Relative Sensitivity of Different Tests in the Detection of Low Titer Lupus Anticoagulants

Lupus anticoagulants (LA) and anticardiolipin antibodies have been strongly associated with recurrent abortion and fetal death. Because steroids have been reported to improve the fetal outcome of LA associated pregnancies, presumably by decreasing the levels of LA, it becomes desirable to have a simple and reliable test to monitor the levels of the putative antibody. To this effect, we assessed the capacity of the following coagulation tests to detect the presence of LA in serial dilutions of patient plasma with pooled normal plasma: kaolin clotting time (KCT), tissue thromboplastin inhibition test (TTIT), dilute Russell Viper venom time (DRVVT) and activated partial thromboplastin time with standard and high concentrations of phospholipids (SC and HCAPTT). All samples were also evaluated for the presence of anticardiolipin antibodies with an ELISA. The KCT was able to detect LA at a much greater dilution in normal plasma than any of the other clotting assays. The ELISA was comparable to KCT in its ability to detect high dilutions of LA.

Occupational exposure to endocrine disruptors and lymphoma risk in a multi-centric European study

BACKGROUND

Incidence rates of lymphoma are usually higher in men than in women, and oestrogens may protect against lymphoma.

METHODS

We evaluated occupational exposure to endocrine disrupting chemicals (EDCs) among 2457 controls and 2178 incident lymphoma cases and subtypes from the European Epilymph study.

RESULTS

Over 30 years of exposure to EDCs compared to no exposure was associated with a 24% increased risk of mature B-cell neoplasms (P-trend=0.02). Associations were observed among men, but not women.

CONCLUSIONS

Prolonged occupational exposure to endocrine disruptors seems to be moderately associated with some lymphoma subtypes.

Incidence and risk factors for inhibitor development in previously untreated severe haemophilia A patients born between 2005 and 2010

The objective of this study was to evaluate the inhibitor development (ID) in previously untreated patients (PUPs) with severe haemophilia A (FVIII ≤ 0.01 IU mL(-1) ). All Canadian Haemophilia Treatment Centres completed a questionnaire on patients born between September 2005 and August 2010 and followed for up to 7 years. Eligible patients had at least 20 exposure days (ED) or had developed an inhibitor. The odds ratio (OR) and 95% confidence intervals (95% CI) for risk factors to develop an inhibitor were estimated using unconditional logistic regression. A total of 99 haemophilia A PUPs were studied. Thirty-four (34%) developed an inhibitor (24/34 of high titre). Inhibitors developed in 25/63 (40%) patients with a high-risk mutation. ID was most frequent in Aboriginals (86%). Dose intensity (IU kg(-1)  day(-1) X number of ED) at first exposure to factor VIII (FVIII) was associated with a crude OR increase of 1.10 (95% CI: 0.99-1.23) with each increase of 100 dose-intensity units. Haemarthrosis and intracranial bleeding as the indication for first exposure to FVIII concentrate were associated with a crude OR for ID of 7.63 (95% CI: 2.14-27.17) and 5.08 (95% CI: 1.11-23.31) respectively. ID according to FVIII concentrate used was: Advate (®) 18/50 (36%), Kogenate FS(®) or Helixate FS(®) 15/36 (42%), Wilate(®) 0/11 and Xyntha(®) 1/2. In multivariate analysis, Aboriginal ethnicity (OR = 11.69; 95% CI: 1.11-122.86) and haemarthrosis (OR = 4.49; 95% CI: 1.08-18.61) were statistically significant. The cumulative incidence of ID in severe haemophilia A PUPs was 34% and varied according to ethnicity, type of bleeding at first ED, type of FVIII product and dose intensity at first exposure.

Continuing utilisation of specialised health services in extremely preterm infants

OBJECTIVE

To compare healthcare use from neonatal discharge to 18 months corrected age (CA) of two groups of extremely preterm neonates (23-25 vs 26-28 weeks).

DESIGN

Cohort study.

PATIENTS

Infants born at < or =28 weeks and admitted in three hospital centres in Quebec, Canada (n=254).

MAIN OUTCOME MEASURES

Neurodevelopmental outcomes and healthcare use from neonatal discharge to 18 months CA.

RESULTS

Re-hospitalisation rates occurred in 57% of children born at 23-25 weeks and in 49% of those born at 26-28 weeks. In these two age groups, by 18 months, 61% vs 59% were followed in physical or occupational therapy, 29% vs 17% were enrolled in a long-term rehabilitation program, 38% vs 28% used prescribed medication, and 59% vs 33% required medical assistive devices, respectively. Risk of re-hospitalisation was related to bronchopulmonary dysplasia (BPD), severe brain injury, use of home oxygen or an apnoea monitor and older age at neonatal discharge. Multiple births, BPD, severe brain injury, older age at neonatal discharge and single parenthood were associated with risk of using out-patient health services above average (>2 services).

CONCLUSION

Extremely preterm children are frequently re-hospitalised during infancy and use a substantial amount of healthcare resources. These results highlight the importance of resource allocation to preterm infants for medical and rehabilitation services after discharge from the neonatal intensive care unit.

Peanut allergy: is maternal transmission of antigens during pregnancy and breastfeeding a risk factor?

BACKGROUND

Peanut allergy is an important public health problem in western countries. However, the risk factors associated with this allergy remain uncertain.

OBJECTIVE

To determine whether the consumption of peanuts during pregnancy and breastfeeding is a risk factor for peanut allergy in infants.

METHODS

We enrolled 403 infants in a case-control study. The cases were infants aged 18 months or less with a diagnosis of peanut allergy based on a history of clinical reaction after exposure to peanuts and the presence of peanut-specific immunoglobulin E. Controls were age-matched infants with no known clinical history or signs of atopic disease. The mothers of the children filled out a detailed questionnaire about maternal diet during pregnancy and breastfeeding, the infant's diet, the presence of peanut products in the infant's environment, and family history of atopy.

RESULTS

The mean (SD) age of cases was 1.23 (0.03) years. The groups were comparable in terms of the rate and duration of breastfeeding. However, the reported consumption of peanuts during pregnancy and breastfeeding was higher in the case group and associated with an increased risk of peanut allergy in offspring (odds ratio [OR], 4.22 [95% confidence interval [CI], 1.57-11.30 and OR, 2.28 [95% CI, 1.31-3.97] for pregnancy and breastfeeding, respectively). Overall, the infants with peanut allergy did not seem to be more exposed to peanut products in their environment than the controls.

CONCLUSION

Early exposure to peanut allergens, whether in utero or through human breast milk, seems to increase the risk of developing peanut allergy.

