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Background: Occupational contact dermatitis (OCD) is frequent in the workplace. Objectives: To provide recent data on the epidemiology of OCD in Italy. Methods: This multicenter retrospective study, conducted from 1996 to 2016, included patients with suspected allergic contact dermatitis (ACD) patch tested in the departments comprising the North-East Italy Contact Dermatitis Group. Results: We studied 18 859 workers with a diagnosis of contact dermatitis (CD), of which 10.4% were recognized as being of professional origin. OCD declined from 1996 to 2011–2013 and increased in 2014–2016. The overall prevalence of both CD and OCD was higher in women compared to men, but the share of OCD of the total CD was greater for men compared to women. A history of atopic dermatitis was less frequent in workers with OCD than in non-OCD patients (5.8% vs 8.6%). Hairdressers were the youngest profession (27.1 ± 11.7 years). Hands were the primary site of involvement in patients with OCD (76.6%). The five highest risk occupations for OCD were hairdressers, cooks, metalworkers, chemical industry workers, and construction workers. Conclusions: OCDs have a relevant impact in our region, mainly for five job categories, and the increase in the last 3 years suggests the need to improve preventive measures.

BACKGROUND: Methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI) (Kathon® CG) is a common preservative used in industrial products, owing to its strong biocide effect. Contact allergy to MCI/MI has been reported in different occupations, including mechanics, hairdressers and healthcare workers. OBJECTIVE: To retrospectively analyse the temporal trend of MCI/MI sensitization in north-eastern Italy and to evaluate the associations with occupations in our geographical area. METHODS: From 1996 to 2016, 27 381 patients with suspected allergic contact dermatitis were patch tested in eight departments of Dermatology or Occupational Medicine in north-eastern Italy. Individual characteristics were collected through a standardized questionnaire. RESULTS: The overall prevalence of MCI/MI sensitization was 4.2%, with the highest prevalence found in women and in patients younger than 25 years. MCI/MI sensitization was significantly associated with atopic eczema (OR: 1.34, 95% CI: 1.10-1.70), hand/forearm dermatitis (OR: 1.20, 95% CI: 1.05-1.36) and face dermatitis (OR 1.30, 95% CI: 1.10-1.40). There was a significant association between MCI/MI sensitization and chemical processing workers (OR 1.74, 95% CI: 1.03-2.94), while mechanics and healthcare workers resulted more sensitized to this hapten only in the last 3 years. CONCLUSIONS Sensitization to MCI/MI is rising in the last years in Triveneto region, the 'epidemic' of sensitization to MCI/MI is mainly driven by extra-occupational dermatitis, and sensitization in some occupational groups is emerging only in the last years. A full labelling is compulsory for all products that contain isothiazolinones, to permit to identify the culprit agent.

Contact dermatitis in construction workers (CWs) is frequent due to the widespread exposure to sensitizing substances and irritating agents and the wet and cold working conditions.Background: Contact dermatitis in construction workers (CWs) is frequent due to the widespread exposure to sensitizing substances and irritating agents and the wet and cold working conditions. Objective: Our objectives were to evaluate contact dermatitis characteristics among CWs who underwent patch test in northeastern Italy and to identify related allergens. Methods: Seven hundred ninety-five CWs were studied and their data were compared to 2.099 male white-collar workers. The associations between patch test results and occupations were assessed by multivariate logistic regression analysis. Incidence data were calculated from 1996 to 2016. Results: CWs with confirmed occupational dermatitis presented an increased risk to be sensitized to potassium dichromate [OR 3.1 (95%IC 2.0-4.8)], to thiurams [OR 8 .6 (95%IC 4.0-18.4)], and to epoxy resins [OR 12.7 (95%IC 6.1-26.4)]. Sensitization to chromate decreased significantly after 2004, following EU regulation of chromate content in concrete, while sensitization to epoxy resins and thiurams increased. The overall incidence of occupational contact dermatitis in CWs decreased significantly. Conclusion: Our study demonstrated the effectiveness of EU regulations in reducing chromate sensitization in CWs and the overall incidence of occupational contact dermatitis. However, sensitization to other haptens is increasing, though improvement of protective measures is compulsory.

