Original articleParkinson's disease and solvents: Is there a causal link?
Introduction
The putative causal role of certain chemicals in disorders mimicking Parkinson's disease (PD) is based on data drawn from accidental, deliberate and occupational contamination, epidemiological studies, controlled animal studies and mechanistic investigations [1], [2], [3]. Whether prolonged exposures to individual or combinations of organic solvents result in PD remains unresolved. Nevertheless, many organic solvents have acute and chronic neurotoxic potential [4], [5], [6]. The spectrum of chronic neurological impairment in cases subjected to prolonged, repeated exposure to organic solvents is wide. The peripheral nervous system [7] as well as the central nervous system can both be targeted. Prolonged workplace exposure to organic solvents can induce a chronic solvent encephalopathy (CSE) that persists even after the exposure is terminated [8]. Organic solvent neurotoxicity can also impact the sense of smell [9], [10], sleep [10], eyesight [11] and hearing, and some solvents have a synergistic effect with noise and so induce hearing loss [12].
In the present report, we discuss three PD cases in car painters with occupational exposures to organic solvents in different workplace settings.
Section snippets
Patients and methods
The three patients had been examined and followed-up by trained neurologists at their private offices. All three had been referred to senior neurologists at PD expert centers (in Poitiers, Paris and Strasbourg), and two of them (Patients A and B) had then been further referred for consultation at the occupational medicine departments of teaching hospitals. The patients were also examined clinically and by brain dopamine transporter (DAT) single-photon emission computed tomography (SPECT), using
Results
All three patients were professional car painters (Table 1). Their jobs required the use of solvent-containing paints, thinners, glues, lacquers, adhesives and surface cleaners. Workplace products reportedly contained trichloroethylene (TCE), toluene, xylene and styrene. Only two of the patients (C and A, the latter only occasionally) used masks as personal protective equipment, and only Patient C worked in a ventilated workplace.
The patients’ personal histories revealed no regular or excessive
Discussion
With the notable exception of occupational exposures to the solvent carbon disulphide – widely used in the viscose rayon industry in France and elsewhere during the last century – with which parkinsonism has been strongly associated [16], [17], clinical reports of parkinsonism associated with chronic occupational chemical exposures are rare. The recent literature offers published cases for TCE [18], [19], [20], n-hexane [21], [22] and mixed organic solvents in cases of painters [23]. Our
Conclusion
Large-scale investigations are needed to determine whether or not chronic exposures to specific organic solvents or mixtures are associated with PD. We suggest that these be epidemiological studies in occupational settings that routinely use organic solvents (such as industrial painters). Detailed surveillance of specific chemicals in the workplace, together with assessment of personal exposures (via inhalation and skin), should be carried out longitudinally.
The question of a link between
Disclosure of interest
The authors declare that they have no competing interest.
Acknowledgments
The authors wish to thank the Solvaquest group from the Occupational health service (ASSTV86, Vienne, Poitiers, France) for patient recruitment, and neurologist Professor J.L. Houeto for these patients’ care in the neuropsychology department of the CHU of Poitiers (France). The authors also thank Dr J.M. Reiser (SNCF, Paris), Dr N. Seiller (Sarreguemines), Dr A. Anguenot (La Rochelle), Dr N. Ayrivié (La Rochelle), Dr G. Lacroix (Rochefort), Dr Prof. C. Tranchant (Strasbourg) and Dr Prof
References (34)
- et al.
Parkinson's disease: is there a strong environmental contribution?
Rev Neurol
(2010) - et al.
Industrial toxicants and Parkinson's disease
Neurotoxicology
(2012) - et al.
The course of chronic solvent induced encephalopathy: a systematic review
Neurotoxicology
(2009) - et al.
Sleep disturbances and occupational exposure to solvents
Sleep Med Rev
(2009) - et al.
An international questionnaire to explore neurotoxic symptoms
Environ Res
(1997) - et al.
Evaluation of the French version of EUROQUEST: a questionnaire for neurotoxic symptoms
Neurotoxicology
(2003) - et al.
Parkinsonism due to n-hexane exposure
Lancet
(1989) - et al.
Dopamine transporter binding study in differentiating carbon disulfide induced parkinsonism from idiopathic parkinsonism
Neurotoxicology
(2004) - et al.
Solvents and Parkinson disease: a systematic review of toxicological and epidemiological evidence
Toxicol Appl Pharmacol
(2013) Environmental toxins and Parkinson's disease
Annu Rev Pharmacol Toxicol
(2014)