Francesca Graziosi

Carpal tunnel syndrome and manual work: a longitudinal study.

Objective: To assess risks associated with work-related biomechanical overloads in onset/course of carpal tunnel syndrome. Methods: Workgroups with job tasks spanning different biomechanical exposures were evaluated at baseline in terms of American Conference of Governmental Industrial Hygienists hand-activity/peak force action limit and threshold limit values (TLV). Exposures of interest were “unacceptable” (hand-activity above TLV) and “borderline” (between action limit and TLV) overloads. Clinical/individual data were collected at baseline and 12 months. Results: One-year incidence of “classic/possible” carpal tunnel syndrome symptoms as defined by consensus criteria was 7.3% (153 of 2092). “Unacceptable” overload was associated with a 3-fold increased risk of onset with respect to “acceptable” load. At ordered logistic regression analysis of symptom-status variations, increased risks were recorded for “unacceptable” and “borderline” overloads. Conclusions: Effectiveness of encouraging workplace adherence to the American Conference of Governmental Industrial Hygienists recommendations deserves investigation as a possible key to wide-scale prevention.

Validation of the ACGIH TLV for hand activity level in the OCTOPUS cohort: a two-year longitudinal study of carpal tunnel syndrome

OBJECTIVES This study aimed to evaluate the risk of musculoskeletal disorders to the hand-wrist system. The American Conference of Governmental Industrial Hygienists (ACGIH) proposed threshold limit values (TLV©) based on hand activity level (HAL) and normalized peak force (PF). We validated ACGIH TLV© in OCTOPUS, a large cohort study on carpal tunnel syndrome (CTS). METHODS Industrial and service workers were followed from 2000-2003. We classified subjects with respect to action limit (AL) and TLV. Case definitions were: (i) self-reported symptoms; and (ii) combination of symptoms and positive nerve conduction studies. Poisson regression models including age, gender, body mass index, and presence of predisposing pathologies were conducted to estimate incidence rate ratios (IRR) of CTS. RESULTS There were 4097 eligible workers. Of these, 236 (5.8%) were non-responders, 2194 (53.6%) had a complete follow-up, 728 (17.8%) were lost after intermediate assessment, and 939 (22.9%) were lost after baseline. Among the 3860 subjects with complete information at baseline, 2599 (67.3%) were women [mean age 38.1 [standard deviation (SD) 9.5] years; mean body mass index (BMI) 23.8 (SD 3.9) kg/m2]. ACGIH TLV© classification predicted both CTS symptoms [IRR between AL and TLV 2.43 [95% confidence interval (95% CI) 1.77-3.33]; above TLV 3.32 (95% CI 2.34-4.72)] and CTS confirmed by nerve conduction studies [IRR between AL and TLV 1.95 (95% CI 1.21-3.16); above TLV 2.70 (95% CI 1.48-4.91)]. CONCLUSIONS We found a dose-response relationship between ACGIH TLV© classification and risk of CTS. The increased risk observed for workers exposed between AL and TLV suggests that the current AL and TLV might not be sufficiently protective.

Urinary biomarkers and low-level environmental benzene concentration: Assessing occupational and general exposure

The categories of urban workers undergoing prolonged exposure to gasoline due to vehicle emissions, evaporation and traffic fumes are considered occupationally exposed to benzene, even if at low concentrations. The aim of this study was to evaluate the specificity of unmetabolized benzene excreted in urine (UBz) and S-phenylmercapturic acid (SPMA) as biomarkers of exposure to very low levels of benzene, and to study the impact of putative individual confounders like smoking and alcohol habits, co-exposure to other toxicants and body mass index on the exposure assessment. Environmental and biological monitoring of exposure to benzene were performed in 114 Urban Policemen. The mean value of UBz in non-smokers was significantly lower than in either groups of light to moderate smokers and heavy smokers (0.24, 1.82 and 2.82 microg L(-1), respectively). On the contrary, SPMA values did not discriminate exposure resulting from smoking habits. Moreover, the concentration of UBz in non-smokers appears to be correlated with environmental benzene concentration (BenzA) (R(2)=0.13, beta=0.37, p=0.002). On the other hand, no significant correlation was found between SPMA concentration (corrected for creatinine excretion and log transformed, LogSPMA) and LogBenzA (R(2)=0.003, beta=0.05, p=0.6). Our findings reinforce previous research on the use of unmetabolized urinary benzene as a specific and sensitive biomarker of low-level exposure to benzene and confirm that smoking habits strongly influence the excretion of UBz.

Exposure to low environmental levels of benzene: evaluation of micronucleus frequencies and S-phenylmercapturic acid excretion in relation to polymorphisms in genes encoding metabolic enzymes.