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Background: Hairdressers are at high risk of contact dermatitis (CD) due to skin exposure to numerous irritants and haptens in hair products in combination with frequent wet work. Objectives: To investigate the characteristics and incidence of CD among hairdressers in north-eastern Italy. Methods: A total of 324 hairdressers who had been examined and patch tested in north-eastern Italy from 1996 to 2016 were retrospectively identified, and compared with 9669 matched controls. Sensitization to allergens of the hairdressing series was analysed among hairdressers attending an occupational medicine clinic in Trieste, Italy. Incidence data were calculated from 1999 to 2016. Results: Sensitization to p-phenylenediamine, thiuram mix, and N-isopropyl-N'-phenyl-p-phenylenediamine was significantly associated with hairdressing and with hand/forearms dermatitis. Frequent sensitizers from hairdressing series were ammonium persulfate, toluene-2,5-diamine, and p-aminobenzene. The overall incidence of CD declined from 2003 (31.7 cases/10 000 workers) to 2016 (20.8 cases/10 000 workers). Conclusions: Sensitization to several haptens was significantly associated with hairdressing. The incidence of CD among hairdressers in north-eastern Italy has declined in recent years, but is still high. Preventive efforts are needed to reduce the burden of CD in this professional group.

MnFe2O4 nanoparticles (NPs) are commonly produced in some occupational settings and may reach high concentration in activities such as arc-welding or ferroalloy metallurgy. Manganese is an essential cofactor in enzyme activities but it has been demonstrated that long-term exposure to excessive levels can lead to “manganism”, a neurodegenerative disease resembling Parkinson features. Inhaled NPs deposit partially in pharynx and nasopharynx and may reach the central nervous system through the olfactory nerve, which is completely enveloped by the meningeal membranes throughout its course from the nasal cavity to the olfactory bulb or through the trigeminal nerves. This study investigated in vitro the transmeningeal absorption of 50 nm MnFe2O4NPs, using excised porcine meninges mounted on Franz diffusion cells. We tested two donor solutions: the first containing MnFe2O4NPs (2.0 g/L) and the second obtained by the ultrafiltration of the first one, in order to test only the NPs water soluble fraction. Each experiment was carried separately for 4 h. Results showed that no Mn flux permeation through the meninges occurred, since only trace of the metal was found in receivers solutions of cells exposed to MnFeNPs (5.5 ± 2.2 ng/cm2), ultrafiltered solution (3.5 ± 1.5 ng/cm2) and blank cells. (2.1 ± 0.6 ng/cm2) (mean and SE). Differences did not reach the statistical significance. Our study shows – for the first time - that MnFe2O4NPs penetrate the meningeal membrane in a negligible amount, thus making unlikely the hypothesis of a transcellular and paracellular absorption through the olfactory nerve but not excluding the hypothesis of an active intraneuronal absorption.

Exposure to laboratory animals (LA) can cause allergic sensitization and symptoms as rhinitis, conjunctivitis, asthma, anaphylaxis and dermatitis. In 2000, a program was instituted at Trieste Universities to decrease LA allergy among scientists and technicians working with animals. The aim of our study was to investigate LA allergy in workers exposed to LA from 2001 to 2016, and to verify the effects of a preventive program. Four hundred sixty seven people underwent pre-employment screening for a job with laboratory animals at Universities of Trieste consisting in a medical examination, a full respiratory and allergy anamnesis, using a standardized questionnaire, skin prick test with common and occupational allergens, and spirometry. Every year, each worker repeated the medical examination and underwent again tests and questionnaire. Each worker can ask for a medical examination and skin prick test, in case of unset of symptoms. Logistic multivariate analysis and generalized equation estimation were use, to verify factors associated to LA allergy. Sensitization to LA decreased in years, going from 25.6% in 2001-2004 to 8.2% in 2013-2016 (p 0.001). Multivariate logistic regression analysis confirmed the role of atopy by prick test (OR = 6; IC95% 2.2-16.6), of common allergic symptoms (OR = 2.9; IC95% 1.4-6.39) and of calendar periods. No association was found between LA allergy, years, and hours of exposure. Our study demonstrated a significant reduction of LA allergy after the application of a preventive program.

Highlights After the introduction of the EU regulatory interventions, nickel sensitization decreased significantly in the group of females aged ≤25 years. Women born between 1966 and 1975 presented the higheest prevalence of sensitization to nickel, then prevalence of sensitization gradually decreased with a minimum in more recent years. Nickel sensitization is higher in Italian patients compared to people living in other EU coutries. Additional interventions are needed to address nickel sensitization.

