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Biomedical subjects

Pascal Wild

Publications and source records attributed to Pascal Wild.

11 recordsLinked to original sources
PubMed2006

Ototoxicity in rats exposed to ethylbenzene and to two technical xylene vapours for 13 weeks.

Male Sprague-Dawley rats were exposed to ethylbenzene (200, 400, 600 and 800 ppm) and to two mixed xylenes (250, 500, 1,000 and 2,000 ppm total compounds) by inhalation, 6 h/day, 6 days/week for 13 weeks and sacrificed for morphological investigation 8 weeks after the end of exposure. Brainstem auditory-evoked responses were used to determine auditory thresholds at different frequencies. Ethylbenzene produced moderate to severe ototoxicity in rats exposed to the four concentrations studied. Increased thresholds were observed at 2, 4, 8 and 16 kHz in rats exposed to 400, 600 and 800 ppm ethylbenzene. Moderate to severe losses of outer hair cells of the organ of Corti occurred in animals exposed to the four concentrations studied. Exposure to both mixed xylenes produced ototoxicity characterized by increased auditory thresholds and losses of outer hair cells. Ototoxicity potentiation caused by ethylbenzene was observed. Depending on the mixed xylene studied and the area of the concentration-response curves taken into account, the concentrations of ethylbenzene in mixed xylenes necessary to cause a given ototoxicity were 1.7-2.8 times less than those of pure ethylbenzene. Given the high ototoxicity of ethylbenzene, the safety margin of less or equal to two (LOAEL/TWA) might be too small to protect workers from the potential risk of ototoxicity. Moreover, the enhanced ototoxicity of ethylbenzene and para-xylene observed in mixed xylenes should encourage the production of mixed xylenes with the lowest possible concentrations of ethylbenzene and para-xylene.

Air Pollutants, Occupational↗
PubMed2006

Comparison of potential adjustment variables representing primary intellectual level in epidemiological studies on neurotoxicity.

BACKGROUND: Primary intellectual abilities (PIA) are a confounder in epidemiological studies on neurotoxicity. A good measure of this confounder should be independent of age as PIA is an intrinsic ability. Furthermore, as PIA is related to health endpoints, any measure of PIA should reveal this association. This study is aimed at comparing vocabulary test, diploma and age at end of schooling properties as measures of PIA in a non-exposed population of workers. METHODS: The design was a cross-sectional study of 413 non-exposed workers (203 women and 210 men) selected from a health check-up center. The effect of age on the vocabulary score was assessed using an analysis of covariance adjusted for diploma. Relationships between neuropsychological performances and vocabulary score, diploma and end of schooling age were, respectively, assessed using multiple linear regressions adjusted for age and gender. RESULTS: Vocabulary score increased significantly with age, both for men and women. The increase was 0.14 word per year for women, and 0.18 word per year for men. The explained variance of the models evaluating the relationships between age at end of schooling, diploma, vocabulary test, and neuropsychological performances was quite similar for the three measures of PIA. CONCLUSIONS: Vocabulary score was found to be age-related, even after adjustment for diploma. No difference was found between these three variables in terms of their relationship to neuropsychological endpoints. Moreover, the literature shows that vocabulary test performances are influenced by exposure to neurotoxic agents. These results suggest that vocabulary score could be of interest for participants of similar ages and similar diplomas. Otherwise, the other two variables would be better PIA measures in neurotoxicology studies.

Adult↗
PubMed2006

Cancer mortality in workers exposed to organochlorine compounds in the pulp and paper industry: an international collaborative study.

The objective of this study was to evaluate cancer mortality in pulp and paper industry workers exposed to chlorinated organic compounds. We assembled a multinational cohort of workers employed between 1920 and 1996 in 11 countries. Exposure to both volatile and nonvolatile organochlorine compounds was estimated at the department level using an exposure matrix. We conducted a standardized mortality ratio (SMR) analysis based on age and calendar-period-specific national mortality rates and a Poisson regression analysis. The study population consisted of 60,468 workers. Workers exposed to volatile organochlorines experienced a deficit of all-cause [SMR = 0.91; 95% confidence interval (CI), 0.89-0.93] and all-cancer (SMR = 0.93; 95% CI, 0.89-0.97) mortality, with no evidence of increased risks for any cancer of a priori interest. There was a weak, but statistically significant, trend of increasing risk of all-cancer mortality with increasing weighted cumulative exposure. A similar deficit in all-cause (SMR = 0.94; 95% CI, 0.91-0.96) and all-cancer (SMR = 0.94; 95% CI, 0.89-1.00) mortality was observed in those exposed to nonvolatile organochlorines. No excess risk was observed in cancers of a priori interest, although mortality from Hodgkin disease was elevated (SMR = 1.76; 95% CI, 1.02-2.82) . In this study we found little evidence that exposure to organochlorines at the levels experienced in the pulp and paper industry is associated with an increased risk of cancer, apart from a weak but significant association between all-cancer mortality and weighted cumulative volatile organochlorine exposure.