Indoor ultrafine particles and childhood asthma: exploring a potential public health concern

Exposure to airborne particulate matter has a negative effect on respiratory health in both children and adults. The ultrafine fraction of particulate air pollution is of particular interest because of its increased ability to cause oxidative stress and inflammation in the lungs. We reviewed the literature, and to date findings suggest that ultrafine particles (UFPs) may play an important role in triggering asthma symptoms. Furthermore, we believe that indoor UFP exposures may be particularly important because people spend the majority of their time indoors where sources of these contaminants are often present. While several epidemiological studies have examined the respiratory effects of ambient UFP exposures, the relationship between indoor UFP exposures and childhood asthma has yet to be examined in clinical or epidemiological studies. However, the portable instrumentation necessary to conduct such investigations is increasingly available, and we expect that this issue will be addressed in the near future. Therefore, the aim of this article is to provide a general review of UFP toxicity as related to childhood asthma in order to draw attention to a potentially important public health concern.

PRACTICAL IMPLICATIONS

A number of indoor sources of ultrafine particles (UFPs) have been identified, but the health effects of indoor UFP exposures remain largely unexplored. The potential respiratory effects of such exposures seem most concerning because these particles are known to cause oxidative stress and inflammation in the lungs. Subsequently, indoor UFP exposures may contribute to the exacerbation of asthma symptoms in susceptible individuals. This paper provides a review of UFP toxicity as related to childhood asthma, and to date evidence suggests that further investigation into the respiratory effects of indoor UFP exposures is warranted.

Is metal fume fever a determinant of welding related respiratory symptoms and/or increased bronchial responsiveness? A longitudinal study

BACKGROUND

The current prospective study investigated the hypothesis of metal fume fever (MFF) being a predictor for the development of respiratory symptoms and functional abnormalities.

METHODS

The study consisted of a pre-exposure and two follow up assessments of 286 welding apprentices during an average period of 15 months. A respiratory and a systemic symptom questionnaire, skin prick tests to common allergens and metal salts, spirometry, and methacholine challenge tests were administered.

RESULTS

Developing at least one positive skin prick test to a metallic salt solution was found in 11.8% of apprentices. Possible MFF (at least one of fever, feelings of flu, general malaise, chills, dry cough, metallic taste, or shortness of breath) was reported by 39.2% of apprentices. The presence of at least one welding related respiratory symptom (cough, wheezing, or chest tightness) suggestive of welding related asthma was reported by 13.8%. MFF was significantly associated with these respiratory symptoms (OR = 4.92, 95% CI 2.10 to 11.52), after adjusting for age, atopy, smoking, physician diagnosed asthma, and symptoms of non-welding related asthma. Apprentices with possible MFF, and no welding related respiratory symptoms suggestive of welding related asthma at the first follow up, had an increased risk of developing the latter symptoms by the second follow up visit (OR = 7.4, 95% CI 1.97 to 27.45) compared with those not having MFF. MFF was not significantly associated with an increase in bronchial responsiveness.

CONCLUSION

MFF could be a predictor for the development of respiratory symptoms but not for functional abnormalities in welders.

Incidence of probable occupational asthma and changes in airway calibre and responsiveness in apprentice welders

The majority of cross-sectional studies have shown a higher prevalence of ventilatory impairment in welders while only few longitudinal studies were able to detect chronic effects on spirometry or bronchial responsiveness. The aim of the study was to determine the incidence of probable occupational asthma (OA), bronchial obstruction and hyperresponsiveness among 286 students entering an apprenticeship programme in the welding profession. This epidemiological prospective cohort study consisted of a baseline assessment survey and two follow-up assessments. A respiratory symptom questionnaire was administered at each visit. Spirometry and methacholine bronchial challenge test results, conducted once prior to onset of exposure and later after an average of 15 months of apprenticeship, were available for 194 subjects. The incidence of probable OA was approximately 3% (6 of 194). The incidence of bronchial hyperresponsiveness, defined as a > or = 3.2-fold decrease in the provocative concentration causing a 20% fall in the forced expiratory volume in one second from baseline to the end of the study was 11.9%. A statistically significant difference was found between the baseline and end of study for the lung function values. In particular, the forced expiratory volume per cent predicted had significantly dropped by 8.4% on average. The significance of these early pulmonary function changes in relation to possible chronic effects of exposure to welding fumes and gases remains to be explored.

Prevalence and association of welding related systemic and respiratory symptoms in welders

BACKGROUND

The prevalence of welding related respiratory symptoms coexisting with welding related systemic symptoms in welders is unknown.

AIMS

To determine in a sample of welders the prevalence of coexisting welding related systemic symptoms indicative of metal fume fever (MFF) and welding related respiratory symptoms suggestive of occupational asthma (OA), and the strength and significance of any association between these two groups of symptoms.

METHODS

A respiratory symptoms questionnaire, a systemic symptoms questionnaire, and a questionnaire on occupational history were administered by telephone to 351 of a sample of 441 welders (79.6%) from two cities in Québec, Canada.

RESULTS

The co-occurrence of possible MFF (defined as having at least two symptoms of fever, feelings of flu, general malaise, chills, dry cough, metallic taste, and shortness of breath, occurring at the beginning of the working week, 3-10 hours after exposure to welding fumes) together with welding related respiratory symptoms suggestive of OA (defined as having at least two welding related symptoms of cough, wheezing, and chest tightness) was 5.8%. These two groups of symptoms were significantly associated (chi(2) = 18.9, p < 0.001).

CONCLUSION

There is a strong association between welding related MFF and welding related respiratory symptoms suggestive of OA. As such, MFF could be viewed as a pre-marker of welding related OA, a hypothesis that requires further investigation.

Reference values for an index of fetal aortic isthmus blood flow during the second half of pregnancy

OBJECTIVE

During fetal life, the parallel position of the two cardiac ventricles confers a special status to the aortic isthmus. Flow through the isthmus reflects the balance between the performances of the two ventricles and their respective peripheral impedances. This study proposes a fetal aortic isthmus flow velocity index and its reference values defined on the basis of gestational age (GA).

METHODS

Video recordings of 111 normal fetuses from 18 to 39 weeks of gestation were retrospectively reviewed. An isthmus flow velocity index (IFI) was calculated as follows: IFI = (systolic + diastolic)/systolic velocity integrals. GA-specific reference ranges of IFI were constructed.

RESULTS

An IFI of 1.33 +/- 0.03 was found at 18 weeks. This value decreased slightly but steadily with GA to reach 1.23 +/- 0.16 at 39 weeks. This change is mainly related to a decrease in diastolic velocity integrals.

CONCLUSION

The proposed IFI provides information on the direction and, indirectly, on the volume of blood flow through the fetal aortic isthmus.

Incidence and host determinants of work-related rhinoconjunctivitis in apprentice pastry-makers

BACKGROUND

The authors recently assessed the incidence and determinants of immunologic sensitization to flour in apprentice pastry-makers. The aim of this work was to determine the incidence of work-related rhinoconjunctivitis (RC) symptoms and their determinants.

METHODS

For this 188/230 entrants (81.7%) were evaluated before starting exposure to flour, and again 10.8 and 16.8 months after. Questionnaires and skin prick testing to common and work-related allergens were administered at each visit. Bronchial responsiveness to methacholine was assessed at baseline in all subjects and in a subgroup at follow-up.