An integrated approach based on environmental and biological monitoring, including the analysis of biomarkers of exposure [excretion of S-phenylmercapturic acid (S-PMA)], early biological effects [micronucleus (MN) frequency] and susceptibility (genetic polymorphisms), was applied to characterize benzene exposure in a group of 70 traffic policemen and 40 employees of the city of Bologna, Italy. Median personal benzene exposure was 6.55-fold higher for traffic policemen than for controls (P<0.0001). This higher exposure was confirmed by a significant, 2.53-fold higher S-PMA excretion in traffic policemen compared with that observed for indoor workers (P<0.0001). Median MN frequency was also significantly higher in policemen compared with indoor workers (P=0.001), emphasizing the genotoxic effect potentially associated with benzene exposure. With regard to biomarkers of susceptibility, the analysis revealed that high epoxide hydrolase (mEH) (predicted) enzyme activity was significantly correlated with a lower median MN frequency (P=0.003). A gene-gender interaction was observed for the glutathione-S-transferase M1 (GSTM1) genotype. The GSTM1-null genotype was associated with a significantly higher median MN frequency in men, not in women. Statistical analysis did not reveal any association between the presence of the protective allele, pushing the pathway towards benzene detoxification, and MN frequency or S-PMA excretion. Even though there are some limitations in the study, our results indicate that policemen are exposed to higher levels of benzene than individuals spending most of the time indoors. This higher exposure may contribute to DNA damage, suggesting an increase health risk from traffic benzene emission. Finally, a more comprehensive study is warranted in order to better elucidate the involvement of EPHX1 genotypes combination in benzene genotoxicity.

Efficacy of three face masks in preventing inhalation of airborne contaminants in dental practice.

ABSTRACT Background Up-to-date studies are needed on the protection provided by face masks used by dentists. We assessed the relative filtering efficacy of two currently used surgical face masks (one a molded mask, the other a tie-on mask) and a certified personal particulate respirator, all made by a single manufacturer. Methods The authors sprayed bicarbonate particulate against a porcelain surface (representing the patients mouth) and collected it via a mannequin head (representing the dentists head) placed 40 centimeters away and a tube with two airflow rates (0.5 cubic meters per hour and 9 m3/hour). They calculated the dry residue weight. They performed three separate runs for each mask and three runs with no mask at the two airflow rates with and without aerosol. Results With no mask (control), the authors recorded significant weight gains at both airflow rates with and without vaporization. With vaporization, the three masks were associated with different dry residue weights (P < .03 with the Kruskal-Wallis test at both flow rates), the respirator providing the lowest amount. The respirator provided an efficiency of 94 to 96 percent, compared with 90 to 92 percent and 85 to 86 percent for the molded and tie-on surgical masks, respectively. Conclusions These data provide independent evidence that a certified personal respirator can be more effective than high-quality surgical masks in dental settings. Clinical Implications Dentists should be aware that a certified particulate respirator can provide them with superior filtering protection.

Carpal tunnel syndrome and manual work: the OCTOPUS cohort, results of a ten-year longitudinal study.

OBJECTIVE The American Conference of Governmental Industrial Hygienists (ACGIH) proposed a method to assess the hand, wrist and forearm biomechanical overload based on exertions frequency (hand-activity level) and force use (normalized peak force). We applied the ACGIH threshold limit value (TLV)® method to a large occupational cohort to assess its ability to predict carpal tunnel syndrome (CTS) onset. METHODS A cohort of industrial and service workers was followed-up between 2000 and 2011. We investigated the incidence of CTS symptoms and CTS confirmed by nerve conduction studies (NCS). We then classified exposure with respect to action limit (AL) and TLV. Cox regression models including age, gender, body mass index, and presence of predisposing pathologies were conducted to estimate hazard ratios (HR) of CTS and population attributable fractions. RESULTS We analyzed data from 3131 workers [females, N=2032 (65%); mean age at baseline 39.3, standard deviation (SD) 9.4 years]. We observed 431 incident cases of CTS symptoms in 8000 person-years and 126 cases of CTS confirmed by NCS in 8883 person-years. The ACGIH TLV® method predicted both CTS symptoms [HR between AL and TLV 2.18, 95% confidence interval (95% CI) 1.86-2.56; above TLV 2.07, 95% CI 1.52-2.81] and CTS confirmed by NCS (HR between AL and TLV 1.93, 95% CI 1.38-2.71; above TLV 1.95, 95% CI 1.27-3.00). About one third of CTS cases were attributable to exposure levels above the AL. CONCLUSIONS The ACGIH TLV® method predicted the risk of CTS, but the dose-response was flat above the AL; a fine-tuning of the proposed thresholds should be considered.

A case report of vibration-induced hand comorbidities in a postwoman

BackgroundProlonged exposure to hand-transmitted vibration is associated with an increased occurrence of symptoms and signs of disorders in the vascular, neurological and osteoarticular systems of the upper limbs. However, the available epidemiological evidence is derived from studies on high vibration levels caused by vibratory tools, whereas little is known about possible upper limb disorders caused by chronic exposure to low vibration levels emitted by fixed sources.Case presentationWe present the case of a postwoman who delivered mail for 15 years using a low-powered motorcycle. The woman was in good health until 2002, when she was diagnosed with bilateral Raynauds phenomenon. In March 2003 a bilateral carpal tunnel syndrome was electromyographically diagnosed; surgical treatment was ineffective. Further examinations in 2005 highlighted the presence of chronic tendonitis (right middle finger flexor).Risk assessmentFrom 1987, for 15 years, our patient rode her motorcycle for 4 h/day, carrying a load of 20-30 kg. For about a quarter of the time she drove over country roads. Using the information collected about the tasks carried out every day by the postwoman and some measurements performed on both handles of the motorcycle, as well as on both iron parts of the handlebars, we reconstructed the womans previous exposure to hand-arm vibration. 8-hour energy-equivalent frequency weighted acceleration was about 2.4 m/s2. The lifetime dose was 1.5 × 109(m2/s4)hd.ConclusionsThe particular set of comorbidities presented by our patient suggests a common pathophysiological basis for all the diseases. Considering the level of exposure to vibrations and the lack of specific knowledge on the effects of vibration in women, we hypothesize an association between the work exposure and the onset of the diseases.

