Mireille Chiron

Traffic related air pollution and incidence of childhood asthma: results of the Vesta case-control study

Study objective: The Vesta project aims to assess the role of traffic related air pollution in the occurrence of childhood asthma. Design and setting: Case-control study conducted in five French metropolitan areas between 1998 and 2000. A set of 217 pairs of matched 4 to 14 years old cases and controls were investigated. An index of lifelong exposure to traffic exhausts was constructed, using retrospective information on traffic density close to all home and school addresses since birth; this index was also calculated for the 0–3 years age period to investigate the effect of early exposures. Main results: Adjusted on environmental tobacco smoke, personal and parental allergy, and several confounders, lifelong exposure was not associated with asthma. In contrast, associations before age of 3 were significant: odds ratios for tertiles 2 and 3 of the exposure index, relative to tertile 1, exhibited a positive trend (1.48 (95%CI = 0.7 to 3.0) and 2.28 (1.1 to 4.6)), with greater odds ratios among subjects with positive skin prick tests. Conclusions: These results suggest that traffic related pollutants might have contributed to the asthma epidemic that has taken place during the past decades among children.

Bicycle helmet wearing and the risk of head, face, and neck injury: a French case–control study based on a road trauma registry

Background Previous case–control studies on bicycle helmet efficacy are mostly Anglo-Saxon, and based on data from the early 1990s when hard-shell helmets were common. Methods In France, the Rhône county (1.6 million inhabitants) is covered by a road trauma registry that includes emergency department visits, hospital admissions, and fatalities. Over the 1998–2008 period, 13 797 cyclist casualties were identified. The injuries sustained were coded using the Abbreviated Injury Scale (AIS) for injuries to the head (AIS1+ and AIS3+), face (AIS1+), or neck (AIS1+). The study uses a case–control design where the control group includes cyclists injured below the neck—that is, not injured in the region associated with the helmet. We first adjusted for age, gender, and type of crash, as in a previously published Cochrane review. Then we adjusted for injury severity based on non-head, face, or neck injury, and when relevant, for crash location: type of road, urban/rural area. Results The fully adjusted ORs of helmeted versus unhelmeted cyclists are: for AIS1+ head injuries, 0.69 (95% CI 0.59 to 0.81); for AIS3+ head injuries sustained in urban areas, 0.34 (95% CI 0.15 to 0.65), those sustained in rural areas, 0.07 (95% CI 0.02 to 0.23); for AIS1+ facial injuries, 0.72 (95% CI 0.62 to 0.83); and for AIS1+ neck injuries, 1.18 (95% CI 0.94 to 1.47). Conclusion This study confirms the protective effect for head and facial injuries, even though soft-shell helmets have now become more common. The reduction of risk is greater for serious head injuries. The study is inconclusive about the risk for neck injuries.

EMOTIONAL STRESS AND TRAFFIC ACCIDENTS. THE IMPACT OF SEPARATION AND DIVORCE

Background: Personal responses to stressful life events are suspected of increasing the risk of serious traffic accidents. Methods: We analyzed data from a French cohort study (the GAZEL cohort), including a retrospective driving behavior questionnaire, from 13,915 participants (10,542 men age 52–62 years and 3373 women age 47–62 years in 2001). Follow-up data covered 1993–2000. Hazard ratios for serious accidents (n = 713) were computed by Coxs proportional hazard regression with time-dependent covariates. Separate analyses were also performed to consider only at-fault accidents. Results: Marital separation or divorce was associated with an increased risk of a serious accident (all serious accidents: hazard ratio 2.9, 95% confidence interval = 1.7–5.0; at-fault accidents: 4.4, 2.3–8.3). The impact of separation and divorce did not differ according to alcohol consumption levels. Other life events associated with increased risk of serious accident were a child leaving home (all accidents: 1.2, 0.97–1.6; at-fault accidents: 1.5, 1.1–2.1), an important purchase (all accidents: 1.4, 1.1–1.7; at-fault accidents: 1.6, 1.2–2.1), and hospitalization of the partner (all accidents: 1.4, 1.1–2.0). Conclusion: This study suggests that recent separation and divorce are associated with an increase in serious traffic accidents.

The injury epidemiology of cyclists based on a road trauma registry.