RESULTS

Thirty subjects (16.1%) reported new work-related RC symptoms (13.1 per 100 person-years); in three subjects (1.6%), these were accompanied by incident skin prick test reactivity to flour-derived allergens. Skin prick test reactivity to grass pollens (OR = 3.0, 95% CI, 1.3-6.7) and to pets (OR = 2.5, 95% CI, 1.1-5.9), persistent rhinitis (OR = 3.1, 95% CI, 1.1-8.4), seasonal RC (OR = 2.5, 95% CI, 1.1-5.5), RC on contact with pets (OR = 2.3, 95% CI, 1.03-5.0) and skin prick test reactivity to wheat flour (OR = 10.5, 95% CI, 2.3-46.8), assessed at baseline, were significantly associated with the incidence of work-related RC symptoms. Multivariate logistic regression analysis yielded significant OR of skin prick test reactivity to wheat flour at baseline (OR = 7.1, 95% CI, 1.7-35.1) and persistent rhinitis (OR = 3.9, 95% CI, 1.01-9.6) for the incidence of work-related RC symptoms. Increased bronchial hyperresponsiveness at follow-up was more frequent, although not significantly, in subjects positive to skin prick test to flour on entry and reporting new work-related symptoms (3/5), than in other subjects (4/17).

CONCLUSIONS

The incidence of work-related RC symptoms among apprentice pastry-makers was high (16.1% 30/186), while a minority (3/30) also developed skin prick test reactivity to flour. Skin prick test reactivity to wheat flour and persistent allergic rhinitis on starting exposure to flour are significant determinants for the development of work-related RC symptoms.

Effectiveness of the hands-free technique in reducing operating theatre injuries

BACKGROUND

Operating theatre personnel are at increased risk for transmission of blood borne pathogens when passing sharp instruments. The hands-free technique, whereby a tray or other means are used to eliminate simultaneous handling of sharp instruments, has been recommended.

AIMS

To prospectively evaluate the effectiveness of the hands-free technique in reducing the incidence of percutaneous injuries, contaminations, and glove tears arising from handling sharp instruments.

METHODS

For each of 3765 operations carried out in main and surgical day care operating theatres in a large urban hospital, over six months, circulating nurses recorded the proportion of use of the hands-free technique during each operation, as well as other features of the operation. The hands-free technique, considered to be used when 75% or more of the passes in an operation were done in this way, was used in 42% of operations. The relative rate of incidents (percutaneous injuries, contaminations, and glove tears) in operations where the hands-free technique was used and not used, with adjustment via multiple logistic regression for the different risk profiles of the two sets of operations, was calculated.

RESULTS

A total of 143 incidents (40 percutaneous injuries, 51 contaminations, and 52 glove tears) were reported. In operations with greater than 100 ml blood loss, the incident rate was 4% (18/486) when the hands-free technique was used and 10% (90/880) when it was not, approximately 60% less. When adjusted for differences in type and duration of surgery, emergency status, noisiness, time of day, and number present for 75% of the operation, the reduction in the rate was 59% (95% CI 23% to 72%). In operations with less than 100 ml blood loss, the corresponding rates were 1.4% (15/1051) when the hands-free technique was used and 1.5% (19/1259) when it was not used. Adjustment for differences in risk factors did not alter the difference.

CONCLUSIONS

Although not effective in all operations, use of the hands-free technique was effective in operations with more substantial blood loss.

Exposure to formaldehyde among animal health students

The objective of the present study was to evaluate the exposure to formaldehyde in 2 groups each with 18 students in animal health technology from two different training centers (TC) during a 3-hour weekly laboratory session in biology. Personal sampling during the session was done with passive bubblers for formaldehyde. The analysis of formaldehyde was done by visible absorption spectrometry according to NIOSH method 3500. The students in TC 1 were exposed to formaldehyde levels ranging from less than 0.11 to 0.76 mg/m3 with an average at 0.25 mg/m3 during the 3-hour biology laboratory. The students in TC 2 were exposed to higher concentrations of formaldehyde ranging from 0.26 to 1.2 mg/m3 with an average at 0.632 mg/m3. The results of the survey indicate that the students in both centers were exposed to a notable amount of formaldehyde vapor, at a level that is above the threshold limit value.

Individual estimation of exposures to extremely low frequency magnetic fields in jobs commonly held by women

Exposures to extremely low frequency (ELF) magnetic fields have not been documented extensively in occupations besides the work environments of electric or telephone utilities. A 1980-1993 study of childhood acute lymphoblastic leukemia (ALL) in Québec, Canada, gathered detailed information about the occupations of 491 mothers of ALL cases and mothers of a similar number of healthy controls. This information was combined with published data on the intensities of ELF magnetic fields associated with sources or work environments to estimate ELF magnetic field exposures for a wide range of jobs commonly held by women. Estimated exposures for 61 job categories ranged from 0.03 to 0.68 microT; the 25th, 50th, and 75th percentiles were 0.135, 0.17, and 0.23 microT, respectively. By job category, the most highly exposed jobs (>0.23 microT) included bakery worker, cashier, cook and kitchen worker, electronics worker, residential and industrial sewing machine operator, and textile machine operator. By work environment, the most highly exposed job categories were electronics worker in an assembly plant (0.70 microT) and sewing machine operators in a textile factory (0.68 microT) and shoe factory (0.66 microT). These results provide new information on expected levels of exposure in a wide range of jobs commonly held by women.

Host determinants for the development of allergy in apprentices exposed to laboratory animals

The aim of this study was to evaluate whether determinants of work-related symptoms, skin sensitization and diseases differ between atopic and nonatopic subjects starting a career with exposure to laboratory animals (LA). A cohort of 417 apprentices in animal-health technology was prospectively followed during 32 or 44 months. The effect on the study outcomes of variables derived from questionnaire, skin reactivity, and lung function assessments at baseline were compared in atopic (n=212) and nonatopic (n=183) subjects. Eighty-five incident cases of sensitization to a LA-derived allergen were identified, 67 among atopic and 18 among nonatopic subjects. Baseline rhinitis symptoms in contact with pets and skin sensitization to pets were associated with the development of work-related rhinoconjunctivitis (RC) symptoms in atopic subjects, whereas perannual rhinitis symptoms and having a PC20 (provocative concentration causing a 20% fall in forced expiratory volume in one second) < or = 32 mg x mL(-1) were associated in nonatopic subjects. Baseline rhinitis symptoms on contact with pets and a PC20 value < or = 32 mg x mL(-1) were significant determinants for developing sensitization to a specific allergen in atopic subjects only. Finally, baseline rhinitis symptoms in contact with pets and perannual rhinitis symptoms were associated with the development of occupational RC in atopic subjects, whereas in nonatopic subjects this was associated with having a PC20 value < or = 32 mg x mL(-1). In conclusion, the determinants for the development of specific skin sensitization, symptoms and disease are different between atopic and nonatopic apprentices starting occupational exposure to laboratory-animal-derived allergens.

