Assessment of exposure to secondhand smoke at outdoor bars and family restaurants in Athens, Georgia, using salivary cotinine.

Exposure to secondhand smoke (SHS) in outdoor settings is a growing public health concern due to recent indoor smoking bans. The objective of this study was to measure salivary cotinine, a metabolite of nicotine, in subjects aged 21-30 exposed to SHS outside bars and restaurants in Athens, Georgia. Nonsmokers participated during 6-hr periods in outdoor standing or seating areas of bars and restaurants where indoor smoking was banned, as well as a control outdoor location with no smokers over six weekends during the summer and early fall of 2007. Pre- and post-exposure saliva samples (N = 25 person-days at the bar site, N = 28 person-days at the restaurant site, and N = 11 person-days at the control) were collected and analyzed for cotinine. The mean change in the response, (ln(post) - ln(pre)) salivary cotinine levels, was significantly impacted by the type of site (bar, restaurant, control) (F = 5.09; d.f. = 2, 6.7; p = 0.0455). The median percent increase in salivary cotinine from pre-test to post-test was estimated to be 162%, 102%, and 16% at the bar, restaurant, and control sites, respectively, values that were significant increases at bars (t = 4.63; d.f. = 9.24; p = 0.0011) and restaurants (t = 4.33; d.f. = 4.47; p = 0.0097) but not at the control sites. On average, these pre-test to post-test increases in salivary cotinine were significantly higher at bar sites than control sites (t = 3.05; d.f. = 9.85; p = 0.0176) and at restaurant sites compared with control sites (t = 2.35; d.f. = 5.09; p = 0.0461). Nonsmokers outside restaurants and bars in Athens, Georgia, have significantly elevated salivary cotinine levels indicative of secondhand smoke exposure.

A summary of recent findings on birth outcomes and developmental effects of prenatal ETS, PAH, and pesticide exposures.

Inner-city minority populations are high-risk groups for adverse birth outcomes and also more likely to be exposed to environmental contaminants, including environmental tobacco smoke (ETS), benzo[a]pyrene B[a]P, other ambient polycyclic aromatic hydrocarbons (global PAHs), and residential pesticides. The Columbia Center for Children's Environmental Health (CCCEH) is conducting a prospective cohort study of 700 northern Manhattan pregnant women and newborns to examine the effects of prenatal exposure to these common toxicants on fetal growth, early neurodevelopment, and respiratory health. This paper summarizes results of three published studies demonstrating the effects of prenatal ETS, PAH, and pesticides on birth outcomes and/or neurocognitive development [Perera FP, Rauh V, Whyatt RM, Tsai WY, Bernert JT, Tu YH, et al. Molecular evidence of an interaction between prenatal environment exposures on birth outcomes in a multiethnic population. Environ Health Perspect 2004;12:630-62; Rauh VA, Whyatt RM, Garfinkel R, Andrews H, Hoepner L, Reyes A, et al. Developmental effects of exposure to environmental tobacco smoke and material hardship among inner-city children. Neurotoxicol Teratol 2004;26:373-85; Whyatt RM, Rauh V, Barr DB, Camann DE, Andrews HF, Garfinkel R, et al. Prenatal insecticide exposures, birth weight and length among an urban minority cohort. Environ Health Perspect, in press]. To evaluate the effects of prenatal exposure to ETS, PAHs, and pesticides, researchers analyzed questionnaire data, cord blood plasma (including biomarkers of ETS and pesticide exposure), and B[a]P-DNA adducts (a molecular dosimeter of PAHs). Self-reported ETS was associated with decreased head circumference (P = 0.04), and there was a significant interaction between ETS and adducts such that combined exposure had a significant multiplicative effect on birth weight (P = 0.04) and head circumference (P = 0.01) after adjusting for confounders. A second analysis examined the neurotoxic effects of prenatal ETS exposure and postpartum material hardship (unmet basic needs in the areas of food, housing, and clothing) on 2-year cognitive development. Both exposures depressed cognitive development (P < 0.05), and there was a significant interaction such that children with exposure to both ETS and material hardship exhibited the greatest cognitive deficit (7.1 points). A third analysis found that cord chlorpyrifos, and a combined measure of cord chlorpyrifos, diazinon, and propoxur-metabolite, were inversely associated with birth weight and/or length (P < 0.05). These results underscore the importance of policies that reduce exposure to ETS, air pollution, and pesticides with potentially adverse effects on fetal growth and child neurodevelopment.

