Biomedical subjects

David C Christiani

Publications and source records attributed to David C Christiani.

At least 127 records · Page 7Linked to original sources

PubMed2002

Pulmonary and systemic effects of zinc-containing emission particles in three rat strains: multiple exposure scenarios.

As a common component of ambient particulate matter (PM), zinc has been proposed to play a role in PM-induced adverse health effects. Although occupational exposures to high levels of zinc-fume have been associated with metal-fume fever accompanied by pulmonary inflammation and injury, the effects of PM-associated zinc are unclear. We hypothesized that an oil combustion emission PM (EPM) containing bioavailable zinc would induce pulmonary injury and systemic hematological changes attributable to the leachable zinc following acute as well as longer-term exposures in a rat strain-specific manner. In order to initially characterize the pulmonary response to EPM, male Sprague-Dawley (SD) rats were intratracheally (IT) instilled with 0.0, 0.8, 3.3, or 8.3 mg/kg EPM in saline. To further determine if the pulmonary injury was associated with the EPM leachable zinc, subsequent studies included IT instillation of SD rats with either saline, whole EPM suspension, the saline leachable fraction of EPM, the particulate fraction of EPM (all at 8.3 mg/kg, soluble Zn = 14.5 microg/mg EPM), or ZnSO(4) (0.0, 33.0, or 66.0 microg/kg Zn). Finally, to ascertain the cumulative impact of inhaled EPM in the causation of acute pulmonary and systemic effects as well as long-term fibrotic responses, we exposed three rat strains of differential susceptibility to PM. Male SD, normotensive Wistar-Kyoto (WKY), and spontaneously hypertensive (SH) rats (90 days old) were exposed nose-only to either filtered air or EPM: 2, 5, or 10 mg/m(3) (6 h/day x 4 days/week x 1 week); or 10 mg/m(3) (6 h/day x 1 day/week for 1, 4, or 16 weeks) and assessed at 2 days postexposure. IT exposures to whole EPM suspensions were associated with a dose-dependent increase in protein/albumin permeability and neutrophilic inflammation. Pulmonary protein/albumin leakage and neutrophilic inflammation caused by the leachable fraction of EPM and ZnSO(4) were comparable to the effect of whole suspension. However, protein/albumin leakage was not associated with the particulate fraction, although significant neutrophilic inflammation did occur following instillation. With EPM nose-only inhalation, acute exposures (10 mg/m(3) only) for 4 days resulted in small increases in bronchoalveolar lavage fluid (BALF) protein and n-acetyl glucosaminidase activities (approximately 50% above control). Surprisingly, unlike IT exposures, no neutrophilic influx was detectable in BALF from any of the inhalation groups. The only major effect of acute and long-term EPM inhalation was a dose- and time-dependent increase in alveolar macrophages (AM) regardless of the rat strain. Histological evidence also showed dose- and time-dependent accumulations of particle-loaded AM. Particles were also evident in interstitial spaces, and in the lung-associated lymph nodes following the inhalation exposures (SH > WKY = SD). There were strain-related differences in peripheral white blood cell counts and plasma fibrinogen with no major EPM inhalation effect. The present study demonstrated the critical differences in pulmonary responsiveness to EPM between IT and inhalation exposures, probably attributable to the dose of bioavailable zinc. EPM IT exposures, but not acute and long-term inhalation of up to 10 mg/m(3), caused neutrophilic inflammation. Inhalation exposures may result in particle accumulation and macrophage recruitment with potential strain differences in EPM clearance.

Administration, Inhalation↗

PubMed2002

The association between personal measurements of environmental exposure to particulates and heart rate variability.

BACKGROUND: Epidemiologic evidence indicates that airborne particulates are associated with mortality risk, predominately from heart disease. This may occur through changes in the cardiac autonomic nervous system, witnessed by changes in heart rate variability. METHODS: This short-term longitudinal study used continuous personal particulate matter measurements to examine the effects of exposure to particulate matter less than 2.5 microm in diameter (PM2.5) on heart rate and rate variability in 20 relatively young, healthy male workers. Continuous exposure and cardiac monitoring were performed on each subject on a nonwork day. The 5-minute standard deviation of the normal-to-normal interval was used as the main measure of heart rate variability. RESULTS: Mixed-effects regression models estimate an average 1.4% (95% confidence limits = -2.1, -0.6) decrease in the 5-minute standard deviation of the normal-to-normal interval for each 100 microg/m3 increase in the 3-hour PM2.5 moving average, and small increases in heart rate, after adjustment for potential confounding factors. Predicted effects of exposure were greatest using the 3-hour averaging interval for PM2.5 and decreased in magnitude using shorter and longer intervals. CONCLUSIONS: These results reveal an association between cardiac autonomic function and environmental PM2.5 exposure. These observed associations may result from decreased vagal or increased sympathetic tone.