(1) Background: Fragrance sensitization is common in Italy and their constituents are used in many cosmetics and detergents. The objective of the study was to analyze the temporal trend of sensitivity to fragrance mix-1 in northeastern Italy and to evaluate gender differences, (2) Methods: From 1996 to 2016, 27,381 consecutive patients with suspected allergic contact dermatitis were patch tested. Individual characteristics were collected through a standardized questionnaire in six departments of dermatology or occupational medicine, (3) Results: The overall prevalence of sensitization to fragrance mix-1 was 7.3%, the prevalence was significantly higher in women (7.7%) than in men (6.3%). From 1996 to 2016, we observed an increase of this sensitization, ranging from 6.2% to 7.7% in males and from 7.2% to 9.1% in females, (4) Conclusions: Our study showed that contact allergy to fragrance mix-1 is important in both sexes and prevalence is increasing over time, despite the introduction of new fragrances with lower sensitization potential. There is the need to reduce the use of fragrances mix-1 to stop the increase of sensitization in exposed subjects.

BACKGROUND: Mechanics are at higher risk to develop occupational skin diseases from exposure to irritants, oils, greases, preservatives, and metals. AIMS: The aim of the study was to investigate contact dermatitis in mechanics who underwent patch test in Northeastern Italy and compare them with white-collar workers (WCW). SUBJECTS AND METHODS: From 1996 to 2016, 27,381 patients with suspected allergic contact dermatitis were patch tested in Northeastern Italy; in this group, 1270 mechanics were studied. Odds ratios (ORs) and 95% confidence interval (CI), adjusted by age and sex, were calculated assuming WCW as the reference category (n = 6933). RESULTS: Mechanics represented 4.6% of the population tested. Their mean ± SD age was 36.1 ± 11.2 years. Compared with WCW, they were found to have an increased risk of occupational dermatitis (OR = 14.4; 95% CI = 11.6-18) and hand/forearm dermatitis (OR = 2.5; 95% CI = 2.3-2.9). They presented an increased risk of sensitization to epoxy resin (OR = 2.7; 95% CI = 1.5-4.8), to thiurams (OR = 2.4; 95% CI = 1.5-3.8), to 2-mercaptobenzothiazole (OR = 1.9; 95% CI = 1.1-3.4), and to diaminodiphenylmethane (OR = 1.7; 95% CI = 1.1-2.5). CONCLUSIONS: Compared to WCW, mechanics were found to be at higher risk to develop occupational contact dermatitis, associated mainly to sensitization to epoxy resin and rubber accelerators.

Nickel nanoparticles (NiNPs) represent a new type of occupational exposure because, due to the small size/high surface, they can release more Ni ions compared to bulk material. It has been reported a case of a worker who developed sensitization while handling nickel nanopowder without precautions. Therefore there is the need to assess whether the skin absorption of NiNPs is higher compared to bulk nickel. Two independent in vitro experiments were performed using Franz diffusion cells. Eight cells for each experiment were fitted using intact and needle-abraded human skin. The donor phase was a suspension of NiNPs with mean size of 77.7 ± 24.1 nm in synthetic sweat. Ni permeated both types of skin, reaching higher levels up to two orders of magnitude in the damaged skin compared to intact skin (5.2 ± 2.0 vs 0.032 ± 0.010 μg cm(-2), p = 0.006) at 24 h. Total Ni amount into the skin was 29.2 ± 11.2 μg cm(-2) in damaged skin and 9.67 ± 2.70 μg cm(-2) in intact skin (mean and SD, p = 0.006). Skin abrasions lead to doubling the Ni amount in the epidermis and to an increase of ten times in the dermis. This study demonstrated that NiNPs applied on skin surface cause an increase of nickel content into the skin and a significant permeation flux through the skin, higher when a damaged skin protocol was used. Preventive measures are needed when NiNPs are produced and used due to their higher potential to enter in our body compared to bulk nickel.

