Occupational bronchial asthma caused by exposure to polyvinyl chloride: phenotypes of the disease

Abstract

Introduction.Mechanism underlying development of occupational bronchial asthma (OA) caused by exposure to polyvinyl chloride (PVC) aerosols is not completely clear. Complex properties of PVC aerosols components indicate possible development of OA among workers via both non-immune and immune mechanisms.Objectiveis to study clinical and genetic characteristics of occupational bronchial asthma development at meat packers’ workplace.Materials and methods.Examination covered 113 male and female meat-processing plant workers. A group (48 people) appeared to have daily contact with toxic-allergenic aerosols which were released as a smoke into the working area from molten PVC membrane during the meat products packing. All the examinees underwent clinical and functional tests of bronchopulmonary system and molecular genetic studies: identification of hyposecretory alleles of α–1IP gene; determination of genetic polymorphism of GSTM1 and GSTT 1.Results and discussion.The study proved that exposure to PVC degradation products causes irritation and sensitization of the respiratory tract, visible mucous membranes and skin. The examinees with 5–10 years of service demonstrated reversible obstructive pulmonary ventilation disorders with bronchial hypersensitivity to occupational factors (30 people) and symptoms of bronchial asthma (18 people) of immune and non-immune origin. The asthma phenotypes were determined: occupational — immune and non-immune (11 people) and aggravated by work conditions (7 people). The study proved that individual risk factors of occupational bronchial asthma in meat-packers are: hyposecretory PiMZ variant of α1-PI gene and deletion of glutathione-S-transferase genes (GSTM1 and GSTT 1). The findings prove that meatpackers’ asthma is a multifactorial disease.Conclusion.Hyposecretory alleles of α1-PI gene appeared to participate in occupational bronchial asthma development. Identified relationships between hyposecretory variants of α1-PI gene, null alleles of glutathione-S-transferase genes (GSTM1 and GSTT 1) carriage, occupational bronchial asthma development and severity suggest that meat-packers’ asthma is a multifactorial disease. This could be an explanation of various phenotypes of occupational bronchial asthma. Problem of occupational bronchial asthma development due to influence of PVC pyrolysis products necessitates further wide clinical, hygienic and molecular genetic studies.