Adult↗

PubMed2002

Genetic polymorphisms of MnSOD, GSTM1, GSTT1, and OGG1 in coal workers' pneumoconiosis.

Little is known about the genetic susceptibility to coal workers' pneumoconiosis (CWP). We investigated the association between genetic polymorphisms of MnSOD, GSTM1, GSTT1, or OGG1 and susceptibility to CWP. The study population was composed of 259 Chinese retired coal miners who had similar dust exposure histories. Of these, there were 99 cases with International Labor Organization chest radiologic criteria for CWP and 160 controls (with no radiologic criteria for CWP). Individual dust exposure variables were estimated from work histories, and smoking information was obtained from interviews. Polymerase chain reaction-based techniques evaluated the genotypes of all study subjects. There were no differences in genotype frequency of MnSOD, GSTM1, GSTT1, and OGG1 between miners with CWP and miners without CWP, by logistic regression analysis. Cumulative dust exposures, but not genetic polymorphisms, were associated significantly with the presence of CWP. This study illustrates the complexity of factors that may contribute to the development of CWP.

Aged↗

PubMed2002

Firefighters' blood pressure and employment status on hazardous materials teams in Massachusetts: a prospective study.

We evaluated the association between hypertension and changes in employment status in 334 hazardous materials firefighters. Firefighters were categorized by blood pressure (BP) at baseline (1996 or 1997) and subsequent follow-up examinations (1997, 1998, and 1999). They were followed up for a maximum of 4 years for possible adverse outcomes (death, placement on "injured-on-duty" status, termination of duty, resignation, retirement, or incident cardiovascular disease). In several analytic models, we found that firefighters with stage II hypertension (BP > or = 160/100 mm Hg) were consistently 2 to 3 times more likely to experience an adverse outcome compared with those with normal BP. Cox proportional-hazards regression was used to adjust for age, body mass index, smoking, cholesterol, and antihypertensive medication. In these models, the hazard ratio for stage II hypertension was 3.2 (95% confidence interval [CI], 1.50 to 7.04, P = 0.003) and for untreated stage II hypertension, it was 4.6 (95% CI, 2.08 to 10.11, P = 0.0002). Firefighters with a BP > or = 160/100 mm Hg should receive further evaluation and demonstrate improved BP control before being determined fit for duty.

Adult↗

PubMed2002

Does standing at work during pregnancy result in reduced infant birth weight?

The purpose of this study was to investigate the association between infant birth weight and standing at work during pregnancy. A total of 1222 pregnant women employed in a large petrochemical corporation in Beijing, China, were enrolled in the study, after receiving permission from the government to have a child. The subjects were followed up from that time through their entire pregnancy, for a total of up to 12 months. All subjects delivered at the company staff hospital between 1996 and 1998. Various work-related physical activities during pregnancy were assessed using a structured questionnaire, and generalized additive models (GAMs) were performed to examine their association with birth weight. Of the assessed activities, only standing was significantly associated with birth weight. After adjusting for potential confounders, maternal standing hours per day at work was found to be significantly associated with reduced birth weight (-17.7 g, P = 0.03).

Adult↗

PubMed2002

Lipid profile of firefighters over time: opportunities for prevention.

Heart disease is the primary cause of on-duty deaths in firefighters, but little is known about their lipid profile. We evaluated the lipid profile in relation to other cardiovascular disease risk factors in 321 firefighters at a baseline examination. Prospective comparisons were performed for 285 firefighters, who were enrolled in a statewide medical surveillance program, and had complete follow-up data for 4 years. The average cholesterol level in firefighters declined from 224 mg/dL at baseline (1996-1997) to 214 mg/dL at the follow-up examination (P < 0.0001). Conversely, both obesity (body mass index > or = 30; 34% versus 40%, P = 0.008) and triglycerides (> or = 200 mg/dL; 27% versus 35%, P = 0.047) increased over time. The proportion of firefighters taking lipid-lowering medications increased from 3% at baseline to 12% at follow-up (P < 0.0001). Cholesterol levels declined significantly, and treatment rates for elevated cholesterol increased over time. Despite repeated examinations, a considerable number of firefighters had persistently elevated cholesterol, and only a minority were receiving adequate treatment.