Titanium dioxide nanoparticles (TiO2NPs) suspensions (concentration 1.0 g/L) in synthetic sweat solution were applied on Franz cells for 24 h using intact and needle-abraded human skin. Titanium content into skin and receiving phases was determined. Cytotoxicity (MTT, AlamarBlue® and propidium iodide, PI, uptake assays) was evaluated on HaCat keratinocytes after 24 h, 48 h, and seven days of exposure. After 24 h of exposure, no titanium was detectable in receiving solutions for both intact and damaged skin. Titanium was found in the epidermal layer after 24 h of exposure (0.47 ± 0.33 ?g/cm2) while in the dermal layer, the concentration was below the limit of detection. Damaged skin, in its whole, has shown a similar concentration (0.53 ± 0.26 ?g/cm2). Cytotoxicity studies on HaCaT cells demonstrated that TiO2NPs induced cytotoxic effects only at very high concentrations, reducing cell viability after seven days of exposure with EC50s of 8.8 × 10-4 M (MTT assay), 3.8 × 10-5 M (AlamarBlue® assay), and 7.6 × 10-4 M (PI uptake, index of a necrotic cell death). Our study demonstrated that TiO2NPs cannot permeate intact and damaged skin and can be found only in the stratum corneum and epidermis. Moreover, the low cytotoxic effect observed on human HaCaT keratinocytes suggests that these nano-compounds have a potential toxic effect at the skin level only after long-term exposure. © 2015 by the authors; licensee MDPI, Basel, Switzerland.

Silver nanoparticles (AgNPs) can come in contact with human oral mucosa due to their wide use in food industry and hygiene devices. We evaluate transmucosal absorption of 19 nm AgNPs using excised porcine buccal mucosa applied on Franz diffusion cells. Two donor solutions were used: one containing AgNPs (0.5 g/L) and one derived from the ultrafiltration of the former and containing only Ag in its soluble form. Experiments were carried out separately for 4 h. Silver flux permeation was demonstrated through oral mucosa, showing similar values for AgNPs (6.8±4.5 ng cm(-2) h(-1)) and Ag ions (5.2±4.3 ng cm(-2) h(-1)). Our study demonstrates that silver can permeate the oromucosal barrier and that absorption is substantially due to Ag ions, since no permeation difference was found using the two solutions. Mucosal absorption has to be considered in further risk assessment studies.

Skin absorption and toxicity on keratinocytes of cobalt oxide nanoparticles (Co3O4NPs) have been investigated. Co3O4NPs are commonly used in industrial products and biomedicine. There is evidence that these nanoparticles can cause membrane damage and genotoxicity in vitro, but no data are available on their skin absorption and cytotoxicity on keratinocytes. Two independent 24 h in vitro experiments were performed using Franz diffusion cells, using intact (experiment 1) and needle-abraded human skin (experiment 2). Co3O4NPs at a concentration of 1000 mg/L in physiological solution were used as donor phase. Cobalt content was evaluated by Inductively Coupled–Mass Spectroscopy. Co permeation through the skin was demonstrated after 24 h only when damaged skin protocol was used (57 ± 38 ng·cm−2), while no significant differences were shown between blank cells (0.92 ± 0.03 ng cm−2) and those with intact skin (1.08 ± 0.20 ng·cm−2). To further investigate Co3O4NPs toxicity, human-derived HaCaT keratinocytes were exposed to Co3O4NPs and cytotoxicity evaluated by MTT, Alamarblue® and propidium iodide (PI) uptake assays. The results indicate that a long exposure time (i.e., seven days) was necessary to induce a concentration-dependent cell viability reduction (EC50 values: 1.3 × 10−4 M, 95% CL = 0.8–1.9 × 10−4 M, MTT essay, 3.7 × 10−5 M, 95% CI = 2.2–6.1 × 10−5 M, AlamarBlue® assay) that seems to be associated to necrotic events (EC50 value: 1.3 × 10−4 M, 95% CL = 0.9–1.9 × 10−4 M, PI assay). This study demonstrated that Co3O4NPs can penetrate only damaged skin and is cytotoxic for HaCat cells after long term exposure.

Background Colophonium is a natural substance derived from Pineaceae trees. It is used in a wide range of consumer and occupational products because of its tackiness, and is a known sensitizer. Objectives To analyse the temporal trend of contact allergy to colophonium in north-eastern Italy, and to evaluate the associations with occupations in our geographical area. Methodology From 1996 to 2016, 27 381 patients with suspected allergic contact dermatitis were patch tested in north-eastern Italy. Individual characteristics were documented by use of a standardized questionnaire in 6 departments of dermatology or occupational medicine. Results The overall prevalence of colophonium sensitization was 1.67%; the prevalence was significantly higher in women (1.75%) than in men (1.49%). No significant differences among departments were observed. We found significant associations between colophonium sensitization and being a student (odds ratio [OR] 4.64; 95% confidence interval [CI]: 1.04-20.6), being a farmer or fishermen (OR 3.63; 95%CI: 1.21-10.84), being a housekeeper (OR 2.02; 95%CI: 1.08-3.77), and being retired (OR 2.06; 95%CI: 1.08-3.92). Conclusion Our study showed that contact allergy to colophonium is still relevant in north-eastern Italy. The frequency of sensitization has dropped significantly over a period of 10 years, but students and farmers/fishermen still have sensitization prevalences above 3.5%. Our results are in line with European data.

