Chronic bronchitis and urban air pollution in an international study

Objectives

The chronic effects of urban air pollution are not well known. The authors'' aim was to investigate the association between the prevalence and new onset of chronic bronchitis and urban air pollution.

Methods

Subjects from the general population randomly selected for the European Community Respiratory Health Survey (ECRHS I) during 1991–93 in 21 centres in 10 countries were followed up from the years 2000 to 2002 (n = 3232 males and 3592 females; average response rate = 65.3%). PM_2.5 and elements, with the same equipment at centre level, and home outdoor NO₂ in 1634 individuals were measured. Hierarchical models were used.

Results

The prevalence and new onset of chronic phlegm during follow up were 6.9% and 4.5%, respectively, 5.3% in males and 3.5% in females. Smoking, rhinitis, poor education, and low social class were associated with (prevalence and new onset of) chronic phlegm in both genders, and occupational exposures in males and traffic intensity (adjusted odds ratio for constant traffic, OR = 1.86; 95% CI 1.24 to 2.77) as well as home outdoor NO₂ (OR > 50 μg/m³v < 20μg³  =  2.71; 95% CI 1.03 to 7.16) among females. PM_2.5 and S content at centre level did not show any association with prevalence or new onset of chronic phlegm. Similar results were obtained with chronic productive cough.

Conclusion

Individual markers of traffic at household level such as reported intensity and outdoor NO₂ were risk factors for chronic bronchitis among females.     

Occupational risk factors for nasopharyngeal cancer among female textile workers in Shanghai, China

Aims

To investigate whether occupational exposure to dusts and chemicals in the Chinese textile industry are associated with risk of nasopharyngeal cancer.

Methods

Sixty seven nasopharyngeal carcinoma (NPC) cases identified during 1989–98 and a random sample (n = 3188) of women were included in a case cohort study nested in a cohort of 267 400 women textile workers in Shanghai, China. A complete occupational history of work in the textile industry was obtained for each woman. A job exposure matrix developed by experienced industrial hygienists was used to assess exposures to specific dusts and chemicals.

Results

Risk of NPC is associated with cumulative exposure to cotton dust. The hazard ratio for women cumulatively exposed to >143.4 mg/m³ × years of cotton dust was 3.6 (95% CI 1.8 to 7.2) compared with unexposed women. Trends of increasing risk were also found with increasing duration of exposure to acids and caustics (p = 0.05), and with years worked in dyeing processes (p = 0.06). Women who worked at least 10 years in dyeing processes had a 3.6‐fold excess risk of NPC (95% CI 1.0 to 12.1).

Conclusions

Occupational exposure to cotton dust, acids, and caustics, and work in dyeing and printing jobs in the textile industry may have increased risk of NPC in this cohort.     

Noise exposure and hearing loss prevention programmes after 20 years of regulations in the United States

Objectives

To evaluate noise exposures and hearing loss prevention efforts in industries with relatively high rates of workers'' compensation claims for hearing loss.

Methods

Washington State workers'' compensation records were used to identify up to 10 companies in each of eight industries. Each company (n = 76) was evaluated by a management interview, employee personal noise dosimetry (n = 983), and employee interviews (n = 1557).

Results

Full‐shift average exposures were ⩾85 dBA for 50% of monitored employees, using Occupational Safety and Health Administration (OSHA) parameters with a 5 dB exchange rate (L_ave), but 74% were ⩾85 dBA using a 3 dB exchange rate (L_eq). Only 14% had L_ave ⩾90 dBA, but 42% had L_eq ⩾90 dBA. Most companies conducted noise measurements, but most kept no records, and consideration of noise controls was low in all industries. Hearing loss prevention programmes were commonly incomplete. Management interview scores (higher score = more complete programme) showed significant associations with percentage of employees having L_ave ⩾85 dBA and presence of a union (multiple linear regression; R² = 0.24). Overall, 62% of interviewed employees reported always using hearing protection when exposed. Protector use showed significant associations with percentage of employees specifically required to use protection, management score, and average employee time spent ⩾95 dBA (R² = 0.65).

