Políticas de prevenção e seus efeitos sobre a exposição ocupacional ao Benzeno.

Abstract

Context - Benzene has been recognized worldwide as a carcinogen to humans since 1982. This launched the proposal and implementation of prevention policies based on the Conventions established by the International Labor Organization. Brazil produces and uses benzene widely in many different industrial processes resulting in many potentially exposed workers. In 1995, Regulatory Standard 15, 13a, of the Ministry of Labor, MT, established a mandatory implementation of the Programs for the Prevention of Occupational Exposure to Benzene (PPEOB). Later, MT defined the measurement of trans-muconic acid (ttMA) as a biomarker of benzene exposure. After 25 years, the effects of this Policy on occupational exposure to this agent are still unknown. Objective – to describe the impact of the prevention policies on benzene occupational exposure, in the world and, in Brazil. Specific objectives – 1) Study 1: to systematize the knowledge about the impact of prevention policies on benzene exposure in the world; 2) Study 2- in Brazil, to investigate the adoption of NR15, through the degree of implementation of the PPEOB according to components, dimensions and subdimensions, in some companies in Brazil; 3) Study 3- to the PPEOB effects on occupational exposure to benzene, analyzed by a biomarker - trans-muconic acid. Methods – Study 1: A systematic review of observational studies and literature reviews was carried out from the year 2000 to 2020 in Web of Science, PUBMED, VHL, SCIELO, LILACS, EMBASE. Study 2. This is a pre-post study carried out with documents and databases for the years 2000 and 2017 in benzene users’ companies. Data correspond to records obtained from a checklist developed by a a Tripartite Commission, utilized by labor inspectors of the Ministry of Labor (MT). The workplace inspections were carried out by inspectors and e accompanied by GTB members, and technicians from the companies. They were aimed to evaluate the implementation of prevention and control programs according to dimensions, subdimensions and component variables. Each variable answer was coded with 0 = not implemented,1= partially implemented or 2 = fully implemented, Composite scores were estimated corresponding to the unweighted sum of variables codes. The proportion of these scores in relation to the maximum achievable measure the implementation degree. Pre-post differences correspond to the proportionate percentage change over time (PPV%) of the degree of implementation. Study 3. The design is a cross-sectional study conducted with PPEOB documents and databases sent to the MT by inspected companies at six months interval from 2012 to 2017. All companies inspected by the MT from one (N=9) with available data were studied. Exposed to benzene were workers with measurements of trans-muconic acid greater than or equal to 0.5 mg/g of creatinine. Findings: Study 1. Twenty-five articles were selected that focused on European and North American countries. Average concentrations of benzene in the air declined from the mid-1980s to the end of the study period. In China and Korea, the decline had fluctuations. There were differences in trends according to occupation and companies even if they were in the same activity. Factors associated with the decline were: reduction in allowed limits of occupational exposure, regulatory changes, and the adoption of technological innovations. Study 2. Out of the nine companies four showed an increase in the implementation of the PPEOB, most commonly with the adoption of Technological Solutions for Collective Protection; three presented variable evolution (positive, negative, and stationary), according to the subdimensions and two presented some subdimensions with negative evolution and scope as well as quality of monitoring of benzene exposure. Study 3- Out of the 1,058 workers with IBE measures between 2012 and 2017, exposed workers were identified in 2012 in each of the companies that had data collected, which turned to only one company in the last year of the study (2017). Consistently, the highest proportion of exposed occurred in those with negative parameters of implementation of the PPEOB. Conclusion: Study 1- Scientific evidence shows a decline in levels of benzene concentrations in occupational environments, with differences among countries, companies, and occupations. Study 2 - Despite the small number and limited scope of the companies, these findings show advances in the degree of implementation of measures to control benzene exposure in almost half of the companies, although despite of the workspace inspections, 1/3 did not advance significantly. Although the inspections were carried out on a biennial basis, the process of implementing control measures, particularly technological solutions, occurs in the medium or long term. For this reason, in Study 2, we chose to use the data of the first audit performed after the new regulation of benzene, and the last one with an interval of 17 years between the pre and post measures. This large interval limits the conclusions/inferences of this study, Study 3 - Considering methodological limitations, this study furthers advances knowledge about occupational exposure to benzene in Brazilian companies. Brazilian studies are scarce, and results are based on prior regulatory standards. So, this study brings new evidence on the levels of exposure to benzene that workers in different occupations and companies are subjected. This information can be valuable to support discussions on improvements in the policy of preventing benzene exposure in the country. However, in general, the conclusions of study 2 and 3 present limitations due to: 1 ) the data comes from the database of the MT and the companies, for which the author was granted access; 2)the data of IBE measurements, used in Article 3, was collected by the companies with respect to a legal requirement, 3)the sample was not probabilistic or representative, nor guided by the required statistical power of the study to allow population inferences even if it were for each company separately; 4)the data available for study 3 are sparse with long intervals without records and focusing on some repeated measures making it difficult to analyze the measures of a continuous nature; Despite the limitations, the results showed that, although with a positive evolution with respect to the implementation of a prevention policy in almost half of the evaluated companies, situations of exposure to benzene still persist in all companies included in this study. These results are significant, especially since it is the first quantitative analysis after the regulatory framework for the prevention of occupational exposure to benzene.