[Investigation of fetal arrhythmias by simultaneous recording of ascending aortic and superior vena caval blood flow]

In a period of 18 consecutive months, all the foetus referred to our Foetal Cardiology Unit for investigation of arrhythmia were systematically assessed by M mode echocardiography and simultaneous recording of blood flow in the superior vena cava and the aorta (SVC/Ao). This study was undertaken to compare the performance of these two approaches. The foetus were classified into three groups according to the arrhythmia diagnosed: Group 1: irregular arrhythmias, Group 2: bradycardias, Group 3: tachycardias. A surface ECG was recorded in all the neonates in whom the arrhythmias persisted. In Group 1, including 50 cases of extrasystoles (49 atrial and 1 ventricular), M mode echo and the Doppler provided the diagnosis in 42 and 47 cases respectively. This difference was not statistically significant. Group 2 comprised four cases of bradycardia (2 blocked atrial bigeminy, 2 complete atrioventricular blocks); the two methods provided the diagnosis in all 4 cases. Group 3 comprised 11 cases including 7 supraventricular tachycardias (SVT), 2 flutter, 1 chaotic atrial rhythm and 1 ectopic junctional rhythm. Complete analysis of these arrhythmias was possible by M mode in 4 cases and by Doppler in all cases. This difference was significant. The distribution of the 7 cases of SVT with respect to the duration of the ventriculoatrial interval was possible by M mode in 2 cases and in all cases by Doppler. This was a decisive factor in the choice of antiarrhythmic therapy. The authors conclude that Doppler and M mode are two echocardiographic approaches which are equally effective in the investigation of foetal atrial extrasystoles and probably of sustained foetal bradycardia. However, Doppler recording of SVC/Ao gives a more detailed and precise diagnosis of more complex foetal arrhythmias.

Quantifying and reducing the risk of bloodborne pathogen exposure

The risk of becoming infected with bloodborne pathogens (e.g., hepatitis B, hepatitis C, HIV) during surgery is real. The degree of risk for perioperative personnel is related to factors that include participating in large numbers of surgical procedures each year; the nature of perioperative work (e.g., use of different types of sharp instruments): exposure to large amounts of blood and body fluids; the prevalence of bloodborne pathogens in the surgical population; the variation in different organisms' ability to be transmitted; the existence of vaccines and the level of vaccination; the availability of postexposure treatment; and the consequences of acquiring the disease. Controlling risks to perioperative personnel can be accomplished by using the Occupational Safety and Health Administration's three methods of control--redesigning surgical equipment and procedures, changing work practices, and enhancing the personal protection equipment of perioperative personnel.

Natural history of sensitization, symptoms and occupational diseases in apprentices exposed to laboratory animals

The natural history of the development of sensitization and disease due to high-molecular-weight allergens is not well characterized. This study describes the time-course of the incidence of work-related symptoms, skin reactivity and occupational rhinoconjunctivitis (RC) and asthma (OA); and assesses the predictive value of skin testing and RC symptoms in apprentices exposed to laboratory animals, in a 3-4-yr programme. Four-hundred and seventeen apprentices at five institutions were assessed prospectively with questionnaire, skin-testing with animal-derived allergens, spirometry and airway responsiveness (n=373). Depending on the school, students were seen 8 (n=136), 20 (n=345), 32 (n=355) and 44 (n=98) months after starting the programme. At all visits, the incidence was greater for work-related RC symptoms followed in order by skin reactivity, occupational RC, and, almost equally, OA and work-related respiratory symptoms. The incidence-density figures were comparable for each follow-up period and for most indices up to 32 months after entry into the study and then tended to decrease. The positive predictive values (PPVs) of skin reactivity to work-related allergens for the development of work-related RC and respiratory symptoms were 30% and 9.0%, respectively, while the PPVs of work-related RC for the development of OA was 11.4%. Sensitization, symptoms and diseases occur maximally in the first 2-3 yrs after starting exposure to laboratory animals. Skin reactivity to work-related allergens and rhinoconjuctivitis symptoms have low positive predictive values.

Incidence of sensitization, symptoms, and probable occupational rhinoconjunctivitis and asthma in apprentices starting exposure to latex

Latex is a well-known sensitizer. Prospective studies in apprentices beginning to be exposed to latex have not been carried out. We wanted to determine the incidence of skin reactivity, cutaneous symptoms, rhinoconjunctivitis (RC) symptoms, respiratory symptoms, probable occupational RC, and asthma in apprentices in dental hygiene. A total of 122 students starting a program in dental hygiene technology were recruited between 1993 and 1995. A questionnaire, skin-prick tests with common aeroallergens and latex, and assessment of spirometry and responsiveness to methacholine were carried out on entry and at follow-up visits at 20 and 32 months after the start of exposure. Of the 110 subjects who participated for at least 1 follow-up visit, skin reactivity to latex developed in 7. Cutaneous symptoms developed in 6 of the 7, RC symptoms developed in 2, and respiratory symptoms developed in 1. Five of the 7 subjects had significant changes in methacholine responsiveness and fulfilled the definition of probable occupational asthma. Sensitized subjects were more likely to be atopic and to have a previous history of asthma and respiratory symptoms on exercise than were nonsensitized subjects. Three subjects at the 20-month assessment and 4 subjects at the 32-month visit showed skin reactivity. The cumulative incidences for skin sensitization, probable occupational RC, and occupational asthma to latex were 6.4%, 1.8%, and 4.5%, respectively.

Family size, day-care attendance, and breastfeeding in relation to the incidence of childhood asthma

A hypothesis has been suggested stating that children exposed early to infections are less likely to develop atopy or asthma. The authors investigated the relation between risk of childhood asthma and number of siblings as well as day-care attendance, as factors possibly increasing the likelihood of early infections, and breastfeeding as a factor reducing them. A case-control study was carried out in Montréal, Canada, between 1988 and 1995 that included 457 children diagnosed with asthma at 3--4 years of age and 457 healthy controls. Cases followed for 6 years were later classified as persistent or transient by the symptoms and use of medication after diagnosis. Among cases diagnosed at 3--4 years of age, the adjusted odds ratio for asthma was 0.54 (95% confidence interval (CI): 0.36, 0.80) for one sibling and 0.49 (95% CI: 0.30, 0.81) for two or more. The adjusted odds ratio for day-care attendance before 1 year of age was 0.59 (95% CI: 0.40, 0.87). Results were similar with persistent cases. Among transient cases (who possibly had an infection with wheezing at 3--4 years of age), day-care attendance and a short duration of breastfeeding resulted in increased risk. The results support the hypothesis that opportunity for early infections reduces the risk of asthma.

Congenital anomalies in children with acute lymphoblastic leukaemia and in their family

BACKGROUND

With the exception of Down syndrome the association between congenital anomalies and acute lymphoblastic leukaemia (ALL) is presently unclear. We investigated this association in a population-based case-control study carried out in the province of Québec, CANADA:

METHODS

A total of 491 incident cases diagnosed between 1980 and 1993 and aged 0-9 years were included in the study. Healthy controls (n = 491) matched on age, sex, and region of residence at the time of diagnosis were selected from government family allowance files. Using a structured questionnaire and the International Classification of Diseases (Ninth Revision) list of congenital anomalies, presence of an anomaly was determined by interviewing the parents of the study subjects; mothers gave information on anomalies in the study subject, their siblings and her family, whereas fathers provided information on anomalies in their family.