Conclusions

The findings raise serious concerns about the adequacy of prevention, regulation, and enforcement strategies in the United States. The percentage of workers with excessive exposure was 1.5–3 times higher using a 3 dB exchange rate instead of the OSHA specified 5 dB exchange rate. Most companies gave limited or no attention to noise controls and relied primarily on hearing protection to prevent hearing loss; yet 38% of employees did not use protectors routinely. Protector use was highest when hearing loss prevention programmes were most complete, indicating that under‐use of protection was, in some substantial part, attributable to incomplete or inadequate company efforts.     

The risk of lung cancer with increasing time since ceasing exposure to asbestos and quitting smoking

Objectives

To examine if the risk of lung cancer declines with increasing time since ceasing exposure to asbestos and quitting smoking, and to determine the relative asbestos effect between non‐smokers and current smokers.

Methods

A cohort study of 2935 former workers of the crocidolite mine and mill at Wittenoom, who responded to a questionnaire on smoking first issued in 1979 and on whom quantitative estimates of asbestos exposure are known. Conditional logistic regression was used to relate asbestos exposure, smoking category, and risk of lung cancer.

Results

Eighteen per cent of the cohort reported never smoking; 66% of cases and 50% of non‐cases were current smokers. Past smokers who ceased smoking within six years of the survey (OR = 22.1, 95% CI 5.6 to 87.0), those who ceased smoking 20 or more years before the survey (OR = 1.9, 95% CI 0.50 to 7.2), and current smokers (<20 cigarettes per day (OR = 6.8, 95% CI 2.0 to 22.7) or >20 cigarettes per day (OR = 13.2, 95% CI 4.1 to 42.5)) had higher risks of lung cancer compared to never smokers after adjusting for asbestos exposure and age. The asbestos effect between non‐smokers and current smokers was 1.23 (95% CI 0.35 to 4.32).

Conclusion

Persons exposed to asbestos and tobacco but who subsequently quit, remain at an increased risk for lung cancer up to 20 years after smoking cessation, compared to never smokers. Although the relative risk of lung cancer appears higher in never and ex‐smokers than in current smokers, those who both smoke and have been exposed to asbestos have the highest risk; this study emphasises the importance of smoking prevention and smoking cessation programmes within this high risk cohort.     

The effectiveness of graded activity for low back pain in occupational healthcare

Background

Low back pain is a common medical and social problem associated with disability and absence from work. Knowledge on effective return to work (RTW) interventions is scarce.

Objective

To determine the effectiveness of graded activity as part of a multistage RTW programme.

Design

Randomised controlled trial.

Setting

Occupational healthcare.

Subjects

112 workers absent from work for more than eight weeks due to low back pain were randomised to either graded activity (n = 55) or usual care (n = 57).

Intervention

Graded activity, a physical exercise programme aimed at RTW based on operant‐conditioning behavioural principles.

Main outcome measures

The number of days off work until first RTW for more then 28 days, total number of days on sick leave during follow up, functional status, and severity of pain. Follow up was 26 weeks.

Results

Graded activity prolonged RTW. Median time until RTW was equal to the total number of days on sick leave and was 139 (IQR = 69) days in the graded activity group and 111 (IQR = 76) days in the usual care group (hazard ratio = 0.52, 95% CI 0.32 to 0.86). An interaction between a prior workplace intervention and graded activity, together with a delay in the start of the graded activity intervention, explained most of the delay in RTW (hazard ratio = 0.86, 95% CI 0.40 to 1.84 without prior intervention and 0.39, 95% CI 0.19 to 0.81 with prior intervention). Graded activity did not improve pain or functional status clinically significantly.

Conclusions

Graded activity was not effective for any of the outcome measures. Different interventions combined can lead to a delay in RTW. Delay in referral to graded activity delays RTW. In implementing graded activity special attention should be paid to the structure and process of care.     

Cross shift changes in lung function among bar and restaurant workers before and after implementation of a smoking ban

Objective

To study possible cross shift effects of environmental tobacco smoke (ETS) on pulmonary function among bar and restaurant employees before and after the implementation of a smoking ban in Norway.

Methods

The study included 93 subjects employed in 13 different establishments in Oslo. They were examined at the beginning and end of a workshift both while ETS exposure was present and when smoking was banned. The mean exposure level of nicotine and total dust before the ban was 28 μg/m³ (range 3–65) and 275 μg/m³ (range 81–506), respectively. Following the smoking ban, the mean level of nicotine and total dust was 0.6 μg/m³ and 77 μg/m³, respectively. Assessment of lung function included dynamic lung volumes and flows.