Households contaminated by environmental tobacco smoke: sources of infant exposures.

OBJECTIVES: To examine (1) whether dust and surfaces in households of smokers are contaminated with environmental tobacco smoke (ETS); (2) whether smoking parents can protect their infants by smoking outside and away from the infant; and (3) whether contaminated dust, surfaces, and air contribute to ETS exposure in infants. DESIGN: Quasi-experiment comparing three types of households with infants: (1) non-smokers who believe they have protected their children from ETS; (2) smokers who believe they have protected their children from ETS; (3) smokers who expose their children to ETS. SETTING: Homes of smokers and non-smokers. PARTICIPANTS: Smoking and non-smoking mothers and their infants < or = 1 year. MAIN OUTCOME MEASURES: ETS contamination as measured by nicotine in household dust, indoor air, and household surfaces. ETS exposure as measured by cotinine levels in infant urine. RESULTS: ETS contamination and ETS exposure were 5-7 times higher in households of smokers trying to protect their infants by smoking outdoors than in households of non-smokers. ETS contamination and exposure were 3-8 times higher in households of smokers who exposed their infants to ETS by smoking indoors than in households of smokers trying to protect their children by smoking outdoors. CONCLUSIONS: Dust and surfaces in homes of smokers are contaminated with ETS. Infants of smokers are at risk of ETS exposure in their homes through dust, surfaces, and air. Smoking outside the home and away from the infant reduces but does not completely protect a smoker's home from ETS contamination and a smoker's infant from ETS exposure.

Environmental and behavioral predictors of salivary cotinine in Latino tobacco workers.

We report the results of a cohort study of 182 seasonal and migrant farmworkers engaged in tobacco production in two North Carolina counties. Data were collected on tobacco work tasks and risk factors for exposure to nicotine, including smoking, every 2 weeks over a 10-week period during the summer of 1999. Saliva samples were collected for cotinine analysis at every contact. Salivary cotinine levels increased across the season, independent of smoking status. Multivariate analyses identified a model (R2 = 0.68) in which predictors of cotinine included greater age, later-season work, wet working conditions, smoking, and work task. Harvesting ("priming") tobacco was associated with higher cotinine levels than other tasks. This study demonstrates that tobacco workers experience substantial work-related exposure to nicotine. The long-term effects of such exposure should be investigated.

Comparison of serum and salivary cotinine measurements by a sensitive high-performance liquid chromatography-tandem mass spectrometry method as an indicator of exposure to tobacco smoke among smokers and nonsmokers.

Exposure to tobacco smoke, both from active smoking and from passive exposure to environmental tobacco smoke, can be monitored by measuring cotinine, a metabolite of nicotine, in a variety of biological sources including blood, urine, and saliva. Previously, a sensitive atmospheric-pressure ionization, tandem mass spectrometric (LC-API-MS-MS) method for cotinine measurements in serum was developed in support of a large, recurrent national epidemiologic investigation. The current study examined the application of this LC-API-MS-MS method to both serum and saliva cotinine measurements in a group of 200 healthy adults, including both smokers and nonsmokers. The primary objective of this study was to evaluate the relationship between serum and saliva cotinine concentrations to facilitate the linking of results from epidemiologic studies using salivary cotinine measurements to existing national data based on serum cotinine analyses. The results indicate that a simple, linear relationship can be developed to describe serum and saliva cotinine concentrations in an individual, and the expression describing this relationship can be used to estimate with reasonable accuracy (approximately +/- 10%) the serum cotinine concentration in an individual given his or her salivary cotinine result. It was further confirmed that saliva cotinine samples are generally quite stable during storage after collection, even at ambient temperatures, and this sample matrix appears to be well-suited to the requirements of many epidemiologic investigations.