Background Occupational skin diseases are often responsible for sick leave or job changes, affect mostly young subjects, are costly to society and have been reported as significant predictor of unemployment. Objectives To assess, over time, the course of occupational hand dermatitis (OHD) after a specific training, by means of follow-up visits and TEWL measurement, to evaluate skin barrier integrity and if preventive measures for hand skin care provided may influence the course of the disease. Methods Workers with a diagnosis of OHD from January 2011 to December 2013 were contacted by telephone, filled in a questionnaire (NOSQ-2002) and were invited to a training course on prevention of skin dermatitis, and to a new clinical evaluation with TEWL measurement. Workers who joined the training programme were asked to undergo a new evaluation after 3 months. A total of 65 subjects without contact dermatitis were recruited as control group. Results One hundred and one subjects from 143 workers, who were contacted, filled in the questionnaire. Sixty-five of them followed the training course and underwent a new clinical evaluation withTEWL measurements. Ongoing symptoms of subjects decreased from 60.0% to 42.3% 3 months after the training, and the subgroup which strictly adhered to the recommendations given achieved better results (61.9% of symptoms improvement when compared to 29.0% obtained in subjects with partial adhesion to the protocol). TEWL values changed from 21.3 ± 9.6 to 18.6 ± 7.2 g/m²/h (P = 0.001) on the hands and from 16.6 ± 9.0 to 10.5 ± 4.6 g/m²/h (P = 0.001) on the forearm, confirming the skin barrier improvement. Conclusions Our secondary prevention intervention was effective, leading to a reduction in clinical signs of dermatitis. TEWL measurement is a useful tool to evaluate skin integrity, mostly in apparently healthy skin, which may have a compromised barrier function, resulting in an exacerbation of the dermatitis.

The incidence of OCD (occupational contact dermatitis) in different European Countries and USA ranges between 0.5 and 1.9 cases per 1000 workers per year. 1,2,3 OCD is lowering in the last 10-15 years, with incidence rate that varies between 1.2 to 0.56 cases per 1000 person-years from 1993 to 1996 in Germany 1,3 and from 0.29 to 0.1 cases per 1000 from 1997 to 2008 in a Czech study.4 Incidence of notified occupational skin diseases for health care workers (HCWs) was 3.1 cases per 1000 workers per year in USA, 1.5 in Bavaria, 1.5 in Denmark (only nurses), 0.4 in Northem Bavaria and 0.1-0.29 in Czech Republic.4 This article is protected by copyright. All rights reserved.

Objective The aim of this study was to investigate the performance of four frequency weightings for hand-transmitted vibration to predict the incidence of vibration-induced white finger (VWF). Methods In a longitudinal study of vibration-exposed forestry and stone workers (N=206), the incidence of VWF was related to measures of vibration exposure expressed in terms of 8-hour frequency-weighted energy-equivalent root-mean-square (rms) acceleration magnitude [A(8)] and years of follow-up. To calculate A(8), the rms acceleration magnitudes of vibration were weighted by means of four frequency weightings: (i) W(subscript h) (the frequency weighting specified in ISO 5349-1:2001); (ii) W(subscript h-bl) (the band-limiting component of W(subscript h)); (iii) W(subscript hf) (a frequency weighting based on finger vibration power absorption); and (iv) W(subscript hT) (a frequency weighting based on a Japanese study of VWF prevalence). The relations of VWF to alternative measures of vibration exposure were assessed by the generalized estimating equations (GEE) method to account for the within-subject dependency of the observations over time. Results Data analysis with a GEE logistic model and a measure of statistical fit suggested that calculating A(8) by weighting the tool rms accelerations with W(subscript h-bl) gave better predictions of the cumulative incidence of VWF than the other alternative measures of daily vibration exposure. Values of A(8) derived from the currently recommended ISO frequency weighting W(subscript h) produced poorer predictions of the incidence of VWF than those obtained with frequency weightings W(subscript hf) or W(subscript hT). Conclusions This prospective cohort study suggests that measures of daily vibration exposure which give relatively more weight to intermediate and high frequency vibration are more appropriate for assessing the probability of VWF.

