*3.3. Simulation of a Short-Term Exposure Scenario: Estimation of Room Reference Concentrations (Ci,ref) and Health-Related Evaluation*

Once the emission rates for 'heating mode' were estimated, indoor concentrations potentially determined by each single bag under actual conditions of use were derived (Table 4). The exposure scenario taken into account is representative of a short-term inhalation exposure related to the use of the heating bag during the first period of its life-cycle. Moreover, the exposure scenario considers only one bag under heating in a 30 m<sup>3</sup> room resulting in VOC emissions, promoted by high temperature, diluted in the entire volume of the room. For this reason, in the present work, the estimated room reference concentration values that room occupants could be exposed to are low for all the three investigated bags, ranging overall, with the only exception of naphthalene, from 0.01 μg/m3 (benzene for 'polyester-brand A'; benzene, chlorobenzene, and 1,3,5-trimethylbenzene for 'PVC-brand B'; 1,2-dichloroethane for 'PVC-brand C') to 0.48 μg/m3 (1,2,4,-trimethylbenzene for 'polyester-brand A'). Attention has to be paid, instead, to the potential inhalation exposure to naphthalene occurring when the polyester bag

is used, according to the selected scenario. On the basis of the obtained results, it may be predicted that, as a consequence of the heating process, the naphthalene indoor concentration determined by the polyester bag in a real setting would be equal to about 42 μg/m3. This evidence is worthy of further discussion as human exposure to naphthalene has been recognized as a public health concern due to demonstrated harmful effects [30]. Naphthalene is indeed classified as a possible human carcinogen (group 2B) by the International Agency for Research on Cancer (IARC) and is included in EU category Carc.2 on the basis of experimental evidence in animals regarding an increased risk of contracting respiratory tract cancer [31,32]. Health-based evaluation of VOC emissions from materials is generally based on the comparison of room reference concentrations for individual compounds with guideline values. In order to assess the potential risks to health arising from inhalation exposure to individual VOCs, most of the existing health-related evaluation schemes at European level are based on the LCI (Lowest Concentration of Interest) approach. The proposed EU-LCI values are health-based reference concentrations for inhalation exposure intended as 'safe' levels where no health impairment is expected, even with a life-long exposure. EU-LCI levels, however, are usually compared to indoor concentrations representative of long-term exposure and based on emission rates derived after 28 days of chamber testing. This basic assumption would apparently limit our discussion, not allowing us to highlight if potential health risks for inhalation exposure could occur in the case of 'polyester-brand A' heating bag use. Therefore, in this regard, clarification is needed. Taking into account the most comprehensive evaluation scheme at EU level, the German AgBB scheme 'Evaluation procedure for VOC emissions from building products', chemicals with potential carcinogenic effects belonging to EU category Carc.2 are also eligible to be checked within the LCI concept at the first step of the evaluation scheme, related to 3-day chamber testing [27]. The room reference concentration estimated for naphthalene (42 μg/m3), therefore, is eligible to be compared with the LCI value equal to 10 μg/m3. From the comparison, it is possible to state that the actual use of the 'polyester-brand A' heating bag in the first period of its life-cycle could determine a naphthalene concentration inside a 30 m3 room eight times higher than the reference LCI value. The inhalation exposure to naphthalene emission could represent, therefore, a risk for end users and room occupants. It is also important to point out that the item under investigation is intended to be used very close to the human upper airways, and the resulting exposure may be exacerbated. Moreover, the ventilation inside a real setting may be reduced with respect to the 'ideal' conditions (e.g., 0.5 h−<sup>1</sup> air exchange rate), leading to higher VOC concentrations in the air volume in proximity with the item, and therefore close to the breathing zone, compared with the rest of the room [33]. Finally, although the most remarkable result has to be attributed to the naphthalene emission from the 'polyester-brand A' bag, it should be noted that both 'polyester-brand A' and 'PVC-brand B' released benzene, recognized as a carcinogen in humans for which no safe level of inhalation exposure can be recommended. In this regard, the World Health Organization pronounced a suggestion to reduce or eliminate the use of materials that are able to release benzene [30].


**Table 4.** Simulation of a short-term exposure scenario: estimation of room reference concentrations (Ci,ref, μg/m3) determined by bags on 'heating mode'.