Effect of counselling mothers on their children's exposure to environmental tobacco smoke: randomised controlled trial.

OBJECTIVE: To test the efficacy of behavioural counselling for smoking mothers in reducing young children's exposure to environmental tobacco smoke. DESIGN: Randomised double blind controlled trial. SETTING: Low income homes in San Diego county, California. PARTICIPANTS: 108 ethnically diverse mothers who exposed their children (aged <4 years) to tobacco smoke in the home. INTERVENTION: Mothers were given seven counselling sessions over three months. MAIN OUTCOME MEASURES: Children's reported exposure to environmental tobacco smoke from mothers in the home and from all sources; children's cotinine concentrations in urine. RESULTS: Mothers' reports of children's exposure to their smoke in the home declined in the counselled group from 27.30 cigarettes/week at baseline, to 4.47 at three months, to 3.66 at 12 months and in the controls from 24.56, to 12.08, to 8.38. The differences between the groups by time were significant (P=0.002). Reported exposure to smoke from all sources showed similar declines, with significant differences between groups by time (P=0.008). At 12 months, the reported exposure in the counselled group was 41.2% that of controls for mothers' smoke (95% confidence interval 34.2% to 48.3%) and was 45.7% (38.4% to 53.0%) that of controls for all sources of smoke. Children's mean urine cotinine concentrations decreased slightly in the counselled group from 10.93 ng/ml at baseline to 10.47 ng/ml at 12 months but increased in the controls from 9.43 ng/ml to 17.47 ng/ml (differences between groups by time P=0.008). At 12 months the cotinine concentration in the counselled group was 55.6% (48.2% to 63.0%) that of controls. CONCLUSIONS: Counselling was effective in reducing children's exposure to environmental tobacco smoke. Similar counselling in medical and social services might protect millions of children from environmental tobacco smoke in their homes.

Measuring secondhand smoke exposure in babies: the reliability and validity of mother reports in a sample of low-income families.

The reliability and validity of mother's reports of their infants' exposure to secondhand smoke (SHS) were examined in an ethnically diverse sample of low-income, low-education families (N = 141 mothers). At baseline and posttest, smoking mothers reported about their infants' SHS exposure at different locations and by different sources during the previous week. Findings show that mothers can give reliable accounts of the degree to which they contribute to their babies' SHS exposure. Mothers are able to differentiate between their own smoking behavior and the extent to which they expose their infants. Consistent with the overall exposure pattern, exposure caused by the mother and exposure occurring at home showed the strongest associations with biological and environmental measures. These findings suggest that smoking mothers can provide reliable and valid reports of the degree to which their infants are exposed to SHS.

Measuring environmental tobacco smoke exposure in infants and young children through urine cotinine and memory-based parental reports: empirical findings and discussion.

OBJECTIVE: This study examined the reliability and potential biases of two urine collection methods from which cotinine measures were obtained and the validity of memory-based parental reports of their children's exposure to environmental tobacco smoke (ETS). DESIGN: Structured interviews were conducted with mothers of infants and young children to obtain memory-based estimates of recent ETS exposure. Urine samples were collected through standard and cotton roll collection methods for cotinine analysis. SETTING: All interviews took place at an off-campus research facility. Urine samples were collected at the study office or the subjects' homes. PARTICIPANTS: Mothers were recruited from San Diego county sites of the Women, Infants, and Children (WIC) Supplemental Food and Nutrition Program. Sample 1 (infants) consisted of eight boys and eight girls aged 1-44 months (mean = 12.6 months). Sample 2 (children) included 10 boys and 10 girls aged 3-8 years (mean = 61.2 months). MAIN OUTCOME MEASURES: Urine cotinine and memory-based parent reports of ETS exposure from structured interviews. RESULTS: There was overall high reliability for urine cotinine measures and no effect of collection method on urine cotinine levels. Memory-based reports obtained from smoking mothers showed moderately strong and consistent linear relationships with urine cotinine measures of their infants and children (r = 0.50 to r = 0.63), but not for reports obtained from non-smoking mothers. CONCLUSIONS: Memory-based parental reports of short-term ETS exposure can play an important role in quantifying ETS exposure in infants and children.