The concentrated nicotine in e-cigarette refill liquids can be toxic if inadvertently ingested or absorbed through the skin. Reports of poisonings due to accidental ingestion of nicotine on refill liquids are rapidly increasing, while the evaluation of nicotine dermally absorbed still lacks. For that reason we studied transdermal nicotine absorption after the skin contamination with e-liquid. Donor chambers of eight Franz diffusion cells were filled with 1 mL of 0.8 mg/mL nicotine e-liquid for 24 h. The concentration of nicotine in the receiving phase was determined by high-performance liquid chromatography (LOD:0.1 μg/mL). Nicotine was detectable in receiving solution 2 h after the start of exposure and increased progressively. The medium flux calculated was 4.82 ± 1.05 μg/cm(2)/h with a lag time of 3.9 ± 0.1 h. After 24 h, the nicotine concentration in the receiving compartment was 101.02 ± 22.35 μg/cm(2) corresponding to 3.04 mg of absorbed nicotine after contamination of a skin surface of 100 cm(2). Skin contamination with e-liquid can cause nicotine skin absorption: caution must be paid when handling refill e-liquids.

Silver nanoparticles (AgNPs) are commonly used in antiseptic sprays and mist and can easily come in contact with the mucosa of the upper airways. The intranasal pathway represents the only direct connection between the external environment and the brain structures, which traditionally are considered well protected. Much is known regarding drugs absorption through this route, but toxicological knowledge is scant. The olfactory bundles are surrounded by meningeal sheets in their course from the nasal mucosa to the olfactory bulb. This study investigated in vitro the transmeningeal absorption of 19 nmAgNPs, using excised porcine meninges mounted on Franz diffusion cells. We used two donor solutions: the first containing AgNPs (0.5 g/L) and the second containing only the water-soluble silver species derived from the ultrafiltration of the first one. Each experiment was carried separately for 2 hours. Results showed silver flux permeation through the meninges, with similar values in both experiments (0.78 ± 0.71 ng cm-2 h-1 and 0.73 ± 0.43 ng cm-2 h-1, for AgNPs and Ag ions respectively, mean and SD). Our study demonstrate that the meningeal barrier is permeable to silver and silver ions, when is applied in the nanoparticles form. This could lead to neurotoxic and neurodegenerative effects, which are now emerging in the scientific literature. Metal nanoparticles are commonly encountered in working scenarios, but their behavior in physiological media is different. Therefore the toxicological potential of metal NPs is heterogeneous and requires further efforts to be assessed on a case by case basis.

OBJECTIVE: This cohort study aims to compare the performance of alternative frequency weightings of hand-transmitted vibration (HTV) for the assessment of the exposure–response relationships for neurosensory disorders and reduced work ability among HTV-exposed workers. METHODS: In a 3-year follow up study, the occurrence of neurosensory symptoms and reduced work ability, and the response to quantitative sensory testing (grip force, manipulative dexterity, touch sensation) were investigated in 249 HTV-exposed workers and 138 healthy controls. Among the HTV-exposed workers, the sensory outcomes were related to measures of daily vibration exposure expressed in terms of 8-hour energy-equivalent frequency-weighted acceleration magnitude [A(8)]. To calculate A(8), the acceleration magnitudes of vibration were weighted by means of four alternative frequency weightings of HTV. RESULTS: The occurrence of neurosensory symptoms, reduced work ability, and abnormalities of sensory tests was greater among the HTV-exposed workers than the controls. Among the HTV-exposed workers, the deterioration of neurosensory outcomes and the reduction of work ability increased on par with the measures of vibration exposure. Exposure–response models revealed that the four alternative frequency weightings of HTV provided the same predictions for the probability of finger numbness among the exposed workers (observed 36% versus predicted 32%). CONCLUSIONS: The findings of this study revealed significant dose–response relationships between measures of vibration exposure, sensory disorders, and reduced work ability among the HTV-exposed workers. There were no differences in the prediction of finger numbness between measures of vibration exposure calculated with alternative frequency weightings of HTV.

