Workplace exposure to wood dust and the prevalence of wood-specific sensitization

Comparison of high- and low-molecular-weight sensitizing agents causing occupational asthma: an evidence-based insight

INTRODUCTION

The many substances used at the workplace that can cause sensitizer-induced occupational asthma are conventionally categorized into high-molecular-weight (HMW) agents and low-molecular-weight (LMW) agents, implying implicitly that these two categories of agents are associated with distinct phenotypic profiles and pathophysiological mechanisms.

AREAS COVERED

The authors conducted an evidence-based review of available data in order to identify the similarities and differences between HMW and LMW sensitizing agents.

EXPERT OPINION

Compared with LMW agents, HMW agents are associated with a few distinct clinical features (i.e. concomitant work-related rhinitis, incidence of immediate asthmatic reactions and increase in fractional exhaled nitric oxide upon exposure) and risk factors (i.e. atopy and smoking). However, some LMW agents may exhibit 'HMW-like' phenotypic characteristics, indicating that LMW agents are a heterogeneous group of agents and that pooling them into a single group may be misleading. Regardless of the presence of detectable specific IgE antibodies, both HMW and LMW agents are associated with a mixed Th1/Th2 immune response and a predominantly eosinophilic pattern of airway inflammation. Large-scale multicenter studies are needed that use objective diagnostic criteria and assessment of airway inflammatory biomarkers to identify the pathobiological pathways involved in OA caused by the various non-protein agents.

Is micronucleus assay in nasal mucosa cells an appropriate technique for detecting genotoxins by inhalation in humans? A systematic review

This study aimed to evaluate the scientific literature on the micronucleus assay in nasal mucosa as an appropriate method for evaluating genotoxicity caused by chemical agents. According to the PRISMA guidelines, only in vivo human studies with micronucleus assays using nasal cells were considered. Reviews, case reports, editorials, letters to the editor, and articles not written in English were excluded. The following scientific databases/search engines were used: PubMed/MEDLINE, Scopus, and Web of Science. Results: This review included 13 studies. Four articles detected no statistical significance regarding the frequency of micronuclei while nine articles showed an increase in micronuclei in nasal cells. In the qualitative analysis, two articles were considered strong, eight were moderate and three were weak. The micronucleus assay using nasal mucosa cells is a sensitive and effective technique for assessing DNA damage and an appropriate method for monitoring humans continuously exposed to chemicals.

Wood dust and asthma

PURPOSE OF THE REVIEW

Review recent developments on asthma associated with wood dust, given the increasing scale of wood handling and processing activities globally.

RECENT FINDINGS

Work in wood industries is associated with a significantly increased risk of respiratory symptoms, rhinitis and asthma. This can be attributed to traditional processing techniques and newer technologies producing complex bioaerosol exposures, which may include chemicals. Meta-analysis studies indicate strong evidence for wood dusts as occupational sensitizers for asthma, but the underlying mechanisms remain poorly understood. The global prevalence of asthma in wood workers ranges between 6-18% and for rhinitis 16-33%. Exposure estimates show wide variation. Risk factors include atopy and exposure to certain wood species, elevated current and cumulative particulate exposures.

SUMMARY

Future studies should focus on better characterization of wood dust allergens and other bioaerosol components, specific immunoglobulin E responses to different wood species, pathophysiological mechanisms underlying asthma, and modelling dose-response relationships using refined exposure metrics for dust particulate and other bioaerosol components. There is a need for improved health-based international exposure standards and effective workplace control measures to reduce exposures to wood dust particulate (hard and soft woods), endotoxin and β-glucan, to reduce the risks of asthma in wood workers.

Comparison between patch test results of natural dyes and standard allergens in batik workers with occupational contact dermatitis

BACKGROUND

Occupational contact dermatitis (OCD) is a skin disorder caused by contact with any substances found in the workplace. Occupational contact dermatitis is second most common occupational disease (15% of all cases of occupational disease). Occupational contact dermatitis is divided into allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD) which is 80% of cases that affects hands. Batik is an art that is painted on cloth, it is one of Indonesian cultural heritage. Batik workers have a higher risk of obtaining OCD due to exposure to chemicals and fluids used during work. Natural dyes used in the dyeing process are less likely to cause ACD than standard allergens. Some of the natural dyes used in the dyeing process in batik industries are Indigofera tinctoria, sappan wood (Caesalpinia sappan), and Mahagony (Swietenia mahagoni) cause skin sensitisation.

OBJECTIVE

To compare the results of patch testing between natural dyes (Indigofera tinctoria, sappan wood (Caesalpinia sappan), and Mahagony (Swietenia mahagoni) with standard allergens (p-phneyldiamine 0.1%, potassium dichromate 0.5% and formaldehyde 0.1%) as a cause of ACD in batik workers in Surakarta, East Java, Indonesia.