Adult↗

PubMed2002

1-hydroxypyrene as a biomarker of occupational exposure to polycyclic aromatic hydrocarbons (PAH) in boilermakers.

A repeated measures short-term prospective study was performed in boilermakers to determine occupational polycyclic aromatic hydrocarbon (PAH) exposure using the biomarker, 1-hydroxypyrene (1-OHP). Two work sites were studied; an apprentice school (metal fume exposure) and a boiler overhaul (residual oil fly ash [ROFA] and metal fume exposure). Pre- and postshift urine samples (n = 241; 41 male subjects) were analyzed for cotinine and 1-OHP. Descriptive statistics and generalized estimating equations were calculated. At the apprentice school cross-shift 1-OHP levels did not significantly differ. At the overhaul 1-OHP levels increased during the week in smokers and nonsmokers; in nonsmokers the 1-OHP level increased significantly postshift compared to preshift. In conclusion this study suggests that boilermakers exposed to occupational particulates are exposed to PAH. The urinary 1-OHP level may be a useful biomarker of PAH exposure in boilermakers exposed to ROFA, particularly in nonsmokers.

Adult↗

PubMed2002

Effects of air pollutants on acute stroke mortality.

The relationship between stroke and air pollution has not been adequately studied. We conducted a time-series study to examine the evidence of an association between air pollutants and stroke over 4 years (January 1995-December 1998) in Seoul, Korea. We used a generalized additive model to regress daily stroke death counts for each pollutant, controlling for seasonal and long-term trends and meteorologic influences, such as temperature, relative humidity, and barometric pressure. We observed an estimated increase of 1.5% [95% confidence interval (CI), 1.3-1.8%] and 2.9% (95% CI, 0.3-5.5%) in stroke mortality for each interquartile range increase in particulate matter < 10 microm aerodynamic diameter (PM(10)) and ozone concentrations in the same day. Stroke mortality also increased 3.1% (95% CI, 1.1-5.1%) for nitrogen dioxide, 2.9% (95% CI, 0.8-5.0%) for sulfur dioxide, and 4.1% (95% CI, 1.1-7.2%) for carbon monoxide in a 2-day lag for each interquartile range increase in single-pollutant models. When we examined the associations among PM(10) levels stratified by the level of gaseous pollutants and vice versa, we found that these pollutants are interactive with respect to their effects on the risk of stroke mortality. We also observed that the effects of PM(10) on stroke mortality differ significantly in subgroups by age and sex. We conclude that PM(10) and gaseous pollutants are significant risk factors for acute stroke death and that the elderly and women are more susceptible to the effect of particulate pollutants.

Adolescent↗

PubMed2002

Environmental organochlorines and semen quality: results of a pilot study.

There have been numerous studies that suggest that sperm concentrations (sperm counts) are declining in men. However, other studies suggest that sperm counts are not declining or may be increasing in some areas. Although there is disagreement on whether there is a downward temporal trend in sperm counts, the studies provide evidence that sperm counts vary by geographic location. It has been hypothesized that the geographic variation in sperm concentrations may be due to environmental exposures, lifestyle factors, or some unknown causes. To determine whether contemporary ambient levels of polychlorinated biphenyls (PCBs) and p,p-DDE are associated with altered semen quantity and quality, we selected a study population without specific exposure to PCBs or p,p-DDE. The present study presents the results from a pilot study on the relationship between serum PCBs and p,p-DDE and semen quality in 29 subjects recruited from the Massachusetts General Hospital Andrology Laboratory. Of the 29 subjects, 3 had sperm concentrations < 20 million/mL, 7 had < 50% motile sperm, 9 had < 4% normal morphology, and 6 were below normal in more than one semen parameter. The 18 subjects with normal spermatozoa concentration, motility, and morphology were used as comparison subjects. The mean (SE) concentration of the sum of PCBs and p,p-DDE was 242 ng/g lipids (34.0) and 354 ng/g lipids (120), respectively, for men with below normal motility as compared to 202 ng/g lipids (16.6) and 240 ng/g lipids (31.1), respectively, for the comparison subjects. The data showed general trends that were suggestive of an association between PCBs and p,p-DDE and abnormal motility, as well as with sperm concentration and morphology. A full-scale study is currently in progress.