Results

The cross shift reduction in forced vital capacity (FVC) among 69 subjects participating in both examinations changed from 81 ml (SD 136) during exposure to ETS to 52 ml (SD 156) (p = 0.24) following the smoking ban. The reduction in forced expired volume in one second (FEV1) during a workshift, was borderline significantly reduced when comparing the situation before and after the intervention, by 89 ml (SD = 132) compared to 46 ml (SD = 152) (p = 0.09), respectively. The reduction in forced mid‐expiratory flow rate (FEF_25–75%) changed significantly from 199 ml/s (SD = 372) to 64 ml/s (SD = 307) (p = 0.01). Among 26 non‐smokers and 11 asthmatics, the reduction in FEV1 and FEF_25–75% was significantly larger during ETS exposure compared to after the smoking ban. There was an association between the dust concentration and decrease in FEF_25–75% before the ban among non‐smokers (p = 0.048).

Conclusions

This first study of cross shift changes before and after the implementation of a smoking ban in restaurants and bars shows a larger cross shift decrease in lung function before compared with after the implementation of the ban.     

Physical capacity in relation to low back, neck, or shoulder pain in a working population

Aims

To investigate the longitudinal relation between physical capacity (isokinetic lifting strength, static endurance of the back, neck, and shoulder muscles, and mobility of the spine) and low back, neck, and shoulder pain.

Methods

In this prospective cohort study, 1789 Dutch workers participated. At baseline, isokinetic lifting strength, static endurance of the back, neck, and shoulder muscles, and mobility of the spine were measured in the pain free workers, as well as potential confounders, including physical workload. Low back, neck, and shoulder pain were self‐reported annually at baseline and three times during follow up.

Results

After adjustment for confounders, Poisson generalised estimation equations showed an increased risk of low back pain among workers in the lowest sex specific tertile of performance in the static back endurance tests compared to workers in the reference category (RR = 1.42; 95% CI 1.19 to 1.71), but this was not found for isokinetic trunk lifting strength or mobility of the spine. An increased risk of neck pain was shown for workers with low performance in tests of isokinetic neck/shoulder lifting strength (RR = 1.31; 95% CI 1.03 to 1.67) and static neck endurance (RR = 1.22; 95% CI 1.00 to 1.49). Among workers in the lowest tertiles of isokinetic neck/shoulder lifting strength or endurance of the shoulder muscles, no increased risk of shoulder pain was found.

Conclusions

The findings of this study suggest that low back or neck endurance were independent predictors of low back or neck pain, respectively, and that low lifting neck/shoulder strength was an independent predictor of neck pain. No association was found between lifting trunk strength, or mobility of the spine and the risk of low back pain, nor between lifting neck/shoulder strength or endurance of the shoulder muscles and the risk of shoulder pain.     

Association of ventricular arrhythmias detected by implantable cardioverter defibrillator and ambient air pollutants in the St Louis, Missouri metropolitan area

Background

It has previously been reported that the risk of ventricular arrhythmias is positively associated with ambient air pollution among patients with implantable cardioverter defibrillators (ICD) in Boston.

Aims

To assess the association of community exposures to air pollution with ventricular arrhythmias in a cohort of ICD patients in metropolitan St Louis, Missouri.

Methods

ICD detected episodes reported during clinical follow up were abstracted and reviewed by an electrophysiologist to identify ventricular arrhythmias. A total of 139 ventricular arrhythmias were identified among 56 patients. A case‐crossover design was used with control periods matched on weekday and hour of the day within the same calendar month. Conditional logistic regression models were adjusted for temperature, barometric pressure, and relative humidity in the 24 hours preceding the event.

Results

There was a significant (24%, 95% CI 7% to 44%) increase in risk of ventricular arrhythmias associated with each 5 ppb increase in mean sulphur dioxide and non‐significantly increased risk (22%, 95% CI −6% to 60%; and 18%, 95% CI −7% to 50%) associated with increases in nitrogen dioxide (6 ppb) and elemental carbon (0.5 μg/m³), respectively in the 24 hours before the arrhythmia.

Conclusions

These results provide evidence of an association between ventricular arrhythmias and ambient air pollutants in St Louis. This is consistent with previous results from Boston, although the pollutants responsible for the increased risk are different.     

