ColiQuick (TM) (Hach) with accepted membrane filtration and MPN methodologies for the enumeration of total coliforms and E. coli in chlorinated water. The performance of all three media was compared, in MPN configuration, with LTB/MPN (confirmed) using a variety of drinking and source water samples, both with and without chlorination. The Cochran-Mantel-Haenszel test yielded statistical correlations between results obtained with each of the three new enzyme detection media and accepted reference methods for the detection of low numbers of total coliforms. Another series of tests compared the performance of Colisure with accepted methods (LTB/MPN confirmed with BGLB and EC-MUG) in the detection of total coliforms and E. coli in sewage-spiked samples simulating contaminated drinking water, using an USEPA/AWWA test protocol. The results demonstrated that Colisure detected these indicator bacteria with greater sensitivity than the accepted methods and that this difference increased between 24 and 28 hours of incubation. The results of this study collectively support the validity of the new enzyme detection method for the detection of low levels of coliform bacteria and E. coli in source water and contaminated drinking water.

Six members of the International Society for Environmental Epidemiology provide a discussion of the presentations of the authors of six studies dealing with the potential chronic disease side effects of water disinfection. This symposium, which was jointly sponsored by the Society and the United States Environmental Protection Agency (EPA) also involved state epidemiologists and engineers from state drinking water programs. This article summarizes the results of the studies and the comments about them. There was a general consensus that the recent EPA sponsored studies of cancer endpoints have strengthened the evidence linking bladder cancer with long term exposure to chlorinated drinking water. The evidence for links with colon cancer is not convincing and that for serum lipid changes is quite weak. Any risks, if real, are low when compared to the risk of infection from not disinfecting water. This is particularly true for small water systems where chlorination may be the only practical option.

A case-control study was done to assess a potential association between drinking water and pancreatic cancer in Washington County, Maryland. Cases of pancreatic cancer occurring from 1975 through 1989 were identified from the cancer registry. Controls were selected from the private 1975 census of Washington County. There were 101 cases and 206 controls. Chlorinated municipal water was used as a source of drinking water by 79% of cases and 63% of controls, yielding a significant odds ratio of 2.2. Adjustment for age and smoking had almost no effect on the risk, although both age and smoking were independently associated with an increased risk of pancreatic cancer. Although these findings must be interpreted with caution because of limitations in exposure assessment, these results have implications for the prevention of pancreatic cancer because chlorination of water is so widely practiced.

Objectives: Individual epidemiological investigations into the association between chlorination by-products in drinking water and cancer have been suggestive but inconclusive. Enough studies exist to provide the basis for a meaningful meta-analysis., Methods: An extensive literature search was performed to identify pertinent case-control studies and cohort studies. Consumption of chlorinated water, surface water, or water with high levels of chloroform was used as a surrogate for exposure to chlorination by-products. Relative risk estimates were abstracted from the individual studies and pooled., Results: A simple meta-analysis of all cancer sites yielded a relative risk estimate for exposure to chlorination by-products of 1.15 (95% CI: 1.09, 1.20). Pooled relative risk estimates for organ-specific neoplasms were 1.21 (95% CI: 1.09, 1.34) for bladder cancer and 1.38 (95% CI: 1.01, 1.87) for rectal cancer. When studies that adjusted for potential confounders were pooled separately, estimates of relative risks did not change substantially., Conclusions: The results of this meta-analysis suggest a positive association between consumption of chlorination by-products in drinking water and bladder and rectal cancer in humans.

This case-control study evaluated the relationship between lung cancer and occupational factors among employees at a dye and resin manufacturing plant. The study included 51 lung cancer cases and 102 controls who were members of a cohort of workers investigated in a previous retrospective follow-up study. Information on area of employment and on potential exposure to certain chemicals was obtained from plant personnel and medical records and from interviews with long-term employees. Information on potential confounders, including cigarette smoking, was obtained by interviewing study subjects or their next-of-kin. The odds ratio (OR) for heavy smokers compared with light or nonsmokers was 5.9 (95% confidence interval (CI) = 2.4-15). An elevated OR for lung cancer was observed for subjects who worked in the anthraquinone dye and epichlorohydrin manufacturing area of the plant (OR = 2.4; 95% CI = 1.1-5.2) and for employees who were seen at the plant infirmary for acute exposure to chlorine (OR, adjusted for smoking = 27; 95% CI = 3.5-205). Pipefitters employed at the plant for five or more years also had an elevated OR (3.3; 95% CI = 0.8-14).

