Pulmonary injury associated with spray of a water-based nano-sized waterproofing product: a case study

Background

In most reported cases of lung trauma with water proofing products, volatile organic compounds (VOC) have a prominent role. Here we report on a case involving ten workers exposed to a sprayed product containing nanoparticles in a water solution with only a few percent VOC.

Case presentation

Ten workers suffered from respiratory symptoms following spray impregnation of hardwood furniture using a waterproofing product that contained positively charged fluorinated acrylate copolymer solid cores with a median diameter of 70 nm (1.3 w%) in aqueous suspension with 3.3 w% VOC and 0.3 w% quaternary ammonium. The worker who applied one liter of the product in a wood workshop, using an air mix spray gun, did not report any health complaints. Another worker, who entered the workshop 3 h later and had rolled and smoked two cigarettes, was hospitalized with severe chemical pneumonitis. A chest X-ray (CXR) showed bilateral infiltrative impairment in the lower lobe regions. On the next day a second CXR showed increased patchiness marking in all fields. A high-resolution Computer Tomography (CT)-scan demonstrated extensive bilateral areas of ground-glass opacities predominantly in the lower regions of the upper lobes, the right middle lobe and the apical regions of the lower lobes, compatible with severe chemical pneumonitis. On the following morning, nine workers in an adjacent workplace in the same building, experienced dry cough, chest tightness and substernal pain upon physical exercise. Reconstruction of the spray application in a climate chamber confirmed trimethyl silanol, glycol ethers and fluoroalkenes in the gas phase. Immediately after the spray application, aerosols were observed at a maximum concentration of 6.3 × 10⁴ cm⁻³. Mass concentrations were 0.095 and 10 mg/m³ in the size ranges 5.6-560 nm and 0.22-30 μm, respectively, decreasing to less than 10 μg/m³ in both size ranges after 15 h.

Conclusion

The hospitalized worker had smoked cigarettes contaminated with fluoropolymers which is a plausible explanation for the lung trauma. Respiratory symptoms in the nine workers may be caused by inhalation of particles that became airborne by resuspension from surfaces when workers entered the adjacent workplace the next day. A contribution from VOC appears less likely because measurements and modelling showed that concentrations in the mg/m³ range could have occurred only if the building was assumed to be completely airtight.

Electronic supplementary material

The online version of this article (10.1186/s12995-017-0180-7) contains supplementary material, which is available to authorized users.

Bronchiolitis Obliterans Syndrome in Chemical Workers Producing Diacetyl for Food Flavorings

RATIONALE

Workers in microwave popcorn plants are at risk of developing bronchiolitis obliterans associated with exposure to butter flavoring volatiles, including diacetyl.

OBJECTIVES

To investigate the risk of bronchiolitis obliterans for chemical workers producing diacetyl, with exposure to less complex mixtures of chemicals.

METHODS

We interviewed and conducted spirometry on 175 of 196 workers from a chemical production plant that produced diacetyl between 1960 and 2003. We used all available historical exposure data to classify all workers into three exposure groups with varying exposure profiles to diacetyl, based on frequency and level of exposure.

MEASUREMENTS AND MAIN RESULTS

Workers with fixed airway obstruction underwent further pulmonary function testing (including diffusing capacity and lung volumes) and paired inspiratory and expiratory high-resolution computed tomography studies. We identified three cases consistent with bronchiolitis obliterans syndrome with air trapping on high-resolution computed tomography of the lungs, in the highest exposure group of 102 process operators. Two of these cases were lifelong nonsmokers. Potential exposures included acetoin, diacetyl, acetaldehyde, and acetic acid, with diacetyl exposures in the range previously reported to be associated with fixed airway obstruction in the microwave popcorn industry.

CONCLUSIONS

Exposure to an agent during diacetyl production appears to be responsible for causing bronchiolitis obliterans syndrome in chemical process operators, consistent with the suspected role of diacetyl in downstream food production.