Cancer mortality in a synthetic spinning plant in Besançon, France

Objectives

To assess the mortality of a cohort of workers in a synthetic textile spinning plant and to evaluate the relationship between mortality from lung, liver and bladder cancer and the processes or the products used.

Methods

The study population consisted of male workers present for at least 6 months in the plant from 1968 to 1984. The cohort was followed until 1999. Vital status and the causes of death were determined by consulting national registries. The population of the Franche‐Comté region was used for comparison. In total, 17 groups of exposure were assessed by the industrial hygienist, based on the consensus of an expert group that determined the exposure levels of each job to selected occupational hazards. Each worker was assigned to one or several groups, according to his occupational history. Confounding factors could not be assessed. Standardised mortality ratios (SMR) and 95% bilateral confidence intervals were calculated based on an assumed Poisson distribution of the number of cases to compare the plant mortality and the population mortality. Internal analyses were performed with Cox models in order to assess the risks of death related to the various exposures.

Results

In the whole cohort, mortality from all malignant neoplasms was lower than expected, but this was not significant. All the estimated SMRs were lower than or close to 1. The “hot ‐line fitters” (RR = 2.13; n = 9; 1.06 to 4.29) and the “fibre‐drawing workers” (RR = 1.83; n = 20;1.09 to 3.07) experienced a statistically significant excess in mortality from lung cancer. A slightly elevated but not significant risk of death related to lung cancer (RR = 1.5; n = 41; 0.8 to 2.7) was observed in the groups with the highest exposure to mineral fibres. A statistically significant increase in cancer deaths was observed for workers with high exposure to dust (higher intensity: RR = 1.42; n = 79; 1.06 to 1.89).

Conclusion

Some findings, mainly of lung cancer, justify further exploration in other plants in this industry,     

Fertility and exposure to solvents among families in the Agricultural Health Study

Background

Several studies have reported associations between solvent exposure and reduced female fertility, but the evidence is inconclusive for male fertility.

Objectives

To investigate the impact of solvent exposure on subfertility among families of male licensed pesticide applicators in the Agricultural Health Study cohort.

Methods

The couples enrolled between 1993 and 1997. Cross‐sectional questionnaire information on work tasks was used to assess exposure to solvents. The data were limited to couples (wife aged less than 40 years) with an attempt at pregnancy in the last four years (n = 2112).

Results

Twenty eight per cent of the couples were defined as subfertile (not conceiving a pregnancy after at least 12 months of unprotected intercourse, regardless of whether or not a pregnancy ultimately occurred). Adjusted subfertility odds ratios (OR) for exposure to solvents were calculated with logistic regression. Female (OR 1.42, 95% CI 1.15 to 1.75) and male exposure to solvents (OR 1.21 (95% CI 0.93 to 1.57) for monthly exposure and 1.40 (95% CI 0.97 to 2.03) for daily or weekly exposure) were associated with subfertility. In farming, spouses may share or exchange jobs. To account for potential dual exposure, variables for parental exposure (either parent exposed or both parents exposed) were also defined. Both were strongly associated with subfertility (OR 1.62 (95% CI 1.20 to 2.17) and OR 2.10 (95% CI 1.22 to 3.60), respectively).

Conclusions

Solvents may impair fertility of either gender, though the evidence for female effects is stronger than for male effects.     

Household exposure to pesticides and risk of childhood acute leukaemia

Objectives

To investigate the relation between childhood acute leukaemia and household exposure to pesticides.

Methods

The study included 280 incident cases of acute leukaemia and 288 controls frequency matched on gender, age, hospital, and ethnic origin. The data were obtained from standardised face to face interviews of the mothers with detailed questions on parental occupational history, home and garden insecticide use, and insecticidal treatment of pediculosis. Odds ratios were estimated using unconditional regression models including the stratification variables parental socioeconomic status and housing characteristics.

Results

Acute leukaemia was observed to be significantly associated with maternal home insecticide use during pregnancy (OR = 1.8, 95% CI 1.2 to 2.8) and during childhood (OR = 1.7, 95% CI 1.1 to 2.4), with garden insecticide use (OR = 2.4, 95% CI 1.3 to 4.3), and fungicide use (OR = 2.5, 95% CI 1.0 to 6.2) during childhood. Insecticidal shampoo treatment of pediculosis was also associated with childhood acute leukaemia (OR = 1.9, 95% CI 1.2 to 3.3).