Adult↗

PubMed2002

The association of particulate air metal concentrations with heart rate variability.

Numerous studies show an association between particulate air pollution and adverse health effects. Particulate matter is a complex mixture of elemental carbon, ammonium, sulfates, nitrates, organic components, and metals. The mechanisms of action of particulate matter less than or equal to 2.5 micro m in mean aerodynamic diameter (PM(2.5)), as well as the constituents responsible for the observed cardiopulmonary health effects, have not been identified. In this study we focused on the association between the metallic component of PM(2.5) and cardiac autonomic function based on standard heart rate variability (HRV) measures in an epidemiologic study of boilermakers. Thirty-nine male boilermakers were monitored throughout a work shift. Each subject wore an ambulatory electrocardiogram (Holter) monitor and a personal monitor to measure PM(2.5). We used mixed-effects models to regress heart rate and SDNN index (standard deviation of the normal-to-normal) on PM(2.5) and six metals (vanadium, nickel, chromium, lead, copper, and manganese). There were statistically significant mean increases in the SDNN index of 11.30 msec and 3.98 msec for every 1 micro g/m(3) increase in the lead and vanadium concentrations, respectively, after adjusting for mean heart rate, age, and smoking status. Small changes in mean heart rate were seen with all exposure metrics. The results of this study suggest an association between exposure to airborne metals and significant alterations in cardiac autonomic function. These results extend our understanding of the adverse health effects of the metals component of ambient PM(2.5).

Adult↗

PubMed2002

Spirometric abnormalities associated with chronic bronchitis, asthma, and airway hyperresponsiveness among boilermaker construction workers.

STUDY OBJECTIVES: In a 2-year longitudinal study of boilermaker construction workers, we found a significant association between working at oil-fired, coal-fired, and gas-fired industries during the past year and reduced lung function. In the present study, we investigated whether chronic bronchitis, asthma, or baseline methacholine airway responsiveness can explain the heterogeneity in lung function response to boilermaker work. DESIGN: This study is part of an ongoing prospective cohort study of boilermakers. Exposure was assessed with a work history questionnaire. Spirometry was performed annually to assess lung function. A generalized estimating equation approach was used to account for the repeated-measures design. SETTING: Boilermaker union members. PARTICIPANTS: One hundred eighteen boilermakers participated in the study. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Self-reported history of chronic bronchitis and asthma were associated with a larger FEV1 reduction in response to workplace exposure at coal-fired and gas-fired industries. Although we found a high prevalence (39%) of airway hyperresponsiveness (provocative concentration of methacholine causing a 20% fall in FEV1 of < 8 mg/mL) among boilermakers, we did not find a consistent pattern of effect modification by airway responsiveness. CONCLUSIONS: Although chronic bronchitis and asthma were associated with a greater loss in lung function in response to hours worked as a boilermaker, and therefore they acted as effect modifiers of the exposure-lung function relationship, airway hyperresponsiveness did not. However, the high prevalence of airway hyperresponsiveness found in the cohort may be a primary consequence of long-term workplace exposure among boilermakers.

Adult↗

PubMed2002

Prevention of work-related cancers.

Work-related cancers are highly preventable. The primary responsibility for prevention rests not with the workers who are affected by cancers, but with the manufacturers and distributors of carcinogenic substances and the companies who use them. U.S. public policies of strict product liability and the Occupational Safety and Health Act of 1970 address the issue of responsibility. Workers, health care providers, and others also have important roles that complement employers' preventive efforts. The range of prevention strategies available includes ones that should be applied to prevent potentially carcinogenic substances from being marketed and distributed; others that apply in the workplace where potential carcinogens are used; and public policy interventions aimed at ensuring universal implementation of pre-market and workplace prevention strategies. Work-related cancer remains a large problem, even though strategies exist to identify carcinogens and prevent and control on-the-job exposures. However, preventive efforts by government and the society have stalled and a continuing lack of toxicity information shows inadequate societal commitment. The principal barriers to prevention of work-related cancers are political and economic rather than scientific and medical.

Journal Article↗

PubMed2002

Genetic polymorphisms in N-acetyltransferase-2 and microsomal epoxide hydrolase, cumulative cigarette smoking, and lung cancer.