Humans↗
PubMed2006

Update of a meta-analysis on lung cancer and welding.

OBJECTIVES: This study is an update, over the period 1954-2004, of a previous meta-analysis completed in 1994. It was aimed at assessing lung cancer risk among welders, while addressing heterogeneity, publication bias, and confounding issues. METHODS: Combined relative risks (CRR) and their variances were calculated using fixed and random effects models. Heterogeneity was tested using the Q statistic. The publication bias was estimated using funnel plots, and Egger's regression and partially controlled by excluding studies with positive reporting bias. RESULTS: The literature provided 60 studies eligible for the meta-analysis. No heterogeneity was observed. The fixed effect CRR for all of the welders and all of the studies was 1.26 (95% CI 1.20-1.32) after partial control of publication bias. No difference was observed according to welding activities. Smoking did not appear to be a marked confounder in the relationship between lung cancer and welding, but the effect of asbestos could not be assessed. CONCLUSIONS: The meta-analysis showed a 26% excess of lung cancer for welders without any difference according to welding activities.

Americas↗
PubMed2005

Shiftwork experience, age and cognitive performance.

Changes of alertness and cognitive efficiency has been suggested in people whose circadian rhythms are disrupted, e.g. night or shift-workers. Data from field and laboratory studies have demonstrated short-term cognitive disturbances related to circadian rhythm disruption. By contrast, little is known about the long-term consequences of chronic sleep deprivation, as can be observed with shift-work, on cognitive abilities. The present paper is aimed at evaluating, on a large cross-sectional sample of workers, the long-term influence of shift-work on verbal memory and speed performances. Participants were 3,237 workers aged 32, 42, 52, and 62 years of various occupational statuses included in the VISAT (Aging, Health and Work) cohort. Data collected by questionnaires included items on working hours and shift-work and sleep disorders. Cognitive abilities were assessed using neuropsychological tests. Current male shift-workers had lower cognitive performance than never exposed workers. In the same population, memory performance tended to decrease with increasing shift-work duration. Among former shift-workers, the cognitive performance of the participant having stopped shiftwork more than 4 years ago seemed to be increased, suggesting a possible reversibility of effects. In conclusion, this study demonstrated that cognitive functioning tends to be impaired by a long-term exposure to SW. As found by other authors, neuropsychological performance tends to decrease with the increases in the duration of exposure to SW.

Adult↗
PubMed2005

Cancer mortality among municipal pest-control workers.

OBJECTIVES: This epidemiological study was carried out in order to investigate the hypothesis of a relationship between cancer occurrence and occupational exposure in a population of municipal pest-control workers exposed to a wide range of pesticides and other chemicals. METHODS: The study was designed as a mortality historical cohort study. The cohort comprised all subjects ever employed in a municipal pest-control service between 1979 and 1994. The follow-up period lasted from 1979 to 2000. The mortality rates of pest-control workers were compared with those of a regional population. A job exposure matrix was developed, which took into account four types of chemicals: formaldehyde, ethylene oxide, insecticides and rodenticides. RESULTS: None of the 181 subjects of the cohort, leading to 3,107 person-years, was lost to follow-up. Thirty-nine of them died, and all the causes of deaths were ascertained. The standardized mortality ratios (SMRs) for all causes of deaths and for all cancer causes were significantly greater than unity: 1.61 (1.14-2.20) and 2.24 (1.39-3.43), respectively. Non-significant excesses were observed for most cancer sites, except for lung cancer, which had a low SMR. We obtained significant excesses for cancer in workers with more than 20 years of employment [SMR = 2.42 (1.43-3.82)]. Cancer mortality tended to increase insignificantly with formaldehyde and rodenticides exposures, whereas no clear patterns were observed for ethylene oxide and insecticides. However, significant excesses were observed for the highest exposure levels of formaldehyde, insecticides and rodenticides. CONCLUSIONS: This study showed a statistically significant excess of cancer mortality in a population of municipal pest-control workers exposed to a wide variety of chemicals. These cancer sites might be related to occupational activities, since they tended to be more frequently observed when duration of employment increased.

Adolescent↗
PubMed2004

Exposure to job-stress factors in a national survey in France.