Evaluation of four maternal smoking questions.

OBJECTIVE: The authors evaluated four questions about maternal smoking during pregnancy for use on birth certificates. METHODS: Question 1 (yes/no format) and Question 2 (trimester-specific design) were tested among 1171 women who delivered at two Kaiser Permanente medical centers in northern California. Responses to Questions 1 and 2 were compared with smoking information provided by participants in telephone interviews conducted during pregnancy. Question 3 (multiple choice format) and Question 4 (month- and grouped month-specific design) were tested among 900 women who enrolled in a statewide prenatal screening program and who delivered in 20 hospitals in four Central Valley counties. Responses to Questions 3 and 4 were compared with mid-pregnancy serum cotinine levels. The authors evaluated the four questions in terms of conciseness, response rate, data accuracy, and type of data requested. RESULTS: Questions 1 and 2 were the most concise. Response rates could not be calculated for Questions 1 and 2. Response rates were 86.0% for Question 3 and 74.2% for Question 4. Sensitivity was 47.3% for Question 1, 62.1% for Question 2, 83.8% for Question 3, and 86.7% for Question 4. The types of data requested by Questions 2 and 4 seem to best satisfy the needs of the broad audience of birth certificate users. CONCLUSIONS: No single question was clearly superior. The authors propose a combination of Questions 2 and 4, which asks about average number of cigarettes smoked per day in the three months before pregnancy and in each trimester of pregnancy.

Serum fatty acids and the risk of fatal cancer. MRFIT Research Group. Multiple Risk Factor Intervention Trial.

To examine the relation between serum fatty acids and cancer, the authors conducted a nested case-control study of 108 middle-aged men who died of cancer and 215 men without cancer, who were enrolled in the Multiple Risk Factor Intervention Trial (MRFIT) between 1973 and 1976. Control subjects were matched to case subjects on age, smoking status, treatment assignment, date of randomization, and clinical center. After confirming the stability of the stored serum samples, the authors measured serum fatty acid levels by gas-liquid chromatography and analyzed their association with cancer. In stepwise logistic regression analyses that controlled for the MRFIT selection criteria variables and for alcohol consumption, no fatty acid was significantly associated with overall risk of cancer death (all p > 0.05). Serum levels of phospholipid dihomogammalinolenic acid (20:3), an essential fatty acid, were inversely associated with the risk of dying from lung cancer; a standard deviation increase was associated with a 32% decrease in risk (p = 0.05). Dietary cholesterol intake was associated with the risk of nonlung, non-digestive tract cancers; a standard deviation increase (331 mg/day) was associated with a 75% increase in risk (p = 0.02). The authors found no evidence to suggest that increased dietary intake or serum levels of polyunsaturated fatty acids were associated with an increased risk of fatal cancer among middle-aged men at high risk for coronary heart disease. The clinical significance of the inverse association between dihomogammalinolenic acid and lung cancer death is uncertain and requires confirmation.

Exposure of casino employees to environmental tobacco smoke.