The aim of the study was to evaluate percutaneous penetration of platinum and rhodium nanoparticles (PtNPs: 5.8 ± 0.9 nm, RhNPs: 5.3 ± 1.9 nm) through human skin. Salts compounds of these metals are sensitizers and some also carcinogenic agents. In vitro permeation experiments were performed using Franz diffusion cells with intact and damaged skin. PtNPs and RhNPs, stabilized with polyvinylpyrrolidone, were synthesized by reduction of Na2PtCl6 and RhCl3·3H2O respectively. Suspensions with a concentration of 2.0 g/L of PtNPs and RhNPs were dispersed separately in synthetic sweat at pH 4.5 and applied as donor phases to the outer surface of the skin for 24 h. Measurements of the content of the metals in the receiving solution and in the skin were performed subsequently. Rhodium skin permeation was demonstrated through damaged skin, with a permeation flux of 0.04 ± 0.04 μg cm−2 h−1 and a lag time of 7.9 ± 1.1 h, while no traces of platinum were found in receiving solutions. Platinum and rhodium skin- analysis showed significantly higher concentrations of the metals in damaged skin. Rh and Pt applied as NPs can penetrate the skin barrier and Rh can be found in receiving solutions. These experiments pointed out the need for skin contamination prevention, since even a minor injury to the skin barrier can significantly increase penetration.

Objectives This study investigated the effect of hand elevation on reductions in finger blood flow (FBF) induced by hand-transmitted vibration. Methods Fourteen males attended six sessions on six separate days, with a control sessions and a vibration session (125-Hz vibration at 44 ms 2 r.m.s.) with the right hand supported at each of three elevations: 20 cm below heart level (HL), at HL, and 20 cm above HL. Finger blood flow on the left and right hand was measured every 30 s during each 25-minute session comprised of five periods: (i) no force and no vibration (5 minutes), (ii) 2-N force and no vibration (5 minutes), (iii) 2-N force and vibration (5 minutes), (iv) 2-N force and no vibration (5 minutes), and (v) no force and no vibration (5 minutes). Results Without vibration, FBF decreased with increasing elevation of the hand. During vibration of the right hand, FBF reduced on both hands. With elevation of the right hand, the percentage reduction in FBF due to vibration (relative to FBF on the same finger at the same elevation before exposure to vibration) was similar on the middle and little fingers of both hands. After cessation of vibration, there was delayed return of FBF with all three hand heights. Conclusions Vibration of one hand reduces finger blood flow on both exposed and unexposed hands, with the reduction dependent on the elevation of the hand. The mechanisms responsible for vibration-induced reductions in FBF seem to reduce blood flow as a percentage of the blood flow without vibration. Tasks requiring the elevation of the hands will be associated with lower FBF, and the FBF will be reduced further if there is exposure to hand-transmitted vibration.

Purpose – To investigate the relationships between low back symptoms and alternative measures of external dose and internal spinal dose in professional drivers exposed to whole body vibration (WBV). Methods – The occurrence of low back symptoms were investigated in a cohort of 537 drivers over a two-year follow up period. Low back pain (LBP), individual characteristics, and work-related risk factors were investigated with a structured questionnaire. Exposure to WBV was evaluated by means of measures of external dose (daily vibration exposure in terms of either equivalent continuous acceleration over an eight-hour period (A(8)) or vibration dose value according to the EU Directive on mechanical vibration) and measures of internal lumbar load (daily compressive dose Sed and risk factor R according to ISO/CD 2631-5 2014). Results – In the drivers’ cohort, the cumulative incidence of 12-month low back outcomes was 16.8% for LBP, 9.3% for chronic LBP, and 21.8% for sciatic pain. The measures of internal spinal load were better predictors of the occurrence of low back symptoms than the measures of daily vibration exposure. A two-fold increase in the risk estimates for low back outcomes was found in the upper quartile of the R factor (0.41-0.72 units) compared to the lower one (0.07-0.19 units). Conclusions – In this prospective cohort study, measures of internal spinal dose performed better than measures of daily vibration exposure (external dose) for the prediction of low back outcomes in professional drivers. The ISO boundary values of the risk factor R for low and high probabilities of adverse health effects on the lumbar spine tend to underestimate the health risk in professional drivers.

