Reply to ‘Letter to the Editor: “Asbestosis Requiring Lung Transplantation in a Retired Hairdresser: An Occupational Exposure to Comb Through”’

We thank the letter writers for their thoughtful comments on our case report, ‘Asbestosis Requiring Lung Transplantation in a Retired Hairdresser: An Occupational Exposure to Comb Through’ [1]. We appreciate the opportunity to clarify several points and to underscore the intended scope of our report. First, we strongly agree that case reports are hypothesis-generating and not designed to establish causality. Our intent was not to broadly classify hairdressers as a high-risk occupational group, but rather to highlight an unusual case of asbestosis in a patient without known conventional exposures and to suggest that historical occupational risks in non-traditional settings should be considered when evaluating fibrotic lung disease. Second, we acknowledge that airborne asbestos exposures from hairdryers reported in structures per cubic centimetre (s/cc) fall well below the levels associated with clinical disease. The writers correctly identify that this clinical exposure threshold is 25–100 fibre/mL-years as opposed to the stated 25,100 fibres/cc per year and we will ensure to have this corrected. Laboratory studies, however, may underestimate real-world conditions. Our patient described working in a small, poorly ventilated salon where multiple hairdryers operated simultaneously. In the original 1979 NIOSH study, hairdryers were tested individually in a clean air chamber with HEPA filters [2]. In practice, released asbestos fibres could be re-entrained into the appliance, increasing potential for dose exposure. Prolonged use of the hairdryer, which our patient used consistently for over a decade, could also lead to degradation of insulation over time and increase emissions—raising exposures beyond those seen in controlled studies. Third, histopathology of the explanted lungs showed multiple asbestos bodies and lower lobe–predominant diffuse interstitial fibrosis, strongly supporting a diagnosis of asbestosis. While fibre quantification and typing would have been valuable, these analyses are unavailable in our lab and residual explant tissue has since been disposed of as per protocol. The presence of bilateral calcified pleural plaques is also of relevance; prior literature shows that in regions not endemic for plaques, 80%–90% of well-defined plaques are attributable to occupational asbestos exposure [3]. Fourth, regarding cosmetic talc, we agree exposures are typically low and epidemiologic studies have not shown increased mesothelioma risk among hairdressers [4]. The development of asbestosis generally requires higher chronic exposures than mesothelioma, suggesting talc was an unlikely contributor. Nonetheless, because we could not distinguish exposures by history or pathology, we included this information for completeness and will clarify its relative importance. As this is the first reported case of asbestosis in a hairdresser, we emphasise the need for caution when attributing causality to his occupational exposures as unrecognised asbestos exposures may have contributed to this patient's disease. We reiterate that this case highlights the importance of eliciting a comprehensive occupational history, particularly in patients with fibrotic lung disease of unclear aetiology. Even in occupations not traditionally considered high risk, historic exposures may still have clinical relevance given the long latency of asbestos-related disease. We are grateful for the correspondence and hope this exchange stimulates further consideration of atypical occupational exposures in the assessment of interstitial lung disease. Alim Hirji drafted the letter. Lakshmi Puttagunta reviewed and edited the letter. Ruojin Bu reviewed and edited the letter. All other authors of the original case report also reviewed the letter and provided feedback. The authors received no specific funding for this work. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request.

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