An exposure-based framework for grouping pollutants for a cumulative risk assessment approach: Case study of indoor semi-volatile organic compounds

Abstract

Humans are exposed to a large number of contaminants, many of which may have similar health effects. This paper presents a framework for identifying pollutants to be included in a cumulative risk assessment approach. To account for the possibility of simultaneous exposure to chemicals with common toxic modes of action, the first step of the traditional risk assessment process, i.e. hazard identification, is structured in three sub-steps: (1a) Identification of pollutants people are exposed to, (1b) identification of effects and mechanisms of action of these pollutants, (1c) grouping of pollutants according to similarity of their mechanism of action and health effects. Based on this exposure-based grouping we can derive "multi-pollutant" toxicity reference values, in the "dose-response assessment" step. The approach proposed in this work is original in that it is based on real exposures instead of a limited number of pollutants from a unique chemical family, as traditionally performed. This framework is illustrated by the case study of semi-volatile organic compounds in French dwellings, providing insights into practical considerations regarding the accuracy of the available toxicological information. This case study illustrates the value of the exposure-based approach as opposed to the traditional cumulative framework, in which chemicals with similar health effects were not always included in the same chemical class.

Sources and dynamics of semivolatile organic compounds in a single‐family residence in northern California

“…Among the potentially important routes of exposure are inhalation of gases and airborne particles, ingestion of dust, and permeation of the skin following direct physical contact with surfaces or partitioning into skin oils from air . Certain SVOCs are linked with negative human health outcomes, such as reprotoxic and neurotoxic effects, thus motivating national and international control efforts . However, owing to their persistent nature, including wide distribution on indoor surfaces, occupant exposures to SVOCs may occur long after eliminating the original sources .…”

“…3,10,11 Certain SVOCs are linked with negative human health outcomes, such as reprotoxic and neurotoxic effects, thus motivating national and international control efforts. 9,[12][13][14][15][16] However, owing to their persistent nature, including wide distribution on indoor surfaces, occupant exposures to SVOCs may occur long after eliminating the original sources. 9 For this reason, SVOCs that have not been routinely used indoors for many years may continue to exhibit measurable levels in air, in dust, and in body fluids.…”

Relative toxicity for indoor semi volatile organic compounds based on neuronal death

“…SVOCs were included in the present work when they were detected in more than 10% of the dwellings investigated (from 30 to 285, according to the campaign). SVOC grouping was based on an approach previously described (Fournier et al 2014a). For each chemical, an initial hazard identification was performed by means of a literature review covering its neurotoxic effects in humans and other mammals.…”

“…As well as being of high enough quality to be taken into consideration, studies should describe at least one adverse effect on the neurological system, regardless of the experimental system used. SVOCs were then grouped by common key events, when known (Fournier et al 2014a). An update of this work enabled selection of a group of SVOCs based on neuronal death as a common endpoint, taking into consideration the potential relationship between neuronal death and disturbance to neurobehavioral abilities (Sharma et al 2009;Lahouel et al 2016;Grova et al 2007;Dominico et al 2002;Bouayed et al 2009;Rammal et al 2010).…”

“…This outcome was caused by different upstream key events leading to membrane alteration (for 11 SVOCs), mitochondrial impairment (for 17 SVOCs) or neurotransmitter modulation (for 7 SVOCs), as shown in Figure 2. Neuronal death is the endpoint that includes the highest number of SVOCs (Fournier et al 2014a) with exploitable dose/ concentration-response data, and is thus retained for the derivation of BMCs. For example, only 11 chemicals have at least 3 dose groups based on in vivo neurobehavioral changes with different responses measured (i.e.…”