N-acetyltrasferase-2 (NAT2) and microsomal epoxide hydrolase (mEH) are polymorphic genes that metabolize different tobacco carcinogens. Smaller studies found inconsistent relationships between NAT2 or mEH polymorphisms and lung cancer risk. To determine whether there is gene-environment interaction between NAT2 polymorphisms, alone or in combination with mEH polymorphisms, and cumulative smoking exposure in the development of lung cancer, we conducted a case control study of 1115 Caucasian lung cancer patients and 1250 spouse and friend controls. The results were analyzed using generalized additive models and logistic regression, adjusting for relevant covariates. There was no overall relationship between NAT2 genotype and lung cancer risk; the adjusted odds ratio (OR) of the rapid versus slow acetylator genotypes was 0.96 [95% confidence interval (CI), 0.79-1.16]. However, gene-environment interaction analyses revealed that the adjusted ORs increased significantly as pack-years increased. For nonsmokers, the fitted OR was 0.66 (95% CI, 0.44-0.99), whereas for heavy smokers (80 pack-years), the OR increased to 1.22 (95% CI, 0.89-1.67). When comparing the extreme genotype combinations of the NAT2 rapid acetylator, higher mEH activity genotype to the NAT2 slow acetylator, and very low mEH activity genotype, the corresponding ORs at 0 and 80 pack-years were 0.30 (95% CI, 0.14-0.62) and 2.19 (95% CI, 1.26-3.81), respectively. Results were similar with ORs derived from stratified models. In conclusion, NAT2 rapid acetylator genotypes are protective against lung cancer in nonsmokers but are risk factors in heavy smokers. The joint effects of NAT2 and mEH polymorphisms are consistent with an independent, additive effect of these two genes, modified by smoking history.

Adult↗

PubMed2002

Relationship of exposure to coke-oven emissions and urinary metabolites of benzo(a)pyrene and pyrene in coke-oven workers.

Coke-oven workers are occupationally exposed to a high concentration of polycyclic aromatic hydrocarbons (PAH). r-7,t-8,9,c-10-Tetrahydroxy-7,8,9,10-tetrahydrobenzo(a)pyrene (trans-anti-BaP-tetraol) and 1-hydroxypyrene (1-OHP) are urinary metabolites of benzo(a)pyrene and pyrene, respectively. In this study, we investigated the relationship among individual air exposure to benzene soluble fraction (BSF) of total particulates, as a surrogate marker of ambient PAH exposures, and urinary trans-anti-BaP-tetraol and 1-OHP concentrations in coke-oven workers at a steel plant in Taiwan. Fifty-seven subjects, including 41 male workers who work in one coke-oven plant and 16 men (referents) from an administrative area, were studied. The mean trans-anti-BaP-tetraol and 1-OHP concentrations (mean +/- SD) were 0.4 +/- 0.3 nmol/mol creatinine and 9.7 +/- 21.6 micromol/mol creatinine, respectively, in coke-oven workers. These levels were significantly higher than those in referents (0.03 +/- 0.03 nmol/mole creatinine, P < 0.001 and 0.4 +/- 0.2 micromol/mol creatinine, P < 0.01, respectively). Urinary trans-anti-BaP-tetraol concentrations were significantly and positively correlated with individual average BSF and urinary 1-OHP concentrations. That is, the higher the urinary trans-anti-BaP-tetraol concentrations, the more ambient BSF exposure and urinary 1-OHP concentrations (Spearman correlation coefficients r = 0.68 and 0.70, respectively; P < 0.0001; n = 57). These findings suggest that urinary 1-OHP and trans-anti-BaP-tetraol might be considered as potential biomarkers for the assessment of uptake of known PAH carcinogens in the air.

Adult↗

PubMed2002

Stability of arsenic species and insoluble arsenic in human urine.