METHOD

A cross-sectional study was conducted on 63 subjects batik workers with OCD in Surakarta, East Java, Indonesia. Subjects were patch tested with three standard allergens (p-phenylenediamine 0.1%, potassium dichromate 0.5%, and formaldehyde 1%) and natural dyes (Indigofera tinctoria, sappan wood (Caesalpinia sappan), and Mahagony (Swietenia mahagoni). A closed patch test was evaluated 48 and 96 hour later. Screening of OCD in batik workers in Surakarta, East Java, Indonesia was based on Nordic Occupational Skin Questionnaire NOSQ-2002, and diagnosis of OCD was based on Mathias criteria (at least 4 out of 7 criteria were met). Data were analysed using a non-parametric Chi-square test with SPSS 21 with a significant difference if the p-value < 0.05.

RESULT

Natural dyes significantly caused allergic contact dermatitis in batik workers in Surakarta, East Java, Indonesia than standard allergens (p = 0.016). A positive patch test was found in 11 patients, standard allergen p-phenylenediamine (PPD) 0.1% was seen on one patient, potassium dichromate 0.5% on two patients, and formaldehyde 1% on two patients. A positive patch test using Indigofera tinctoria was found at one patient, sappan wood (Caesalpinia sappan) in three patients, and Mahagony (Swietenia mahagoni) in five patients.

CONCLUSION

Natural dyes cause more positive patch test results in batik workers.

Influence of Grit Size and Wood Species on the Granularity of Dust Particles during Sanding

Wood dust poses a threat to the health of employees and the risk of explosion and fire, accelerates the wear of machines, worsens the quality of processing, and requires large financial outlays for its removal. The aim of this study was to investigate the extent to which the grit size of sandpaper influences the size of the wood dust particles and the proportion of the finest particles which, when dispersed in the air, may constitute the respirable fraction. Six species of hardwood (beech, oak, ash, hornbeam, alder, and walnut), and three species of softwood (larch, pine, and spruce) were used in the research. While sanding the samples under the established laboratory conditions, the following were measured for two types of sandpapers (grit sizes P60 and P180): mean arithmetic particle size of dust and finest dust particles content (<10 µm). Based on the obtained results, we found that the largest dust particle sizes were obtained for alder, pine, and spruce; the smallest size of dust particles during sanding with both sandpapers was obtained for beech, hornbeam, oak, ash, larch, and walnut. The mean arithmetic particle sizes ranged from 327.98 µm for pine to 104.23 µm for hornbeam. The mean particle size of the dust obtained with P60 granulation paper was 1.4 times larger than that of the dust obtained with P180 granulation sandpaper. The content of the finest dust particles ranged from 0.21% for pine (P60 sandpaper) to 12.58% for beech (P180 sandpaper).The type of wood (hardwood or softwood) has a significant influence on the particle size and the content of the finest dust fraction.

Occupational Exposure to Dust Produced when Milling Thermally Modified Wood

During production, thermally modified wood is processed using the same machining operations as unmodified wood. Machining wood is always accompanied with the creation of dust particles. The smaller they become, the more hazardous they are. Employees are exposed to a greater health hazard when machining thermally modified wood because a considerable amount of fine dust is produced under the same processing conditions than in the case of unmodified wood. The International Agency for Research on Cancer (IARC) states that wood dust causes cancer of the nasal cavity and paranasal sinuses and of the nasopharynx. Wood dust is also associated with toxic effects, irritation of the eyes, nose and throat, dermatitis, and respiratory system effects which include decreased lung capacity, chronic obstructive pulmonary disease, asthma and allergic reactions. In our research, granular composition of particles resulting from the process of longitudinal milling of heat-treated oak and spruce wood under variable conditions (i.e., the temperature of modification of 160, 180, 200 and 220 °C and feed rate of 6, 10 and 15 m.min^-1) are presented in the paper. Sieve analysis was used to determine the granular composition of particles. An increase in fine particle fraction when the temperature of modification rises was confirmed by the research. This can be due to the lower strength of thermally modified wood. Moreover, a different effect of the temperature modification on granularity due to the tree species was observed. In the case of oak wood, changes occurred at a temperature of 160 °C and in the case of spruce wood, changes occurred at the temperatures of 200 and 220 °C. At the temperatures of modification of 200 and 220 °C, the dust fraction (i.e., that occurred in the mesh sieves, particles with the size ≤ 0.08 mm) ranged from 2.99% (oak wood, feed rate of 10 m.min^-1) to 8.07% (spruce wood, feed rate of 6 m.min^-1). Such particles might have a harmful effect on employee health in wood-processing facilities.