RESULTS

The adjusted risk for ALL was not increased in children who had any anomaly (odds ratio [OR] = 1.07 [95% CI : 0.70-1.65]) whereas compared to control siblings, case siblings had a higher risk of anomalies (OR = 1.54, 95% CI : 0.99- 2.42). This increase was likely due to excesses in anomalies of the heart (OR = 2.49, 95% CI : 1.23-5.04). Risk for ALL was elevated in children with a history of a congenital anomaly in their mother (OR = 1.61, 95% CI : 0.80-3.22) or her family (OR = 1.45, 95% CI : 0.94-2.25).

CONCLUSIONS

Although based on small numbers for specific anomalies, these findings suggest that congenital anomalies are more prevalent in siblings and maternal family of ALL cases than in controls.

Incidence and host determinants of probable occupational asthma in apprentices exposed to laboratory animals

Laboratory animal (LA) workers are frequently affected with allergic sensitization and occupational asthma (OA). The role of preexposure host factors, in particular airway responsiveness, on the incidence of OA has not been satisfactorily studied. A prospective cohort study of 417 apprentices in animal-health technology was conducted to investigate the incidence and determinants of probable OA. Questionnaire and skin-prick tests with common and work-specific allergens were administered on entry and at follow-up visits (up to three) from 8 to 44 mo after starting apprenticeship. Responsiveness to inhaled methacholine was assessed at baseline and at follow-up in apprentices who developed a new specific skin sensitization and in control subjects. Preexposure host characteristics and the school attended were compared between cases and all cohort subjects not meeting the criteria for probable OA. Twenty-eight apprentices satisfied the definition for probable OA, i.e., onset of immediate skin reactivity to > 1 occupational inhalant and > 3.2-fold decrease in the provocative concentration causing a 20% reduction in FEV(1) (PC(20)). The incidence of probable OA was 2.7% (28/1,043 person-years). Baseline immediate skin reactivity to pets (rate ratio [RR] 4.1, 95% confidence interval [CI] = 1.6 to 10.8), and bronchial responsiveness (PC(20) < or = 32 versus PC(20) > 32 mg/ ml) (RR = 2.5, 95% CI = 1.0 to 5.8) were associated with an increased risk of probable OA; a lower FEV(1) had an apparent, protective effect (RR = 0.58, 95% CI = 0.43 to 0.78). It is concluded that apprentices in animal health show a high incidence of probable OA, and that preexposure airway caliber and responsiveness as well as sensitization to pets are associated with an increased risk.

Correlation between prenatal velocity waveforms in the aortic isthmus and neurodevelopmental outcome between the ages of 2 and 4 years

OBJECTIVE

Experimental studies on fetal lambs have shown that during an increase in the resistance to placental flow the delivery of oxygen to the brain is preserved as long as net flow through the aortic isthmus is antegrade. Our purpose was to determine whether the same changes in aortic isthmus flow in human subjects have any impact on neurodevelopmental outcome.

STUDY DESIGN

Forty-four fetuses were retrospectively included in this study on the basis of an abnormal Doppler velocity in the umbilical artery. Mean gestational age at delivery was 33.0 +/- 2.0 weeks and mean birth weight 1386 +/- 435 g. The neurodevelopmental condition was assessed between the ages of 2 and 4 years. The developmental score was analyzed in relation to the flow patterns in the fetal aortic isthmus, which were classified as follows: group A, net isthmic flow antegrade (defined as the ratio of the systolic antegrade to the diastolic retrograde velocity integrals) (n = 39); group B, net isthmic flow retrograde (n = 5).

RESULTS

Nonoptimal neurodevelopment was observed in 19 (49%) of 39 fetuses in group A and in all 5 fetuses (100%) in group B. This difference is significant and leads to a relative risk of 2.05 (95% confidence interval, 1.49-2.83) for neurodevelopmental deficit when predominantly retrograde flow is observed in the fetal aortic isthmus before birth.

CONCLUSION

Measuring the ratio of antegrade to retrograde velocity integrals in the aortic isthmus could help in the indirect assessment of cerebral oxygenation during placental circulatory insufficiency.

Drinking water contaminants and childhood leukemia

We conducted a population-based case-control study to evaluate the relation between exposure to drinking water contaminants (total and specific trihalomethanes and certain metals and nitrates) and childhood acute lymphoblastic leukemia. We compared 491 cases 0-9 years of age with 491 controls. We developed a municipality-exposure matrix based on municipal and provincial historical data, a tapwater survey in 227 homes, and information about residential history. We used average level of exposure and cumulative average over the period as exposure indices, and we measured risk for the pregnancy period as well as for the postnatal period. We show that risks were generally not increased for the prenatal period nor with average levels of exposure. Postnatal cumulative exposure for total trihalomethanes at above the 95th percentile of the distribution for cases and controls was associated with an odds ratio of 1.54 (95% confidence interval = 0.78-3.03); for that same period, risk associated with exposure to chloroform was increased (odds ratio = 1.63; 95% confidence interval = 0.84-3.19) as well as that for exposure to zinc (odds ratio = 2.48; 95% confidence interval = 0.99-6.24). Risks were also increased for exposure to cadmium and arsenic, but not for other metals nor for nitrates.

Markers of infection, breast-feeding and childhood acute lymphoblastic leukaemia

Infections are suspected to play a role in the aetiology of childhood leukaemia. In 1989-95, we evaluated the relation between childhood acute lymphoblastic leukaemia and pre- and postnatal markers of exposure to infection, as well as breast-feeding. A population-based case-control study was carried out in certain regions of Québec, Canada, in 1989-95 including 491 incident cases diagnosed between 1980 and 1993 and aged between 0 and 9 years. An identical number of healthy controls matched for age, sex and region of residence at the date of diagnosis was included. Having older siblings, mother's use of antibiotics during pregnancy, and being born second or later were all associated with increased risk of leukaemia while early day-care attendance (odds ratio (OR) = 0.49; 95% CI 0.31-0.77), and breast-feeding (OR = 0.68; 95% CI 0.49-0.95) were significantly protective. A marker of population mixing was not a risk factor. When including all variables defining family structure in a model, having older siblings at time of diagnosis was a risk factor among children diagnosed before 4 years of age (OR = 4.54; 95% CI 2.27-9.07) whereas having older siblings in the first year of life was protective among children diagnosed at 4 years of age or later (OR = 0.46; 95% CI 0.22-0.97).