Fifty chemically sensitive patients with vascular, asthmatic and arthritic signs, ranging in age from 21 to 61, were exposed to double-blind challenges of ambient doses of inhaled toxic chemicals in a specially designed booth in an Environmental Control Unit (ECU). Primary signs and symptoms were recorded before and after challenge with five chemicals and three placebos. Inhaled challenges included phenol (less than .0025 ppm), petroleum-derived ethyl alcohol (less than .5 ppm), formaldehyde (less than .2 ppm), chlorine (less than .3 ppm), and pesticide (2, 3,-D at less than .0034 ppm). Placebos were water or saline. A set on testing criteria were evaluated for maximizing the likelihood of well-defined, reproducible information from these ambient-dose double-blind challenges. For best results, these testing criteria include: Before testing, the patient must be housed in a chemically less polluted environment. The individual must have been de-adapted to food, air, and water pollutants by means of a water fat for three to four days. At the time of the challenge, the patient must be on food and water previously determined to be safe. An enclosed non-pulluted challenge booth must be used for these chemical exposures. Sign and symptom scores appropriate for that patient must be recorded, before and after challenge. Appropriate doses of the chemical in question (determined by air concentration and length of exposure) are necessary to investigate a particular problem. The conclusion of the study is that in these patients, chemical sensitivity clearly does exist (pulse rate differences between positive responses and placebo - p .001).(ABSTRACT TRUNCATED AT 250 WORDS)

While chlorine gas inhalation has previously been reported to cause temporary mucous membrane irritation, acute pneumonitis, pulmonary edema, and transient bronchospasm, there is controversy about the existence of long-term pulmonary sequelae. We report the case of a 25-year-old man in whom chronic, recurrent asthma developed after exposure to a chlorine gas leak in an enclosed space. His course since the exposure has been notable for frequent exacerbations necessitating chronic corticosteroid therapy and multiple hospitalizations. To our knowledge, the persistence of symptoms years after the exposure is unique in the literature.

Workers in pulpmills can be exposed to a multitude of gases hazardous to respiratory function, the most common of which is chlorine gas. First-aid reports of acute gas overexposure incidents ("gassings") over an 8 year period were used to generate exposure data on a group of pulpmill workers whose respiratory function had been studied cross-sectionally in 1981 and 1988. Three hundred forty-eight incidents representing 174 workers were identified, 78% of these being treated solely by the first-aid attendant with the administration of O2 and cough suppression medication. Among 316 workers tested during a 1988 respiratory health survey, 78 had at least one chlorine or chlorine dioxide "gassing" incident. There was a significant decrease in the FEV1/FVC ratio (p less than .05) as well as increased risk for workplace associated chest symptoms in this group with at least one "gassing" incident. In an age- and smoking-matched analysis, among workers tested both in 1981 and 1988, there was a greater decline in FEV2/FVC ratio and MMF (p less than .05) in the "gassed" group than in the nonexposed group over the 7 year period of observation. These results emphasize the need for worker protection against accidental chlorine gas exposures.

The long-term consequences of accidental chlorine gas exposure have been investigated, mainly in the community setting, among persons exposed as a result of a nearby chlorine spill. This circumstance is not analogous to the more frequent chlorine or chlorine dioxide gas overexposures that occur commonly in pulpmills over a background of a low level of gas exposure. To investigate the respiratory health consequences of these accidental exposures ("chlorine gassing") in the industrial setting, we carried out a cross-sectional respiratory health survey among workers at a British Columbia coastal pulpmill and a nearby rail maintenance yard. A greater proportion of pulpmill workers were unavailable for study because of illness (10.5% versus 2.4% in the railyard, p less than 0.01). Procedures involved simple spirometry, respiratory symptom assessment, and measurement of average levels of air contaminants. Average chlorine levels in the pulpmill were below 1 ppm; however, 60% of the pulpmill workers reported one or more accidental "chlorine gassing" incidents. Pulpmill workers who reported being "gassed" were significantly more likely to report wheezing on occasion than were other pulpmill workers and railyard workers (rate for these three groups: nonsmokers: 8, 2, 1%; ex-smokers: 17, 11, 7%; current smokers: 42, 21, 19%; p less than 0.05). No significant lung function differences were found between the overall pulpmill group and the railyard workers; however, nonsmoking and formerly smoking pulpmill workers who reported being "gassed" had significantly lower average midmaximal flow rate and FEV1/FVC ratio than did their counterparts in the remainder of the pulpmill population (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)