Environmental and medical evaluations were performed to evaluate occupational exposure to environmental tobacco smoke (ETS) among casino employees. Air concentrations of both nicotine and respirable dust were similar to those published in the literature for other non-industrial indoor environments. The geometric mean serum cotinine level of the 27 participants who provided serum samples was 1.34 nanograms per milliliter (ng/mL) (pre-shift) and 1.85 ng/mL (post-shift). Both measurements greatly exceeded the geometric mean value of 0.65 ng/mL for participants in the Third National Health and Nutrition Examination Survey (NHANES III) who reported exposure to ETS at work. This evaluation demonstrates that a sample of employees working in a casino gaming area were exposed to ETS at levels greater than those observed in a representative sample of the US population, and that the serum and urine cotinine of these employees increased during the workshift.

An evaluation of the use of dried blood spots from newborn screening for monitoring the prevalence of cocaine use among childbearing women.

A collaborative March of Dimes study was designed to examine the utility of dried blood spot (DBS) materials routinely collected from newborns as a source for monitoring cocaine exposure and to assess the prevalence of cocaine use among childbearing women in Georgia. We used a modified urinary radioimmunoassay (RIA) to anonymously detect the cocaine metabolite benzoylecgonine (BE) in DBSs. Extensive efforts were undertaken to assure absolute nonlinkage of BE data to any individual. The positive results found by RIA were confirmed by a mass spectrometry (MS) method specifically developed to detect BE in DBSs. BE was measured in 23,141 DBSs collected during 2 months of routine newborn screening in Georgia. A good correlation was observed for RIA results versus MS results (r2 = 0.97). The estimated minimal statewide BE prevalence was 4.8 per 1000 childbearing women. We demonstrated that immunoassay testing for cocaine without confirmatory testing can yield falsely elevated prevalence rates. When proper confirmatory testing is done, DBSs are a valuable source for population-based monitoring of substance abuse among childbearing women.

Development and validation of sensitive method for determination of serum cotinine in smokers and nonsmokers by liquid chromatography/atmospheric pressure ionization tandem mass spectrometry.

We describe a sensitive and specific method for measuring cotinine in serum by HPLC coupled to an atmospheric pressure chemical ionization tandem mass spectrometer. This method can analyze 100 samples/day on a routine basis, and its limit of detection of 50 ng/L makes it applicable to the analysis of samples from nonsmokers potentially exposed to environmental tobacco smoke. Analytical accuracy has been demonstrated from the analysis of NIST cotinine standards and from comparative analyses by both the current method and gas chromatography/high-resolution mass spectrometry. Precision has been examined through the repetitive analysis of a series of bench and blind QC materials. This method has been applied to the analysis of cotinine in serum samples collected as part of the Third National Health and Nutrition Examination Survey (NHANES III).

Relation of smoking and alcohol consumption to serum fatty acids.

To examine the relation of cigarette smoking and alcohol consumption to serum fatty acid levels, the authors conducted a cross-sectional study of 190 men who were enrolled in the Multiple Risk Factor Intervention Trial between 1973 and 1976. After controlling for dietary fat, cholesterol, energy intake, and other potential confounders, the authors found that smoking and alcohol intake were associated with the serum cholesterol ester and phospholipid levels of several fatty acids. As the number of cigarettes smoked per day increased, the levels of cholesterol ester and phospholipid palmitoleic acid (16:1) and oleic acid (18:1) and the levels of phospholipid dihomogammalinolenic acid (20:3) and omega-9 eicosatrienoic acid (20:3) increased (all p's < or = 0.01). Serum levels of phospholipid omega-3 docosahexaenoic acid (22:6) and cholesterol ester and phospholipid arachidonic acid (20:4) were inversely associated with smoking (all p's < or = 0.01). As the number of alcoholic drinks per week increased, levels of cholesterol ester and phospholipid palmitic acid (16:0) and oleic acid (18:1), cholesterol ester myristic acid (14:0), and phospholipid palmitoleic acid (16:1), adrenic acid (22:4), and omega-9 eicosatrienoic acid (20:3) increased (all p's < 0.05), whereas levels of cholesterol ester and phospholipid linoleic acid (18:2) and phospholipid stearic acid (18:0) and the serum polyunsaturated fat: saturated fat ratio decreased (all p's < or = 0.01). These results suggest that smoking and alcohol consumption may influence the absorption, synthesis, or metabolism of serum fatty acids. Studies that use serum fatty acid levels as indicators of dietary fat intake should control for the effects of cigarette smoking and alcohol consumption.