Objectives This study investigated whether reductions in finger blood flow (FBF) during and after vibration are similarly dependent on the magnitude and duration of vibration. Methods FBF on the left and right hand was measured every minute during, and for 1 hour following, exposure of the right hand to one of three magnitudes of 125-Hz sinusoidal vibration (0, 22, or 88 ms 2 r.m.s.) for one of two durations (7.5 or 15 minutes). Each session comprised five periods: (i) no force and no vibration (5 minutes), (ii) 2-N force and no vibration (5 minutes), (iii) 2-N force and vibration (7.5 or 15 minutes), (iv) 2-N force and no vibration (5 minutes), and (v) no force and no vibration (60 minutes). Results Both magnitudes and durations of vibration reduced FBF in the exposed and unexposed hands, both during and after vibration. With increased magnitude of vibration, there was increased vasoconstriction in all fingers during and after exposure, and longer recovery times after vibration exposure. With increased duration of vibration, there were no changes in vascular responses during exposure but increased vasoconstriction after exposure and prolonged recovery times. With the higher vibration magnitude, the reduction in FBF during exposure was correlated with the time taken to recover after exposure. Conclusions Subjects with greater reduction in blood flow during vibration exposure also have stronger and longer vasoconstriction during subsequent recovery. The correlation between vascular changes during and after vibration exposure suggests similar mechanisms control FBF during and after vibration exposure.

Objectives Finger blood flow is reduced by hand-transmitted vibration but there has been little study of the peripheral vascular response to repetitive mechanical shocks. This study investigated how reductions in finger blood flow depend on shock repetition rate and the peak and rms magnitude of acceleration. Methods Subjects attended seven sessions: six with repetitive mechanical shocks and a control session with no shocks. Each session comprised five successive 5-min periods: (1) no force and no vibration, (2) force and no vibration, (3) force and vibration, (4) force and no vibration and (5) no force and no vibration. During the second– fourth periods, the palm of the right hand applied 2-N force to a vibrator. During the third period, a 125-Hz mechanical shock was applied with one of four repetition rates (1.3, 5.3, 21 or 83.3/s) and one of three acceleration magnitudes (2.5, 5 or 10 ms-2 rms, unweighted). Finger blood flow was measured every 30 s in the middle and little fingers of the right (exposed) hand and the left (unexposed) hand. Results Different repetition rates (1.3–83.3 s-1) and different peak magnitudes (10–88 ms-2 peak) but the same rms acceleration (10 ms-2 rms) caused similar decreases in blood flow in fingers on exposed and unexposed hands. Shocks with a 83.3 s-1 repetition rate, peak magnitude of 10 ms-2 and rms acceleration of 10 ms-2 provoked greater reduction in finger blood flow than shocks with the same peak magnitude but lower repetition rate (21 or 5.3 s-1) and lower rms acceleration (5 or 2.5 ms-2). Conclusions For shocks similar to those based on 125-Hz oscillations with repetition rates between 1.3 and 83.3 s-1, acute reductions in finger blood flow can be predicted from the rms acceleration.

To investigate prospectively the relation between vibration-induced sensory dysfunction and measures of daily exposure to hand-transmitted vibration (HTV). Thermal perception thresholds for warmth and cold (TPT in °C) and vibrotactile perception thresholds (VPT in dB) at 31.5 and 125 Hz were measured at the fingertips of digit II (for the median nerve) and digit V (for the ulnar nerve) of both hands in 27 male controls and 29 naval engine workers exposed to HTV. In the HTV workers, peripheral sensory function was investigated over a follow-up period of 1–3 years. Vibration exposure was expressed in terms of equivalent frequency-weighted acceleration [A h(eq,T) in ms−2 rms], duration of exposure (T in hours), and frequency-weighted acceleration normalised to a period of 8 h [A(8) in ms−2 rms]. At baseline, the HTV workers showed significantly higher TPT for warmth and lower TPT for cold than the controls, while no differences in the VPTs at both frequencies were observed between the two groups. After adjustment for several confounders, data analysis with the generalised estimating equations method and a transition model showed that the changes over time in the TPTs of the HTV workers were significantly related to all measures of daily vibration exposure [A h(eq,T), T, A(8)]. No significant associations were observed for VPTs at either 31.5 or 125 Hz. The findings of this longitudinal study suggest a significant exposure–response relationship between thermal sensory impairment over time and measures of vibration exposure. The measurement of TPT may be a useful testing method to assess vibration-induced neuropathy at an early stage.