BackgroundBicycle use has increased in some of Frances major cities, mainly as a means of transport. Bicycle crashes need to be studied, preferably by type of cycling. Here we conduct a descriptive analysis.MethodA road trauma registry has been in use in France since 1996, in a large county around Lyon (the Rhône, population 1.6 million). It covers outpatients, inpatients and fatalities. All injuries are coded using the Abbreviated Injury Scale (AIS). Proxies were used to identify three types of cycling: learning = children (0-10 years old); sports cycling = teenagers and adults injured outside towns; cycling as means of transport = teenagers and adults injured in towns. The study is based on 13,684 cyclist casualties (1996-2008).ResultsThe percentage of cyclists injured in a collision with a motor vehicle was 8% among children, 17% among teenagers and adults injured outside towns, and 31% among those injured in towns. The percentage of serious casualties (MAIS 3+) was 4.5% among children, 10.9% among adults injured outside towns and 7.2% among those injured in towns. Collisions with motor-vehicles lead to more internal injuries than bicycle-only crashes.ConclusionThe description indicates that cyclist type is associated with different crash and injury patterns. In particular, cyclists injured in towns (where cycling is increasing) are generally less severely injured than those injured outside towns for both types of crash (bicycle-only crashes and collisions with a motor vehicle). This is probably due to lower speeds in towns, for both cyclists and motor vehicles.

The Fatal Injuries of Car Drivers

We often refer to road fatalities without knowing exactly what injuries are responsible for them. Based on the Rhône Road Trauma Registry this paper sets out to describe the topography, nature and frequency of the fatal injuries sustained by car drivers. Mean annual mortality at the wheel of a car, computed by dividing the total number of drivers killed (n=383) by the population of the Rhône Département (1.6 million) during the period 1996-2004 was 5.41 males per 100,000 and 1.41 females per 100,000, with 78% of the casualties residing in the Département. A reduction has been observed since 2003. Three-quarters of the casualties died at the scene of the crash. The results confirm the effectiveness of seat belts. The observed lethality was 0.43% for unbelted drivers and 2.7% for belted drivers (RR=0.16 [0.12; 0.21]). The injuries were analyzed for the 287 killed drivers whose deaths could be explained by the described injuries (at least one AIS 4+ injury). Of these, 41% had an ISS of 75 (at least one AIS 6 injury), 21% had an ISS of between 40 and 74, 33% an ISS of between 25 and 40, and 6% an ISS of between 16 and 24. In the case of all the AIS 4+ injuries, the three most frequent locations for injuries were the thorax only (30% of casualties), the head only (23%) and a combination of the two (18%). Abdominal injuries occurred in only 10% of casualties and spinal injuries in 9% of casualties. In the thorax, the most common injury was flail chest with haemothorax or pneumothorax. In the case of the head, the most frequent injuries were to the brain (haemorrhage, haematoma and axonal injuries). Complex fractures of the base of the skull were the second most common craniocephalic injuries. In spite of the use of restraint devices, the thorax and head are still the priority vital areas for protection in the case of car drivers. For one in four of the fatalities, death cannot be explained by any of the injuries we know about. As road traffic accidents are considered to be a cause of death in their own right, autopsies are rarely performed in France on such fatalities. This means we do not know about any injuries that cannot be detected by an external examination of the cadaver.

Work-related road accidents in France

A descriptive analysis of all victims of road accidents recorded by the police in 1997 was carried out, distinguishing accidents occurring in the course of work, while commuting and for private reasons. The analysis concerned 105,816 drivers from 14 to 64 years of age; among these, 9.9% were injured during the course of work and 18.6% while commuting. The gender-ratio was maximal for accidents during the course of work (SR = 5.5) and minimal while commuting (2.1). Accidents in the course of work were generally less serious than the two other types aforementioned. Compared with the incidence rates for labourers, those of self-employed trades and services (SETS) and those of employees and executives were higher for accidents incurred during the course of work and lower for those incurred during commuting. Professional drivers had the highest risk during the course of work. Accidents while working were most serious for SETS and professional drivers. Although it was impossible to take into account the mileage travelled, this study points out the real share of work-related road accidents and shows the need to develop and adapt prevention to the groups at risk that we have identified.

Attitudes associated with behavioral predictors of serious road traffic crashes: results from the GAZEL cohort

Objectives: To test the hypothesis that behavioral predictors of serious road traffic crashes (RTC) are correlated with unfavorable attitudes towards traffic safety. Design: Prospective and cross-sectional cohort study. Setting: France Participants: 13 447 of the 19 894 living members of the GAZEL cohort, workers and recent retirees of a French national utility company followed up since 1989. Main outcomes measures: Driving behavior and attitudes towards traffic safety in 2001 by questionnaire. Serious RTCs were recorded over the subsequent 3 years using the cohort annual questionnaire. Behavioral predictors of serious RTCs were assessed using generalized linear Poisson regression models with time-dependent covariates. Factor scores extracted from the first four attitudinal factors of principal component analysis were saved and then regressed on behavioral predictors as independent variables. Results: After controlling for potential confounders, the best predictors of serious RTCs were: “exceeding speed limits on rural roads”, “risky use of cellular phone”, and “sleepy driving”. The adjusted rate ratio ranged from 1.47 to 2.16. Predictors of contravention of the highway code (the first two predictors) were found to be strongly associated with negative attitudes towards “enforcement” and “speed limitations” with an adjusted odds ratio ranging from 1.31 to 2.02. Conclusion: Our study supports the view that individuals with a high propensity for driving behaviors associated with an increased risk of RTCs were more likely to have negative attitudes towards traffic safety. Changing drivers’ negative or distorted opinions of traffic “enforcement” as well as “speed limitations” and “alcohol prohibition on roads” could improve their compliance with road traffic rules.

