An epidemic of silicosis among former denim sandblasters

Iron oxide particles modulate the ovalbumin-induced Th2 immune response in mice

This study was designed to investigate the modulatory effects of submicron and nanosized iron oxide (Fe(2)O(3)) particles on the ovalbumin (OVA)-induced immune Th2 response in BALB/c mice. Particles were intratracheally administered four times to mice before and during the OVA sensitization period. For each particle type, three different doses, namely 4×100, 4×250 or 4×500 μg/mouse, were used and for each dose, four groups of mice, i.e. group saline solution (1), OVA (2), particles (3), and OVA plus particles (4), were constituted. Mice exposed to OVA alone exhibited an allergic Th2-dominated response with a consistent increase in inflammatory scores, eosinophil numbers, specific IgE levels and IL-4 production. When the mice were exposed to OVA and to high and intermediate doses of iron oxide submicron- or nanoparticles, the OVA-induced allergic response was significantly inhibited, as evidenced by the decrease in eosinophil cell influx and specific IgE levels. However, the low dose (4×100 μg) of submicron particles had no significant effect on the OVA allergic response while the same dose of nanoparticles had an adjuvant effect on the Th2 response to OVA. In conclusion, these data demonstrate that the pulmonary immune response to OVA is a sensitive target for intratracheally instilled particles. Depending on the particle dose and size, the allergic response was suppressed or enhanced.

Silicosis

Silicosis is a fibrotic lung disease caused by inhalation of free crystalline silicon dioxide or silica. Occupational exposure to respirable crystalline silica dust particles occurs in many industries. Phagocytosis of crystalline silica in the lung causes lysosomal damage, activating the NALP3 inflammasome and triggering the inflammatory cascade with subsequent fibrosis. Impairment of lung function increases with disease progression, even after the patient is no longer exposed. Diagnosis of silicosis needs carefully documented records of occupational exposure and radiological features, with exclusion of other competing diagnoses. Mycobacterial diseases, airway obstruction, and lung cancer are associated with silica dust exposure. As yet, no curative treatment exists, but comprehensive management strategies help to improve quality of life and slow deterioration. Further efforts are needed for recognition and control of silica hazards, especially in developing countries.

Effect of submicron and nano-iron oxide particles on pulmonary immunity in mice

Due to advances in nanotechnology, exposure to particle compounds in the workplace has become unavoidable. Assessment of their toxicity on health is an important occupational safety issue. This study was conducted in mice to investigate the toxicological effects of submicron and nano-iron oxide particles on pulmonary immune defences. In that purpose, we explored for the first time, inflammatory and immune responses in lung-associated lymph nodes. For each particle type, mice received either a single intratracheal instillation at different concentrations (250, 375, or 500μg/mouse) or four repeated instillations at 500μg/mouse each. Cytokine production, inflammatory and innate immune response, and humoral immune response were respectively assessed 1, 2, and 6 days after particle exposures. Both types of particles induced lung inflammation associated with increased cytokine productions in lymph node cell cultures and decreased pulmonary immune responses against sheep erythrocytes. Natural killer activity was not modified by particles. In comparison to single instillation, repeated instillations resulted in a reduction of inflammatory cell numbers in both bronchoalveolar lavages and pulmonary parenchyma. Moreover, the single instillation model demonstrated that, for a same dose, nano-iron oxide particles produced higher levels of inflammation and immunodepression than their submicron-sized counterparts.

Respiratory disorders in the Middle East: a review

The spectrum of pulmonary pathology in the Middle East is as versatile as its civilizations and cultures. In this review, we outline the key challenges confronting pulmonologists in the Middle East. We shed light on the diverse conditions commonly encountered in the region, from the centuries-old illnesses of tuberculosis, to contemporary problems such as lung complications from chemical warfare. We specifically highlighted unique aspects related to respiratory illnesses in the Middle East, for example, climate factors in the desert region, cultural habits, for example, water-pipe smoking and disorders unique to the region, such as Behçet's disease. Pulmonologists are also faced with the consequences of modernization, including large immigrant population and associated social and health issues, rising incidence of obesity and sleep apnoea, and drug-resistant tuberculosis. Tackling these health issues will require an integrated approach involving public health, primary care as well as specialist pulmonology input, taking into consideration the unique cultural and environmental factors to ensure effective management and compliance to medical care.

Silicosis in denim sandblasters

BACKGROUND

During the past 2 decades, silica sand has been used widely in sandblasting denim in Turkey, which has resulted in an epidemic of silicosis. This study was conducted to summarize the clinical outcomes of formerly healthy young people who became disabled or died because of working in the textile industry.

METHODS

The medical records of patients with silicosis due to denim sandblasting who were seen at our institution between 2001 and 2009 were reviewed. Follow-up data were assessed. Compensation and vital status of patients were determined, and survival analysis was performed.

RESULTS

Thirty-two male patients diagnosed with silicosis due to denim sandblasting over an 8-year period were identified. Mean age was 31.5 years. They worked as denim sandblasters for a mean 66.4 h/wk for a median 28.5 months. Their mean cumulative exposure time to silica sand was 12,957 h. The median follow-up period was 29 months (range 3-101 months). The median latency period (time elapsed between initial exposure and diagnosis) was 5.5 years (range 2-14 years). Six of the followed patients (19%) died of progressive massive fibrosis. Nine of the patients (28%) were compensated because of silicosis. Just two patients with silicosis received compensation before they died. The mean survival rate was 78 months. The estimated 5-year survival rate was 69% for denim sandblasters with silicosis.

CONCLUSIONS

Silicosis in young individuals after exposure in the textile sector suggests a lack of awareness of the hazards of silica outside of the traditional occupations associated with silicosis. Death from silicosis in young people suggests overexposure and unsafe working conditions as a result of a lack of control.

MDCT findings of denim-sandblasting-induced silicosis: a cross-sectional study

BACKGROUND

Denim sandblasting is as a novel cause of silicosis in Turkey, with reports of a recent increase in cases and fatal outcomes. We aimed to describe the radiological features of patients exposed to silica during denim sandblasting and define factors related to the development of silicosis.

METHODS

Sixty consecutive men with a history of exposure to silica during denim sandblasting were recruited. All CT examinations were performed using a 64-row multi-detector CT (MDCT). The nodules were qualitatively and semi-quantitatively analyzed by grading nodular profusion (NP) on CT images.

RESULTS

Silicosis was diagnosed radiologically in 73.3% of patients (44 of 60). The latency period (the time between initial exposure and radiological imaging) and duration of silica exposure was longer in patients diagnosed with silicosis than in those without silicosis (p < 0.05). Nodules were present in all cases with centrilobular type as the commonest (63.6%). All cases of silicosis were clinically classified as accelerated and 11.4% had progressive massive fibrosis (PMF). Mild NP lesions were the most prevalent in all six zones of the lung. The NP score was significantly correlated with the duration of silica exposure, the latency period, presence of PMF, and pleural thickening. Enlarged lymphadenopathy was present in 45.5% of patients.

CONCLUSIONS

The duration of exposure and the latency period are important for development of silicosis in denim sandblasters. MDCT is a useful tool in detecting findings of silicosis in workers who has silica exposure.