Conclusion

The results reported herein support the hypothesis that various types of insecticide exposure may be a risk factor for childhood acute leukaemia. The observed association with insecticidal shampoo treatment of pediculosis, which has never been investigated before, requires further study.     

Laboratory work and pregnancy outcomes: a study within the National Birth Cohort in Denmark

Aims

To examine pregnancy outcomes in women doing laboratory work.

Methods

Using data from the Danish National Birth Cohort (1997–2003), the authors conducted a prospective cohort study of 1025 female laboratory technicians and 8037 female teachers (as reference). The laboratory technicians were asked about laboratory work tasks during pregnancy in an interview (at around 16 weeks of gestation). Pregnancy outcomes were obtained by linking the cohort to the national registers. Hazard ratios (HRs) of late fetal loss and diagnosing of congenital malformations were calculated by using Cox regression, and odds ratios (ORs) of preterm birth and small for gestational age were calculated by using logistic regression.

Results

Overall, there were no significant differences in pregnancy outcomes between laboratory technicians and teachers. However, we found that laboratory technicians working with radioimmunoassay or radiolabelling had an increased risk of preterm birth (OR = 2.2, 95% CI 0.8 to 6.2 for radioimmunoassay, and OR = 1.9, 95% CI 0.8 to 4.6 for radiolabelling) and “major” malformations (HR = 2.1, 95% CI 1.0 to 4.7 for radioimmunoassay, and HR = 1.8, 95% CI 0.9 to 3.7 for radiolabelling). The ORs of preterm birth doubled for women working with these tasks every day or several times a week. When an exposure matrix was applied, an increased risk of “major” malformations for exposure to organic solvents was seen.

Conclusions

The results did not indicate any high risk of reproductive failures in laboratory technicians in general. Exposure to radioisotopes may carry a high risk of preterm birth and congenital malformations. This finding deserves further investigation.     

Brain tumours and exposure to pesticides: a case-control study in southwestern France

Background

Brain tumours are often disabling and rapidly lethal; their aetiology is largely unknown. Among potential risk factors, pesticides are suspected.

Objective

To examine the relationship between exposure to pesticides and brain tumours in adults in a population‐based case–control study in southwestern France.

Methods

Between May 1999 and April 2001, 221 incident cases of brain tumours and 442 individually matched controls selected from the general population were enrolled. Histories of occupational and environmental exposures, medical and lifestyle information were collected. A cumulative index of occupational exposure to pesticides was created, based on expert review of lifelong jobs and tasks. Separate analyses were performed for gliomas and meningiomas.

Results

A non‐statistically significant increase in risk was found for brain tumours when all types of occupational exposure to pesticides were considered (OR = 1.29, 95% CI 0.87 to 1.91) and slightly higher but still non‐statistically significant when gliomas were considered separately (OR = 1.47, 95% CI 0.81 to 2.66). In the highest quartile of the cumulative index, a significant association was found for brain tumours (OR = 2.16, 95% CI 1.10 to 4.23) and for gliomas (OR = 3.21, 95% CI 1.13 to 9.11), but not for meningiomas. A significant increase in risk was also seen for the treatment of home plants (OR = 2.24, 95% CI 1.16 to 4.30) owing to environmental exposure to pesticides.

Conclusions

These data suggest that a high level of occupational exposure to pesticides might be associated with an excess risk of brain tumours, and especially of gliomas.     

Ambient particulate air pollution and cardiac arrhythmia in a panel of older adults in Steubenville, Ohio

Objectives

Ambient particulate air pollution has been associated with increased risk of cardiovascular morbidity and mortality. Pathways by which particles may act involve autonomic nervous system dysfunction or inflammation, which can affect cardiac rate and rhythm. The importance of these pathways may vary by particle component or source. In an eastern US location with significant regional pollution, the authors examined the association of air pollution and odds of cardiac arrhythmia in older adults.