Incidence and determinants of IgE-mediated sensitization in apprentices. A prospective study

We investigated prospectively the incidence and determinants of work-related specific skin sensitization in a cohort of 769 apprentices, including 417 in animal health technology, 230 in pastry-making, and 122 in dental-hygiene technology. Subjects were recruited when starting exposure to laboratory animals, flour, or latex. A questionnaire and skin-prick tests with common and work-related allergens were administered on entry and at follow-up visits from 8 to 44 mo; information on number of hours of exposure to specific allergens was obtained. Among 769 apprentices, 698 attended >/= 1 follow-up visit. A total of 111 subjects developed specific sensitization over the study period. The incidence of work-related sensitization (per person-year) was 8.9% (95% CI 7.3 to 11.0%) in the animal-health program, 4.2% (95% CI 1.8 to 8.2%) in the pastry-making program, and 2.5% (95% CI = 0.7 to 4.3%) in the dental-hygiene program. In the animal health group, Cox regression analyses showed that atopy, nasal, and respiratory symptoms in the pollen season, and exposure assessed by the school attended or by duration of exposure to rodents were the most significant predictors of sensitization. In the dental-hygiene program, atopy and asthma were significant determinants. This study shows that: (1) an apprenticeship in animal-health technology carries a greater risk of developing specific sensitization than do apprenticeships in pastry-making and dental-hygiene; (2) atopy, respiratory symptoms in the pollen season, and number of hours in contact with rodents determine the risk of sensitization in apprentices in the animal health program.

Empirical study of parental recall bias

Recall bias is a major concern in case-control studies in which questionnaire data are used to assess past exposure. The authors conducted a validation substudy within the framework of a parent case-control study on risk factors for acute lymphoblastic leukemia in children aged < or =9 years diagnosed in 1980-1993 in Quebec, Canada. Parental recall bias for two variables was assessed: reported distance from home to power lines compared with measured distance and reported prenatal radiographic examinations compared with hospital medical record data. For reported distance, sensitivity was 62% for a subgroup of cases living in an area in which an excess of childhood acute lymphoblastic leukemia was perceived and was attributed to power lines. However, for other cases, sensitivity (35%) was similar to that measured for hospital controls (36%) and was relatively close to that for population controls (22%). Specificity was high for all groups except cases from the area with a perceived excess. Sensitivity for reported prenatal radiographic examinations was similar for cases (64%) and population controls (71%) but was lower for hospital controls (50%). Results confirm that under special circumstances, such as those resulting from enhanced public concern, parental recall can be differential but otherwise is most often nondifferential, with low sensitivity. Choosing the best type of controls to ensure comparable recall accuracy remains difficult.

Parental smoking, CYP1A1 genetic polymorphisms and childhood leukemia (Québec, Canada)

OBJECTIVE

To evaluate the effect of parental smoking on childhood acute lymphoblastic leukemia and to determine if it is modified by child genetic polymorphisms.

METHODS

We carried out a case-control study in Quebec, Canada, including 491 incident cases aged 0-9 years and as many healthy controls matched on age and sex. Each parent was interviewed separately with respect to smoking habits during and after pregnancy. In addition, we carried out a case-only substudy with 158 cases classified according to presence or absence of the alleles *2A, *2B, and *4 in the CYP1A1 gene.

RESULTS

There were small risk increases with maternal smoking during the later trimesters. Interaction odds ratios were increased (although often not significantly) for the CYP1A1*4 allele at high levels of maternal smoking in the last trimesters and at low level of paternal postnatal smoking, and decreased for the CYP1A1*2B allele. The latter appeared to confer a protective advantage at low levels for maternal prenatal smoking and at high levels for paternal postnatal smoking.

CONCLUSIONS

Reported smoking habits showed no association with leukemia; risks for genetic polymorphisms lacked precision but indicated that the effect of parental smoking could be modified by variant alleles in the CYP1A1 gene.

Risk of childhood leukemia associated with diagnostic irradiation and polymorphisms in DNA repair genes

The purpose of the study was to measure risk of childhood acute lymphoblastic leukemia associated with reported postnatal diagnostic X rays and to determine if it was modified in the presence of variants in genes involved in DNA repair. We conducted a population-based case-control study with 491 cases and 491 healthy controls among children 0-9 years of age at diagnosis. To evaluate gene-environment interaction, we used a subgroup of 129 cases. The adjusted odds ratio (OR) for one reported postnatal child X ray versus none was 1.04 [95% confidence interval (CI), 0.72-1.49], whereas the OR for two or more X rays was 1.61 (CI, 1.13-2.28). Among girls, the former ORs were 1.14 (CI, 0.66-1.96) and 2.26 (1. 20-4.23), respectively. Among girls who carried the hMSH3 [exon (ex) 23] variant, the ORs were 3.33 (CI, 0.75-14.82) for one X ray and 0. 27 (CI, 0.05-1.57) for two or more X rays, whereas among those who carried the XRCCI (ex 6) variant, the ORs were 1.45 (0.11-19.08) and 6.66 (0.78-56.63), respectively. On the other hand, at low levels of exposure, boys seemed protected by the variant hMLH1 (ex 8). The latter results must be interpreted with caution but suggest that the effect of diagnostic X rays could be modified by variants in repair genes according to sex. Few studies have evaluated the risk of postnatal diagnostic irradiation, which was moderately strong here; we are not aware of any studies that also considered the effect of polymorphisms in DNA repair genes. Based on the present results, both aspects deserve further study.

Individual characteristics and quitting in apprentices exposed to high-molecular-weight agents

To determine whether specific immunological sensitization (SIS) and symptoms of allergy are associated with quitting apprenticeships with exposure to high-molecular-weight (HMW) agents. In a cohort study of 769 apprentices starting career programs in animal health technology (AHT), pastry-making (PM), and dental hygiene technology (DHT), health status was assessed at baseline and yearly for up to 44 mo. Subjects who quit the apprenticeship were contacted and offered a last series of measurements as if they pursued. The effect of various factors-at baseline and during the career program-on quitting was examined. Eighty-nine of 769 subjects (11.6%) quit, of whom 74 participated in this study. In multivariate analysis, a history of hay fever (OR = 1.66, 95% CI = 1.0 to 2.75) and attending the pastry-making program (OR = 2.33, 95% CI = 1.11 to 4.91) were significant determinants for quitting. In the subgroup of AHT, SIS to laboratory animals, hay fever, and shortness of breath were significant determinants by univariate analysis; in PM, the only determinant was age; and in DHT, hay fever. Work-related symptoms during training were not associated with quitting. In a multivariate logistic regression analysis in AHT, including characteristics at baseline and at follow-up, baseline SIS (OR = 2.8, 95% CI = 0.94 to 8.38) and symptoms of asthma in general during follow-up (OR = 2.2, 95% CI = 0.94 to 5.38) were the main determinants for quitting, though they were of borderline significance. We conclude that health-related self-selection out of an apprenticeship with exposure to HMW agents is likely to occur and to cause an attrition bias.

Airway hyperresponsiveness and symptoms of asthma in a six-year follow-up study of childhood asthma

BACKGROUND AND AIM

In an inception cohort study of 457 asthmatic children diagnosed at the age of 3 to 4 years, airway hyperresponsiveness (AHR) was assessed 6 years after first diagnosis in a subgroup of 84 children. Our objective was to associate the level of AHR with the symptomatic asthma status at follow-up.

METHODS

Information on respiratory symptoms and medication use for the previous 6 years was obtained. Children with reported wheezing episodes during the previous year (n = 169) or for > or = 2 years at any time during the follow-up period (n = 85) were eligible for the challenge test.

