Aromatic solvents and volatile organic compounds: what still needs to be done after 40 years of preventive interventions

A. Moretto | Department of Cardio-Thoracic-Vascular Sciences and Public Health, University of Padua; Occupational Medicine Unit, Padua University Hospital, Italy

Introduction. Over 40 years after the introduction of the first mitigation regulations and strategies, managing exposure to aromatic solvents and volatile organic compounds (VOCs) still presents a challenge in the field of environmental and occupational prevention. Aromatic solvents – particularly benzene, toluene, ethylbenzene, and xylenes (BTEX) – are substances widely used in industrial processes due to their physicochemical properties. These substances are associated with short- and long-term toxic effects, including, in the case of benzene, an increased incidence of leukemia. VOCs also contribute to the formation of tropospheric ozone and photochemical smog, with a resulting impact on public health.

Objectives. The evaluation of the effectiveness of the preventive actions adopted over the years, including the definition of occupational exposure limits, with the aim of progressively reducing total emissions and partially replacing substances. Identification of actions to be taken.

Methods. Literature analysis for the toxicological characterization of the main VOCs, particularly BTEX, and subsequent derivation of exposure limits. Analysis of the effects on exposed workers. Analysis of monitoring techniques, particularly for complex mixtures. Analysis of regulations and adopted limits.

Results and Conclusions. In the past, especially in Scandinavian countries, chronic effects of organic solvents on the central nervous system were reported. These effects had been attributed to the lipophilic properties of the solvents and were defined as “psycho-organic syndrome”, with symptoms including irritability, mood reduction, and anxiety, often summarized as “nervousness” and occasionally accompanied by peripheral nerve symptoms. The actual existence of this syndrome has often been questioned. In any case, the reporting of these cases has greatly decreased, likely also in relation to the reduction in exposure levels. According to paragraph 11, article 268 of Legislative Decree 152/2006, VOCs are defined as any organic compound that has a vapor pressure of 0.01 kPa or higher at 293.15 K (20°C). This definition of VOCs includes compounds that, in addition to the similar physicochemical characteristic of volatility and lipophilicity, exhibit different toxicological characteristics, both qualitatively (different effects) and quantitatively (different potency in causing the same effect). In the near future, priorities will need to include: updating the limit thresholds based on the latest evidence, extending preventive measures to indoor and semi-confined environments, and a better understanding of the effects related to exposure to mixtures. In particular, exposure measurements should assess the reliability and level of uncertainty associated with the determination of a portion of the compounds, considered as tracers of total exposure. For this, it will be necessary to better understand the emission sources and their characteristics, taking into account the technological evolution that could lead to the introduction of new, less studied compounds.