Methods

Thirty two non‐smoking older adults were evaluated on a weekly basis for 24 weeks during the summer and autumn of 2000 with a standardised 30 minute protocol that included continuous electrocardiogram measurements. A central ambient monitoring station provided daily concentrations of fine particles (PM_2.5, sulfate, elemental carbon) and gases. Sulfate was used as a marker of regional pollution. The authors used logistic mixed effects regression to examine the odds of having any supraventricular ectopy (SVE) or ventricular ectopy (VE) in association with increases in air pollution for moving average pollutant concentrations up to 10 days before the health assessment.

Results

Participant specific mean counts of arrhythmia over the protocol varied between 0.1–363 for SVE and 0–350 for VE. The authors observed odds ratios for having SVE over the length of the protocol of 1.42 (95% CI 0.99 to 2.04), 1.70 (95% CI 1.12 to 2.57), and 1.78 (95% CI 0.95 to 3.35) for 10.0 μg/m³, 4.2 μg/m³, and 14.9 ppb increases in five day moving average PM_2.5, sulfate, and ozone concentrations respectively. The other pollutants, including elemental carbon, showed no effect on arrhythmia. Participants reporting cardiovascular conditions (for example, previous myocardial infarction or hypertension) were the most susceptible to pollution induced SVE. The authors found no association of pollution with VE.

Conclusion

Increased levels of ambient sulfate and ozone may increase the risk of supraventricular arrhythmia in the elderly.     

Effort/reward imbalance and sedentary lifestyle: an observational study in a large occupational cohort

Objectives

To investigate the association between effort/reward imbalance (ERI) at work and sedentary lifestyle.

Methods

Cross sectional data from the ongoing Finnish Public Sector Study related to 30 433 women and 7718 men aged 17–64 were used (n = 35 918 after exclusion of participants with missing values in covariates). From the responses to a questionnaire, an aggregated mean score for ERI in a work unit was assigned to each participant. The outcome was sedentary lifestyle defined as <2.00 metabolic equivalent task (MET) hours/day. Logistic regression with generalised estimating equations was used as an analysis method to include both individual and work unit level predictors in the models. Adjustments were made for age, marital status, occupational status, job contract, smoking, and heavy drinking.

Results

Twenty five per cent of women and 27% of men had a sedentary lifestyle. High individual level ERI was associated with a higher likelihood of sedentary lifestyle both among women (odds ratio (OR) = 1.08, 95% CI 1.01 to 1.16) and men (OR = 1.17, 95% CI 1.02 to 1.33). These associations were not explained by relevant confounders and they were also independent of work unit level job strain measured as a ratio of job demands and control.

Conclusions

A mismatch between high occupational effort spent and low reward received in turn seems to be associated with an increased risk of sedentary lifestyle, although this association is relatively weak.     

Shift work increases the frequency of duodenal ulcer in H pylori infected workers

Aim

To evaluate whether shift work is associated with an increased rate of peptic ulcer in H pylori infected workers.

Methods

During a two year period, consecutive dyspeptic workers underwent non‐invasive evaluation of H pylori status by means of urea ¹³C breath test or stool testing. Those testing positive were included in the study and divided into two main categories: day‐time workers and shift workers. An upper gastrointestinal endoscopy was performed in all workers, and biopsy specimens were taken from the stomach to confirm the presence of H pylori infection (culture and histology).

Results

A total of 247 day‐time workers and 101 shift workers were included. The prevalence of duodenal ulcer was significantly higher in shift workers than in day‐time workers (29 of 101 v 23 of 247; OR = 3.92, 95% CI 2.13 to 7.21), and persisted after multivariate analysis, taking into account possible confounding factors (OR = 3.96, 95% CI 2.10 to 7.47).

Conclusion

Shift work increases the ulcerogenic potential of H pylori infection and should be considered a risk factor for duodenal ulcer in infected shift workers. Treatment of infection in this high risk group may improve the health of workers and may reduce the economic impact of peptic ulcer.     

Maternal and paternal occupational exposure to agricultural work and the risk of anencephaly

Aims

To evaluate the association between parental occupational exposure to agricultural work and the risk of anencephaly in three Mexican states.

Methods

A paired case control study (1:1) was done based on records of the Epidemiological Surveillance System of Neural Tube Defects in Mexico; 151 cases of anencephaly of more than 20 weeks'' gestation were selected between March 2000 and February 2001. Controls were selected from the same maternity services as those of the cases and were born alive without congenital malformations. Information was obtained from both parents by means of a general questionnaire, a food frequency questionnaire, and a specific questionnaire on occupational exposure to pesticides. Exposures were analysed with emphasis on the three months before and one month after the last menstruation periods (acute risk period (ARP)), as well as exposure prior to the abovementioned period (non‐acute risk period (NARP)).