RESULTS

Among the 254 eligible children, 166 were randomly selected. The parents of 88 of them consented to have their child participate. At the time of assessment of AHR, 19 children (22%) were asymptomatic and 24 others (29%) had symptoms but did not use any medication. Forty-one children (49%) were symptomatic and required medication, including antiinflammatory preparations in 26 instances (31%). All but two children had significant AHR. There was no significant association between the level of AHR and graded symptomatic and medication score. Twenty-four of the 70 children (34%) with greatly enhanced AHR used no medication.

CONCLUSIONS

This study shows that (1) almost all children first diagnosed with asthma 6 years ago and with persisting but not necessarily current symptoms of asthma have increased AHR, which satisfies a proposed epidemiologic definition of asthma; (2) AHR was present in 95% of the 20 currently asymptomatic children; and (3) one third of children with greatly enhanced AHR did not use any treatment.

Protected specimen brush or bronchoalveolar lavage to diagnose bacterial nosocomial pneumonia in ventilated adults: a meta-analysis

OBJECTIVE

We conducted a meta-analysis by using summary receiver operating characteristic curves to compare the diagnostic value for bacterial nosocomial pneumonia of the following: a) quantitative culture (colony-forming units per milliliter or CFU/mL) of respiratory secretions collected with a bronchoscopic protected specimen brush (PSB); b) quantitative culture of a bronchoscopic bronchoalveolar lavage (BAL); and c) the percentage of infected cells (IC) in BAL.

DATA SOURCES

All studies published in the English or the French language, through January 1, 1995, on the evaluation of PSB or BAL for the diagnosis of pneumonia were considered for analysis. The relevant literature was identified through computer and reference searching and by experts in the field.

STUDY SELECTION

A study was included if at least two of three independent readers regarded its purpose as the evaluation of CFU-PSB, CFU-BAL, or IC-BAL for the diagnosis in human beings of bacterial nosocomial pneumonia in ventilated adults and if the study was prospective and published in a peer-reviewed journal.

DATA EXTRACTION

Three readers reviewed all published articles and decided whether to include each study; consensus was defined as agreement by at least two readers. The authors of each original article included in the meta-analysis were asked to complete a questionnaire in which they were asked to check and to correct the data extracted by one of the independent readers.

DATA SYNTHESIS

Summary receiver operating characteristic curves were used to compare the efficacy of three diagnostic tests. Eighteen studies on CFU-PSB (795 patients) were included, as well as 11 studies on CFU-BAL (435 patients) and 11 on IC-BAL (766 patients). The accuracy of these tests was not different. However, it seems that administration of previous antibiotics markedly decreased accuracy of CFU-PSB (p = .0002) but not the accuracy of CFU-BAL and that of IC-BAL.

CONCLUSION

Both PSB and BAL are reliable to diagnose bacterial nosocomial pneumonia. Because CFU-BAL and IC-BAL seemed more resistant to the effects of antibiotics, we recommend BAL rather than PSB if the patient is already receiving antibiotics.

Prevalence of congenital anomalies at birth among offspring of women at risk for a genetic disorder and with a normal second-trimester ultrasound

The goal of this study was to determine the prevalence and the nature of congenital anomalies found at birth in offspring of women who had a normal second-trimester ultrasound and/or amniocentesis. Two groups of women were studied in our prenatal diagnosis clinic between 1991-1997. Group 1 consisted of pregnant women who had an amniocentesis for advanced maternal age (AMA), or for familial chromosomal or monogenic disorders. Group 2 consisted of pregnant women attending the prenatal diagnosis clinic and who had no indication for amniocentesis. Those with an abnormal ultrasound and/or amniocentesis were excluded. At the time of delivery, a questionnaire was sent pertaining to perinatal complications and the anomalies detected during the neonatal period. From a total of 15, 370 questionnaires sent from 1991-1997, 10,823 (group 1, n = 8,877; group 2, n = 1,946) were returned (overall response rate, 70.4%). Mean maternal age was 36 years in group 1 and 29 years in group 2. The prevalence of perinatal complications was similar in the two groups. In each group, the prevalence of all unforeseen anomalies was 2.9%. In group 1, the distribution of those anomalies was: major anomalies, 67.7%; minor anomalies, 23.9%; and multiple congenital anomalies (MCA), 8.3%. In group 2, the distribution was: major anomalies, 70.7%; minor anomalies, 24.1%; and MCA, 5.2%. In patients at risk for a genetic disease and consulting in a prenatal diagnosis clinic, the prevalence of all anomalies diagnosed at birth was 2.9%, even if the second-trimester ultrasound and amniocentesis results were normal. Therefore, it is important to inform those couples of this remaining risk.

Longitudinal assessment of airway caliber and responsiveness in workers exposed to chlorine

This longitudinal study (1992-1994) was performed to determine the relation between accidental chlorine exposure and changes in lung function and airway responsiveness in 239 workers in a metal production plant. These workers had taken part in a cross-sectional survey in 1992. In both the initial and the follow-up surveys, history of exposure to chlorine ("puffs"), accidental chlorine inhalation reported to the first-aid unit (gassing incidents), and of chronic symptoms were documented; spirometry and methacholine challenge tests were performed. At follow-up, 211 workers (88.3%) were seen. In workers with 20 pack-years or more of cigarette smoking, the fall in FEV(1) was associated with having had a gassing incident during the follow-up period; the fall in FEV(1)/FVC (%) was predicted by the number of puffs causing mild symptoms between the two assessments. An increase in airway responsiveness (PC(20) decrease > 1.5-fold) was present in 19 workers; it was associated with accidents reported to the first-aid unit during the previous 2 yr (OR: 5.9, 95% CI: 1.1 to 32.3). These findings suggest: (1) an effect on airway function related to the estimated number of puffs with mild symptoms and gassing incidents, mostly among smokers; (2) a detectable increase in airway responsiveness associated with gassing incidents.

Maternal smoking and childhood asthma

The role of maternal smoking as a causal factor for the incidence of childhood asthma is still not clearly established. It was investigated among 3- and 4-year-old-child incident cases confirmed by a 6-year follow-up (n = 294) and cases who no longer had symptoms after diagnosis (n = 110). The study took place in Montréal, Canada, between 1988 and 1997. Persistent and transient cases were compared with their respective controls from the original case-control study of incidence. The odds ratio for heavy maternal smoking adjusted for known risk factors for asthma was 3.84 (95% confidence interval: 1.68, 8.76) among persistent cases and close to one among transient cases.

Risk of childhood leukemia associated with exposure to pesticides and with gene polymorphisms

We conducted a population-based case-control study of childhood acute lymphoblastic leukemia (ALL) to evaluate the risk posed by reported exposure to pesticides used in and around the home. We compared 491 cases 0-9 years of age to as many controls. We also conducted a case-only study on a subsample of 123 cases to evaluate gene-environment interaction between child genotype and maternal exposure during pregnancy as well as child exposure after birth. We used the polymerase chain reaction (PCR) approach to analyze polymorphisms in CYP1A1, CYP2D6, GSTT1, and GSTM1 genes, which encode enzymes involved in carcinogen metabolism. Indoor use of some insecticides by the owners and pesticide use in the garden and on interior plants, in particular frequent prenatal use, was associated with increased risks up to severalfold in magnitude. Interaction odds ratios were increased among carriers of the CYP1A1m1 and CYP1a1m2 mutations when mother during pregnancy or the child had been exposed to certain indoor insecticides. No such effects were observed in the presence of other tested polymorphisms.