Analysis of benzoylecgonine in dried blood spots by liquid chromatography--atmospheric pressure chemical ionization tandem mass spectrometry.

Residual samples from blood spots (i.e., whole blood spotted onto filter paper) are a useful source for epidemiological screening studies involving newborns. However, the small volume of blood available from residual blood spots complicates the assay. A method for analyzing benzoylecgonine (BZE; the primary metabolite of cocaine) in blood spots, in which the blood spot is eluted with aqueous ammonium acetate-methanol containing N-methyl trideuterated-BZE as an internal standard, followed by high-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry using multiple reaction monitoring, has been developed. This approach provides a rapid, direct, sensitive (limit of detection, approximately 2 ng/mL, based on a 12-microL sample size), and highly specific means of determining BZE concentrations in blood spots. We have applied this method for confirmatory analyses in a large epidemiological study of the prevalence of cocaine use during late pregnancy.

Exposure of the US population to environmental tobacco smoke: the Third National Health and Nutrition Examination Survey, 1988 to 1991.

OBJECTIVE: To estimate the extent of exposure of the US population to environmental tobacco smoke and the contribution of the home and workplace environment to environmental tobacco smoke exposure. DESIGN: Nationally representative cross-sectional survey including questionnaire information from persons aged 2 months and older (n=16818) and measurements of serum cotinine (a metabolite of nicotine) from persons aged 4 years and older (n=10642). SETTING/PARTICIPANTS: Participants in the Third National Health and Nutrition Examination Survey, October 25, 1988, to October 21, 1991. RESULTS: Of US children aged 2 months to 11 years, 43% lived in a home with at least 1 smoker, and 37% of adult non-tobacco users lived in a home with at least 1 smoker or reported environmental tobacco smoke exposure at work. Serum cotinine levels indicated more widespread exposure to nictoine. Of non-tobacco users, 87.9% had detectable levels of serum cotinine. Both the number of smokers in the household and the hours exposed at work were significantly and independently associated (P<.001, multiple regression t test) with increased serum cotinine levels. Serum cotinine levels of children, non-Hispanic blacks, and males indicated that these groups had higher exposure to environmental tobacco smoke. Dietary variables showed no consistent association with serum cotinine levels, and dietary contribution to serum cotinine level, if any, appeared to be extremely small. CONCLUSIONS: The high proportion of the population with detectable serum cotinine levels indicates widespread exposure to environmental tobacco smoke in the US population. Both the home and workplace environments significantly contribute to environmental tobacco smoke exposure in the United States.

Serum fatty acids and blood pressure.

To examine the relation between serum fatty acids and blood pressure, we conducted a cross-sectional study of 156 men who were enrolled in the Multiple Risk Factor Intervention Trial. After confirming the stability of the stored serum samples, we measured serum fatty acid levels by gas-liquid chromatography and examined their association with blood pressure. Using stepwise linear regression, we determined that each SD increase (1.9%) in the serum level of cholesterol ester palmitoleic acid (16:1) was associated with a systolic pressure increase of 3.3 mm Hg (95% confidence interval, 0.9 to 5.6 mm Hg) and each SD increase (0.1%) in phospholipid omega 9 eicosatrienoic acid (20:3) was associated with a diastolic pressure increase of 1.7 mm Hg (95% confidence interval, 0.5 to 2.9 mm Hg). Serum level of cholesterol ester steric acid (18:0) was inversely associated with diastolic pressure: each SD increase (0.2%) was associated with a decrease of 1.4 mm Hg (95% confidence interval, -2.5 to -0.2 mm Hg). In multivariate models that included dietary fat intake, cholesterol ester dihomogammalinolenic acid (20:3) was also associated with diastolic pressure: each SD increase (0.16%) was associated with an increase of 1.2 mm Hg (95% confidence interval, 0.1 to 2.4 mm Hg). Our results indicate that three nonessential fatty acids--stearic acid, palmitoleic acid, and omega 9 eicosatrienoic acid, and one essential fatty acid--dihomogammalinolenic acid, are independent correlates of blood pressure among middle-aged American men at high risk of coronary heart disease.