OBJECTIVES: Job stress is a growing epidemiologic field in France. The aim of this study was to evaluate the levels of occupational psychosocial risk factors to which the French working population is exposed. It also focused on developing a job-exposure matrix. METHODS: This study used existing French national data on work conditions collected by the French Ministry of Labor in 1991, in which 20 929 workers were interviewed by questionnaire. The items of the questionnaire were retained that represented potential stressors. A principal component analysis was performed to summarize the data in terms of job-stress factors. Four independent variables (gender, age, occupation, and activity) were available, as well as scores for exposure to psychosocial risk factors. The CART (classification and regression tree) segmentation method was used to construct the job-exposure matrix. RESULTS: Fourteen psychosocial factors were identified and interpreted on the basis of the results of the principal component analysis and deepened by experts' judgment. To take into account the well-known difference of distribution in occupations between men and women, a gender-specific matrix was developed. CONCLUSIONS: This study is the first attempt to develop a job-exposure matrix in the area of job-stress factors in France. Thus the results have allowed the assessment of exposure to 14 psychosocial factors for all of the 455 categories of the French occupational classification for men and women separately.

Adult↗
PubMed2003

Evaluation of the French version of EUROQUEST: a questionnaire for neurotoxic symptoms.

BACKGROUND: EUROQUEST was designed to explore various neuropsychiatric symptoms caused by neurotoxic agents in occupational epidemiological studies. This paper was aimed at assessing (i) the internal consistency of the French version of EUROQUEST, (ii) its sensitivity to age, educational level and exposure, (iii) and its convergent validity by examining relationships between declared symptoms and results from psychometric tests on the same mental functions. DESIGN: Data from four cross-sectional studies were selected: 180 workers exposed to toluene, mixed solvents or anaesthetic gas, and 588 non-exposed ones. The internal consistency of the questionnaire was assessed by computing Cronbach's alphas. Sensitivity to age, educational level and exposure were assessed with multiple linear regression models. Relationships between EUROQUEST scores and correspondent neuropsychological tests were assessed with Pearson's correlation coefficients. The relationships between EUROQUEST domain specific scores, age and educational level were evaluated for men and women from the Reference group. Most of the analyses were performed in men and women separately. RESULTS: The results of the Cronbach's alphas computed for each EUROQUEST domain, showed a reasonable internal consistency for the questionnaire. For both women and men, memory problems and sleep disorders increased significantly with age. A significant association between EUROQUEST scores and exposure to neurotoxic agents was found for workers exposed to anaesthetic gas only. In addition, EUROQUEST memory symptoms from the Reference population were found to be correlated with two memory neuropsychological tests, both for men and women. CONCLUSION: Our results showed a high internal consistency and a good convergent validity on assessed domains. Moreover, they showed a significant sensitivity to age, educational level and highlighted sensitivity to anaesthetic gas exposure.

Adult↗
PubMed2003

Comparison of measurement strategies for prospective occupational epidemiology.

In the context of a prospective assessment of exposure for epidemiology, our objective is to obtain an optimal group-based design of allocation of a fixed total number of measurements. Such a design has been described by Ashford [Ashford JR. (1958) The design of a long-term sampling programme to measure the hazard associated with an industrial environment. J R Statist Soc A; 121: 331-47]. As this strategy is not operational, we developed three series of strategies: the first based on simplifications of Ashford's strategy; the second based on a pilot study; and the third on an iterative assessment of the group specific standard deviation of exposure. These strategies are compared by simulating a day-to-day individual exposure in several industrial sites and the resulting health effect. Our criteria for comparing strategies are the mean squared error of the estimated exposure in each group weighted by the number of subjects and the mean squared error of the estimated linear regression coefficient in the dose-response relationship. Strategies relying on an iterative approach have been found to perform best whatever the circumstances, nearly as well as Ashford's optimal strategy.

Humans↗
PubMed2002

Neurobehavioral disturbances arising from occupational toluene exposure.

BACKGROUND: Neurotoxicity of long-term exposure to toluene is known at higher levels than 50 ppm and is suspected at lower levels. METHODS: A cross-sectional study carried out in two printing plants on 129 blue collar workers explored such a low level exposure of toluene. With 231 samples of ambient air, toluene concentration was estimated from 0 to 18 ppm in Plant A (offset) and from 2 to 27 ppm in Plant B (heliogravure). Outside any period of acute exposure, the workers answered a self-administered questionnaire on neurotoxic symptoms, EUROQUEST, and performed six psychometric tests on a computer-assisted version of battery NES. RESULTS: After adjustment for confounders, we found significant relationships only between present exposure and Digit Span Forwards (DSF) performance (decrement is 1 digit for 40 ppm, P=0.04) and Digit Span Backwards (DSB) performance (decrement is 1 digit for 25 ppm, P=0.01). Neurotoxic symptoms were not significantly correlated with current exposure. No association was found between estimated cumulative exposure and either psychometric performances or neurotoxic symptoms. CONCLUSION: In this study, low present exposure levels to toluene were associated with decrements of memory test performances.

Adult↗