Effects of 90 min of manual repetitive work on skin temperature and median and ulnar nerve conduction parameters: A pilot study in normal subjects

To test whether the influence of manual activity should be considered when interpreting the results of nerve conduction study (NCS) of the upper limbs performed during work shifts, we evaluated the short-term effect of 90-min repetitive manual work on NCS parameters. Twenty-eight healthy volunteers underwent NCS of the dominant limb at the end of an interview (T(0)), after a 30-min rest in sitting position (T(1)) and after performing a standardized 90-min manual task (T(2)). The task was designed to simulate typical assembly and packing activities. No significant differences were observed for skin temperature (Ts) and NCS parameters between T(0) and T(1). Significantly (p < 0.001) higher Ts mean values were found at T(2) as compared to the previous tests for both females and males. The regression analysis showed an association between temperature variation and nerve conduction velocity values for the median and ulnar nerve at T(2) as compared to T(1). In females, a reduction of the mean sensory nerve action potential (SNAP) amplitude at T(2) was recorded, whereas an opposite trend was observed among males. Manual work is able to influence hand Ts and to modify NCS parameters. SNAP amplitudes changes suggest gender differences in peripheral nerve characteristics that deserve further investigation.

Knee osteoarthritis in a chestnut farmer – Case Report

INTRODUCTION Several studies have dealt with the issue of professional risk factors and onset of knee osteoarthritis (OA). In particular, occupational epidemiological studies have provided evidence that activities resulting in biomechanical overload may be linked with an increased risk of knee OA - also among farmers. To our knowledge, no cases of knee OA among chestnut farmers have been reported in the literature. CASE REPORT We report the case of a 70-year-old Caucasian male who has worked for more than 50 years on a chestnut farm. In 2007, an X-ray and a MRI, performed after a workplace accident to his left knee, showed the presence of knee OA. His job required a range of repetitive tasks, such as squatting, kneeling, climbing, walking on sloping terrain, assuming uncomfortable postures, and lifting and carrying heavy loads for the great majority of the working day. All the aforementioned tasks are known occupational risk factors for knee OA. Regarding individual risk factors, at the time of the first diagnosis of knee OA, the worker was 64-years-old with a body mass index of 26.5 kg/m2. He reported no cases of arthritis among his relatives and no sports playing on his part. In addition, his medical history revealed the presence of two minor lumbar disc herniations and tendinitis of the long head of the biceps. CONCLUSION Considering the lack of major individual risk factors for knee OA, it is reasonable to suppose that five decades of exposure to biomechanical overload as a chestnut farmer was a relevant risk factor for the onset of the disease.

Carpal tunnel syndrome and manual work: the first 3 years of a longitudinal study

Objectives Evidence on occupational determinants of Carpal Tunnel Syndrome (CTS) mainly derived from cross-sectional or retrospective studies. We conducted a cohort study to investigate the association between biomechanical occupational exposures and CTS symptoms. Methods A longitudinal study on different groups of industrial and service workers started in 2000; outcome measures were conducted after one and 2 years. Exposure assessment was conducted for each job task according to American Conference of Governmental Industrial Hygienists (ACGIH) recommendations; biomechanical loads were classified as: 1) below the Action Limit (AL); 2) between the AL and the Threshold Limit Value (TLV); 3) above the TLV. Case definition was based on self-reported symptoms of CTS and followed the Consensus Criteria for the Classification of CTS in Epidemiologic Studies. Results After exclusions, 2472 workers entered our analyses. Subjects exposed between AL and TLV (adjusted IRR 2.33, 95% CI 1.76 to 3.07) and above TLV (adjusted IRR 3.07, 95% CI 2.33 to 4.05) showed an increased risk of CTS symptoms. However, while incidence of CTS symptoms dramatically increased by exposure status among females (adjusted incidence below the AL: 4.9/100 pyears, 95% CI 3 to 6.3; above the TLV: 17.7/100 pyears, 95% CI 12.8 to 22.7), a very small increase was found for males (adjusted incidence below the AL: 2.1/100 pyears, 95% CI 1.2 to 3.6; above the TLV: 3.8/100 pyears, 95% CI 2.1 to 6.7). Conclusions We found a dose-response relationship between biomechanical exposure classified according to ACGIH and incidence of CTS symptoms. However, sex stratified analyses uncovered major differences between gender; these findings support the hypothesis that different exposure limits should be considered for males and females