Serum fatty acids and the risk of coronary heart disease.

To examine the relation between serum fatty acids and coronary heart disease (CHD), the authors conducted a nested case-control study of 94 men with incident CHD and 94 men without incident CHD who were enrolled in the Usual Care group of the Multiple Risk Factor Intervention Trial between December 1973 and February 1976. After confirming the stability of the stored serum samples, the authors measured serum fatty acid levels by gas-liquid chromatography and examined their association with CHD. In all multivariate models, levels of the cholesterol ester saturated fatty acid palmitic acid (16:0) were directly associated with CHD risk (standardized odds ratio = 1.68; 95% confidence interval 1.10-2.55 in the model that adjusted for total plasma cholesterol level). Levels of the phospholipid omega-3 fatty acid docosapentaenoic acid (22:5) were inversely associated with CHD risk in the two multivariate models that controlled for the effects of total plasma cholesterol level or high density lipoprotein cholesterol to total plasma cholesterol ratio (standardized odds ratio = 0.58; 95% confidence interval 0.38-0.89 in the first model that controlled for total plasma cholesterol level). In contrast to the first two multivariate models, levels of the docosahexaenoic acid (22:6) were inversely associated with CHD risk in a third multivariate model that controlled for the effects of high density lipoprotein cholesterol to low density lipoprotein cholesterol ratio (standardized odds ratio = 0.57; 95% confidence interval 0.36-0.90). These findings are consistent with other evidence indicating that saturated fatty acids are directly correlated with CHD and that omega-3 polyunsaturated fatty acids are inversely correlated with CHD. Because these associations were present after adjustment for blood lipid levels, other mechanisms, such as a direct effect on blood clotting, may be involved.

Serum fatty acids and the risk of stroke.

BACKGROUND AND PURPOSE: To examine the relationship between serum fatty acids, which reflect dietary intake, and stroke, we conducted a nested case-control study of 96 men with incident stroke and 96 control subjects matched by age, clinical center, treatment group, and date of randomization who were enrolled in the Multiple Risk Factor Intervention Trial. METHODS: After confirming the stability of the stored serum samples, we measured serum cholesterol ester and phospholipid fatty acid levels as the percentage of total fatty acids by gas-liquid chromatography and examined their association with incident stroke. Using stepwise conditional logistic regression that controlled for risk factors for stroke, we determined which fatty acids were independent correlates of stroke. RESULTS: In univariate models, a standard deviation (SD) increase (1.37%) in phospholipid stearic acid (18:0) was associated with a 37% increase in the risk of stroke, whereas an SD increase (0.06%) in phospholipid omega-3 alpha-linolenic acid (18:3) was associated with a 28% decrease in the risk of stroke (all P < .05). Only alpha-linolenic acid in the cholesterol ester fraction was associated with the risk of stroke in multivariate models: an SD increase (0.13%) in the serum level of alpha-linolenic acid was associated with a 37% decrease in the risk of stroke (P < .05). Systolic blood pressure and cigarette smoking were also independently associated with stroke risk. CONCLUSIONS: Our findings suggest that higher serum levels of the essential fatty acid alpha-linolenic acid are independently associated with a lower risk of stroke in middle-aged men at high risk for cardiovascular disease.