Maternal residence near municipal waste incinerators and the risk of urinary tract birth defects

Objectives Waste incineration releases a mixture of chemicals with high embryotoxic potential, including heavy metals and dioxins/furans, into the atmosphere. In a previous ecological study we found an association between the risk of urinary tract birth defects and residence in the vicinity of municipal solid waste incinerators (MSWIs). The objective of the present study was to specifically test this association. Methods A population-based case–control study compared 304 infants with urinary tract birth defects diagnosed in the Rhône-Alpes region (2001–2003) with a random sample of 226 population controls frequency-matched for infant sex and year and district of birth. Exposure to dioxins in early pregnancy at the place of residence, used as a tracer of the mixture released by 21 active waste incinerators, was predicted with second-generation Gaussian modelling (ADMS3 software). Other industrial emissions of dioxins, population density and neighbourhood deprivation were also assessed. Individual risk factors including consumption of local food were obtained by interviews with 62% of the case and all control families. Results Risk was increased for mothers exposed to dioxins above the median at the beginning of pregnancy (OR 2.95, 95% CI 1.47 to 5.92 for dioxin deposits). When only interviewed cases were considered, risk estimates decreased mainly because the non-interviewed cases were more likely to live in exposed residential environments (OR 2.05, 95% CI 0.92 to 4.57). The results suggest that consumption of local food modifies this risk. Conclusions This study confirms our previous observation of a link between the risk of urinary tract birth defects and exposure to MSWI emissions in early pregnancy and illustrates the effect of participation bias on risk estimates of environmental health impacts.

Five epidemiological studies on transport and asthma: objectives, design and descriptive results.

A case–control study was conducted in five French metropolitan areas in order to assess the role of traffic-related air pollution in the occurrence of childhood asthma. This paper presents the study design and describes the distribution of key exposure variables. A set of 217 pairs of matched 4- to 14-year-old cases and controls were investigated (matching criteria: city, age, and gender). Current and past environmental smoke exposures, indoor allergens or air pollution sources, and personal and family atopy were assessed by standard questionnaires. When possible, direct measurements were done to check the validity of this information, on current data: skin prick tests, urine cotinine, house dust mites densities, personal exposures to, and home indoor concentrations of NOx and PM2.5. Cumulative exposure to traffic-related pollutants was estimated through two indices: “traffic density” refers to a time-weighted average of the traffic density-to-road distance ratio for all home and school addresses of each childs life; “air pollution” index combines lifelong time–activity patterns and ambient air concentration estimates of NOx, using an air dispersion model of traffic exhausts. Average current PM2.5 personal exposure is 23.8 μg/m3 (SD=17.4), and average indoor concentrations=22.5 μg/m3 (18.2); corresponding values for NO2 are 31.4 (13.9) and 36.1 (21.4) μg/m3. Average lifelong calculated exposures to traffic-related NOx emissions are 62.6 μg/m3 (43.1). The five cities show important contrasts of exposure to traffic pollutants. These data will allow comparison of lifelong exposures to indicators of traffic exhausts between cases and controls, including during early ages, while controlling for a host of known enhancers or precipitators of airway chronic inflammation and for possible confounders.

Management of severely injured children in road accidents in France: Impact of the acute care organization on the outcome

Objective: To examine the impact of acute care management on outcome in children severely injured in road accidents. Design and Setting: Prospective follow-up study conducted in 12 French pediatric intensive care units over a 24-month period. Patients: Excluding those in refractory shock or in brain death at admission, a total of 125 children aged <17 years admitted to the pediatric intensive care unit with severe trauma (Injury Severity Score ≥16) were included. Results: Intracranial pressure (ICP) monitoring and admission into a trauma resuscitation room (TRR) were used as proxy markers for the center management aggressiveness. Centers which admitted to TRR and monitored ICP when indicated in >75% of cases were called aggressive centers. Children with an ICP monitoring indication admitted to a TRR and monitored, as well as those without an indication treated in a TRR, were judged appropriately managed. A poor outcome at pediatric intensive care unit discharge was defined as a difference between the baseline and discharge pediatric overall performance category above 3, or a hospital death. Children with traumatic brain injury appropriately managed in a less-aggressive center were more likely to have a poor outcome than those appropriately managed in an aggressive center (odds ratio 7.56, 95% confidence interval 1.5–38.4), after adjustment for severity, age, and type of road user. Conclusions: The management in a more aggressive center for children admitted to TRR and monitored for ICP, when indicated, is associated with a better outcome. This could be explained by a more extensive experience in trauma management.