Urinary arsenic species are important short-term biomarkers that have been used in epidemiological studies. However, the stability of soluble arsenic species and the amount of arsenic lost during sample pretreatment remain unclear. The objective of this study is to evaluate the stability of soluble arsenic species in urine and aqueous standards, as well as to assess the amount of insoluble and soluble arsenic lost during pretreatment (centrifugation and filtration, respectively). High-performance liquid chromatogram inductively coupled plasma mass spectrometry was used to speciate arsenic species [Arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid [MMA(V)], monomethylarsonous acid [MMA(III)], dimethylarsinic acid [DMA(V)], and arsenobetaine [AsB]] in aqueous standards and in urine samples. The arsenic levels in both freshly collected urine samples (pH = 5.5-7.0) and National Institute of Standards and Technology Standard Reference Material 2670 toxic elements in frozen-dried urine (pH 4.4) remained constant up to 6 months when stored at -20 degrees C. In an aqueous solution mixed with 10 micro g/liter of As(III), As(V), MMA, and DMA standards, and stored at 4 degrees C, As(III) and As(V) were stable only up to 4 weeks, and MMA and DMA remained stable up to 4.5 months. The same phenomenon was observed for 100 micro g/liter mixed aqueous standards. There was no significant loss of arsenic species in urine (<5%) when passed through a 0.45- micro m filter. The amounts of insoluble arsenic in urine lost during centrifuge ranged from 1/2 to 1/17 of soluble arsenic. These findings indicated that the urinary matrix plays an important role in stabilizing arsenic species. Also, the loss of insoluble arsenic in urine during centrifuging results in underestimation of arsenic exposure, and may explain the lack of an association between arsenic exposure and the risk of health outcomes reported in some epidemiological studies.

Arsenates↗

PubMed2002

Counterpoint: the myeloperoxidase -463G-->a polymorphism does not decrease lung cancer susceptibility in Caucasians.

The myeloperoxidase (MPO) G-to-A substitution polymorphism in the promoter region of the MPO gene has been associated with a 40-70% reduction in lung cancer risk in several studies, although a recent nested case-control study disputes these findings. MPO is involved in the activation of a number of procarcinogens, including benzo(a)pyrene. The variant A allele has been shown to reduce MPO mRNA expression, thus potentially decreasing carcinogen activation. To confirm results from smaller studies, we evaluated this MPO polymorphism in 988 incident Caucasian lung cancer cases and 1128 controls. Logistic regression evaluated the association between MPO genotype and lung cancer risk, adjusting for age, gender, smoking status, time since quitting smoking, and pack-years of smoking. In the controls, the A allele frequency was 21%, and genotype distribution was in the Hardy-Weinberg equilibrium. Compared with the wild-type G/G genotype, the adjusted odds ratios for the A/A and A/G genotypes were 1.15 (95% confidence interval 0.7-1.9, P > 0.2) and 1.03 (95% confidence interval 0.8-1.3, P > 0.20), respectively. A similar lack of association was seen in analyses stratified by smoking status, median age, a number of smoking variables, disease stage, tumor grade, and histological subtype. These findings are in contrast with earlier studies suggesting a protective effect of carrying the variant A allele.

Adult↗

PubMedDate not supplied

Parental exposure to organic solvents and reduced birth weight.

The authors investigated the association of birth weight with maternal and paternal exposure to organic solvents in 1,222 couples employed in a large petrochemical corporation in Beijing, China, during the period between 1994 and 1998. A trained interviewer assessed parental exposures to organic solvents. The authors used generalized additive models to examine the association between birth weight and parental exposure to organic solvents. After the authors adjusted for potential confounders, maternal exposure to solvents was significantly associated with reduced birth weight (-81.7 gm, 95% confidence interval = -106.3, -3.1), and reduced birth weights of female babies and of younger mothers' babies were statistically significant. Maternal exposure to organic solvents was associated with reduced birth weight in this population, but paternal exposure to organic solvents was not similarly associated.

Adult↗

PubMedDate not supplied

Prospective surveillance of hypertension in firefighters.

The authors evaluated blood pressure and antihypertensive medication use in 334 firefighters in an occupational medical surveillance program. Firefighters received written summaries of their examination results, including blood pressures, and were encouraged to see their personal physicians for any abnormal results. The mean age of the participants was 39 years, and the vast majority were men (n=330). The prevalence of hypertension was 20% at baseline (1996), 23% in 1998, and 23% in 2000. Among firefighters with high blood pressure readings, only 17%, 25%, and 22% were taking antihypertensive medications at the baseline, 1998, and 2000 examinations, respectively. Medical surveillance was effective in detecting hypertension in firefighters; however, after 4 years of follow-up, only 42% of hypertensives were receiving treatment with medications, including only 22% of firefighters with hypertensive readings. Overall, 74% of hypertensives were not adequately controlled. Possible reasons for low treatment rates may be the inadequate recognition among primary care physicians that mild hypertension is a significant risk factor for cardiovascular disease.

Adult↗