Results

The children of mothers who worked in agriculture in the ARP had a greater risk of anencephaly (OR = 4.57, 95% CI 1.05 to 19.96). The risk of fathers having a child with anencephaly was greater in those who applied pesticides irrespective of whether it was done in the ARP or the NARP (OR = 2.50, 95% CI 0.73 to 8.64; and OR = 2.03, 95% CI 0.58 to 7.08, respectively).

Conclusions

These results support the hypothesis of the effect of maternal exposure to agricultural work on anencephaly and suggest that exposure of the father to pesticides in the periconceptional period or prior to this can also increase the risk of having an anencephalic child.     

Delta-aminolevulinic acid dehydratase polymorphism and the relation between low level lead exposure and the Mini-Mental Status Examination in older men: the Normative Aging Study

Objective

To determine whether a polymorphism the in δ‐aminolevulinic acid dehydratase (ALAD) gene modifies the neurotoxicity of lead in older adults.

Methods

The authors studied men participating in the Department of Veterans Affairs'' Normative Aging Study, assessing their recent exposure to lead by measuring blood lead (n = 915) at each triennial clinic visit, and, beginning in 1991, assessing their cumulative exposure by measuring lead levels in tibia (n = 722) and patella (n = 720), using K‐shell x ray fluorescence. Starting in 1993 and again at each triennial visit, the authors administered the Mini‐Mental State Examination (MMSE) to assess their cognitive functioning. The relation of the lead biomarkers to MMSE score was evaluated and this association was compared among men who carried the variant allele, ALAD‐2, versus men without the allele.

Results

Sixteen per cent of men carried the ALAD‐2 allele. Median tibia and patella lead levels (first‐third quartile) were 19 (13–28) and 27 (18–39) μg/g. Blood lead levels were consistent with non‐occupational exposure: only 6% of men had levels ⩾10 μg/dl. In multivariable adjusted analyses, higher levels of blood lead were associated with poorer performance on the MMSE. This association was most pronounced among ALAD‐2 carriers, among whom a 3 μg/dl increment in blood lead (the interquartile range) was associated with a 0.26 point lower mean MMSE score (95% CI −0.54 to 0.01), compared with a 0.04 point lower score (95% CI −0.16 to 0.07) among non‐carriers. The modest 0.22 point difference in these associations did not attain statistical significance, however (p_interaction = 0.13). The associations between bone lead levels and MMSE score did not vary by ALAD‐2 status.

Conclusions

Although not statistically significant, these findings suggest that ALAD genotype may modify blood lead''s adverse association with cognition among older men who had community exposures to lead. However, despite a relatively large sample size and the use of sensitive methods for measuring lead burden, the evidence overall was fairly weak.     

Intracerebral haemorrhage associated with hourly concentration of ambient particulate matter: case-crossover analysis

Aims

To examine the association of hourly time lagged concentration of ambient particulate matter and death due to stroke.

Methods

Mortality data for five years (January 1990 to December 1994) were obtained from the Ministry of Health, Labour, and Welfare of Japan. Data were used only if the deceased was 65 years old or older at the time of death, if death was attributed to intracerebral haemorrhage or ischaemic stroke, and if the deceased lived in one of 13 major urban areas. Hourly mean concentrations of PM7, NO₂, and photochemical oxidants were measured at monitoring stations in the 13 areas. Time stratified case‐crossover analysis was used to examine the data for evidence of triggering stroke mortality.

Results

The 1‐hour mean concentration of PM7 measured about 2 hours before death was associated with the risk of death due to intracerebral haemorrhage from April to September (odds ratio = 2.40, 95% CI 1.48 to 3.89, for exposure to PM7 of more than 200 μg/m³ (threshold)). The higher risk was independent of the 24‐hour mean concentration of PM7. PM7 was not associated with death due to ischaemic stroke.

Conclusions

Transiently high concentrations of PM7 are associated with death due to intracerebral haemorrhage. Air quality standards or guidelines for particulate matter should be based not only on 24‐hour mean concentrations, but also on hourly data.