Case-control study of lung cancer among sugar cane farmers in India

OBJECTIVES

To investigate the risk of lung cancer among sugar cane farmers and sugar mill workers.

METHODS

A case-control study was conducted based in six hospitals in the predominantly sugar cane farming districts of the province of Maharashtra in India. Newly diagnosed, histologically confirmed cases were identified from these hospitals between May 1996 and April 1998. Other cancers were chosen as controls and matched to cases by age, sex, district of residence, and timing of diagnosis.

RESULTS

Adjusting for confounders, an increased risk of lung cancer was found for workers ever employed on a sugar cane farm (odds ratio (OR) 1.92, 95% confidence interval (95% CI) 1.08 to 3.40). Increased risks were found for work involving preparation of the farm (OR 1.81, 95% CI 0.99 to 3.27) and burning of the farm after harvesting (OR 1.82, 95% CI 0.99 to 3.34). Non-significant increases in risks were found for harvesting the crop (OR 1.41, 95% CI 0.70 to 2.90) and processing the cane in the mills (OR 1.70, 95% CI 0.20 to 12.60).

CONCLUSIONS

Exposure to fibres of biogenic amorphous silica (BAS) formed from silica absorbed from the soil and deposited in the leaves of the sugar cane crop or crystalline silica formed as a result of conversion of BAS to cristobalite at high temperatures may account for the increased risks of lung cancer among sugar cane farmers.

Risk factors for acquisition of hepatitis C virus infection in blood donors: results of a case-control study

BACKGROUND & AIMS

Few studies have explored risk factors predicting hepatitis C virus (HCV) infection in blood donors; their results are contradictory. The aim of this study was to evaluate the association between HCV infection and various risk factors in Canadian volunteer blood donors.

METHODS

Four transfusion centers were involved in this case-control study. A total of 267 confirmed anti-HCV-positive blood donors were interviewed along with 1068 seronegative blood donors matched for sex, age, donation site, and date. Information was collected using a structured telephone interview. The main outcome measures were odds ratios (ORs) and 95% confidence intervals (CIs) for various risk factors from univariate and multivariate analyses using conditional logistic regression.

RESULTS

By univariate analysis, 23 variables were associated with anti-HCV positivity. In the final multivariate analysis, only 5 factors remained independently predictive of HCV infection: previous intravenous drug use (OR, 127.5; 95% CI, 26.0-625.0), having lived in a prison or juvenile detention center (56.1; 11.4-275.7), previous blood transfusion (10.5; 4.7-23.2), sexual contact with an intravenous drug user (6.9; 3.1-15.2), and tattooing (5.7; 2.5-13).

CONCLUSIONS

Most blood donors acquire infection by percutaneous exposure to contaminated blood. A role for sexual transmission is suggested by this study.

Changes in airway function and bronchial responsiveness after acute occupational exposure to chlorine leading to treatment in a first aid unit

OBJECTIVES

To describe the baseline characteristics and the time course of changes in lung function in workers accidentally inhaling high concentrations of chlorine in a prospective study.

METHODS

Baseline spirometry and methacholine challenge test were performed in a cohort of 278 workers at risk of accidental inhalation of chlorine. Workers in whom accidental inhalation led to intervention in a first aid unit were reassessed five to 25 days after the accident and serially thereafter when there where notable changes.

RESULTS

During a four year follow up period, 13 workers were seen at the first aid unit after a symptomatic accidental inhalation. Three of them experienced notable functional changes: one worker experienced a 10% fall in forced expiratory volume in one second (FEV1), and the other two had a notable fall in the concentration of methacholine that caused a 20% fall in FEV1 (PC20). Two workers were smokers and one had a personal history of atopy. Baseline assessment was within the normal range in these three workers. Recovery was complete three months after the accidental inhalation.

CONCLUSION

Transient but notable decreases in airway function or increases in bronchial responsiveness can occur after an accidental inhalation of high concentrations of chlorine in workers at risk.

Use of physician services among family caregivers of elderly persons with dementia

It is well known that there is an excess of physical and psychological health problems among family caregivers of elderly persons with Alzheimer's disease and other dementias. The objective of this study was to determine whether the higher level of morbidity translates into a higher level of medical care utilization. Data from a previously completed longitudinal study of caregivers for elderly persons with dementia were merged with data on physician visits obtained from the computerized records of the Quebec Health Insurance Board. Utilization of physician care (adjusted for age, sex, number of chronic diseases, and depression) was no higher for family caregivers of elderly patients with Alzheimer's disease and other dementias than for comparable family members of older persons without dementia. The annual cost of physician care was almost identical among caregivers and noncaregivers. However, the pattern of utilization for the two groups was somewhat different: there was a significantly higher frequency of physician utilization among caregivers for services billed by psychiatrists and internal medicine specialists. In multivariate analysis, physician utilization was significantly associated with having more than one chronic condition and with increased age. Future studies should focus on determining whether caregivers neglect their own health care needs as a result of the exigencies of the caregiving role.

Specific IgE-dependent sensitization, atopy, and bronchial hyperresponsiveness in apprentices starting exposure to protein-derived agents

Atopy, specific IgE sensitization, and bronchial hyperresponsiveness (BHR) were examined in a cohort of 769 apprentices starting career programs in animal health or veterinary medicine (Group 1), pastry making (Group 2), and dental hygiene (Group 3). The hypothesis were that: (1) a proportion of subjects can be "sensitized" although no significant specific occupational exposure has occurred; and (2) there is a relationship between baseline specific sensitization to work-related antigens and host characteristics. Skin tests were administered using 11 common inhalants and specific allergens, including six laboratory animal extracts, three cereal antigens, alpha-amylase, and latex. Methacholine challenge tests were performed. The prevalence of atopy was 54.4% in Group 1, 58.1% in Group 2, and 52.5% in Group 3. Skin reactivity to work-specific proteins was as follows: laboratory animal proteins, 13.8% in Group 1, 14.0% in Group 2, and 15.6% in Group 3. No subject was sensitized to alpha-amylase, whereas 1.2% in Group 1, 5% in Group 2, and 4.1% in Group 3 were sensitized to flour. Five subjects reacted to latex. BHR (PC20 < or = 8 mg/ml) was present in 17.6%, 21.2%, and 14.8% of subjects in Groups 1, 2, and 3, respectively. Specific sensitization was associated with positive skin reactions to common allergens, work-related symptoms, and BHR. These results suggest that students starting career programs with exposure to high-molecular-weight allergens have a low but substantial frequency of specific sensitization to work-related allergens that is related to atopy and BHR.