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Total health assessment of chemicals in indoor climate from various consumer products 7 Discussion, conclusions and recommendations7.1 Discussion and conclusions7.1.1 Assumptions in model calculationsPotential indoor concentrations of 8 selected volatile chemicals have been estimated based on pragmatic model calculations with some assumptions and simplifications. This is necessary, because the available data in the DEPA reports have different character and aim, and not necessarily produced with the purpose assessing indoor climate. Further, the determinations of the released chemicals were not always specific and reliable, since screening methods were applied. These have served the purpose of the particular report but if the aim from the start had been to look at the importance of indoor concentrations other procedures may have been selected. It has implicit been presumed that the studied consumer products were representative, adequate and relevant for indoor climate. However, data suggests a large variation within certain product groups. Thus the measured emissions may not be typical for all investigated products, especially if only one product was studied. The products are more likely indicators for the emission from the investigated product type. The background for model calculations based on the DEPA consumer product reports has been that these reports represent the potential most important sources of pollution indoor from consumer products. It should, however, be emphasized that in practice there may exist other important and unpredictable sources than the studied. It is not possible to predict human behavior at home. Situations may develop, where consumer products are used indoors, although others are recommended. Certain times of the year, e.g. at Christmas time, some activities differ from what is normal the rest of the year. In the dark time the use of candle lights increases, and in the cold time many dwellings will have less ventilation because of a wish to save energy. Building technology may also have influence on the healthy conditions in a home, e.g. if water damage occurs and mould grows. Indoor air quality depends on ventilation, temperature and other factors, besides the pollution sources being present. In this report the focus is on the contribution from consumer products but it has to be kept in mind that there may be other sources of the same chemicals in the home, e.g. from tobacco smoking, food preparation and evaporations from building materials (paint and varnishes, integrated carpets etc.). There are a great number of potential sources. The concentration (exposure) of pollutants in indoor air depends mainly on the balance between the pollution sources, and how much clean air is supplied to the building (ventilation) to dilute the pollution. Further, the concentration depends on how much pollution is deposited on surfaces (adsorption) or released from surfaces (desorption). In addition, the concentration and composition depend on any secondary chemical reaction occurring in the air or at contact with material surfaces. In the reports from the DEPA and in this report the importance of such reactions is not taken into account. Where the focus earlier was solely on the so-called primary evaporation of chemicals from materials, the research focus is nowadays directed at the secondary evaporation. Primary evaporation is release of weakly bound substances, e.g. volatile organic compounds (VOC), used or formed in connection with the manufacture and the material or substances. The primary evaporation occurs mainly, when the material is new. Secondary evaporation consists of VOC formed after the manufacture of the material. The origin may be degradation processes at oxidation of the material surface by ozone. Newly research has shown that secondary evaporation particularly can diminish the quality of indoor air and in this way have adverse health effects on building users. [18] For some materials this type of evaporation seems to continue in the whole lifetime of the materials. [19] In spite of these reservations regards the performed model calculations, it is concluded that for the eight selected volatile compounds, the highest concentrations in a home are likely to occur in the children’s room. The reason is that this particular room normally is smaller than most other rooms in the home, and it contains many products, which may release chemicals to the air. There is a clear tendency that new products release more chemicals to the air than older used products. The products also differ from each other by having different emission patterns. Some release substances over long time, others have a more extreme and brief character. Use of incense and spray products indoors are the most polluting of the studied products/activities and emit considerable amounts of hazardous chemicals. 7.1.2 Assessment of prioritized chemicalsThe maximal exposure to phenol from all sources is calculated to 62 µg/m³. This concentration is much lower than an indoor limit value of 400 µg/m³ based on odor nuisance. The calculated daily intake for a maximum exposed child is then 90 µg phenol/kg, or somewhat below the USEPA Reference Dose (RfD) of 0.1 mg/kg bw/d, which has built-in safety factors. This shows that in a children’s room, where a single pollution source may not be important, the total burden to phenol from all sources in the worst case may approach the highest tolerable for children. Normally, formaldehyde levels in indoor air are estimated to 0.01-0.20 mg/m³, depending on which sources exist. In this project the calculated maximum concentration of formaldehyde in indoor air was about 500 µg/m³, however, typically the concentration will be below 50 µg/m³. Thus, the recommended indoor air limit value for formaldehyde of 0.12 mg/m³ is complied with at the typical concentration but not in the worst, however unlikely, case. A child will typically daily inhale 72 µg formaldehyde/kg bw but 0.7 mg/kg bw in the worst case. Thus, the Reference Dose of 0.2 mg/kg bw/d will be easily complied with for a child in the typical case but not in the worst case adding up all sources working simultaneously. Formaldehyde is a potent carcinogen, and since there is no complete safe limit for carcinogens, all unnecessary exposure to formaldehyde, e.g. from incense, should be avoided. The worst case total exposure to acetaldehyde from many sources will be 265 µg/m³ - but normally lower than 10 µg/m³; thus close to the USEPA Reference Concentration (RfC) of 9 µg/m³. This RfC is based on the no-adverse-effect-level (NOAEL) in animal studies and with a safe factor of 1000 applied. Since acetaldehyde is a carcinogen, and there is no complete safe limit for carcinogens, all unnecessary exposure to acetaldehyde, e.g. from incense, should be avoided The contribution of benzene to the indoor climate from the few products investigated in the DEPA reports is <1 µg/m³. This is less than the typical benzene concentrations measured indoors in Danish buildings. During use of incense extreme benzene concentrations up to 350 µg/m3 may develop. The Reference concentration for benzene is reported to 9-30 µg/m³, and an increased cancer risk is possible at concentrations over 20 µg/m³. For plasticine alone the safety factor is sufficient but that is not the case regards a total assessment. Furthermore, use of incense generates short-term benzene concentrations of 350 µg/m³, which are a direct health hazard. The Reference Dose for benzene is 4 µg/kg bw/d. Normally, a child will inhale <1 µg benzene/kg bw during 24 hours, however, during use of incense alone the intake during one hours exposure accounts up to 21 µg benzene/kg bw/d. Such high exposure is completely unacceptable regards a substance proved to induce leukemia in humans. The highest calculated concentrations of toluene were found in the children’s room with a concentration of about 49 µg/m³ for new electronic products and about 19 µg/m³ for used products. The contribution mainly came from one particular PC monitor. To this should be added potential contributions from other consumer products of up to 900 µg/m³; however, totally about 2,980 µg/m³ with printed matters and 39,000 µg/m³ from spray paint. The Reference Dose for toluene is 223 µg/kg bw/d, and the Reference Concentration is 0.4 mg/m³. An indoor climate limit for toluene of 8 mg/m³ has been suggested. With a toluene concentration of 50 µg/m³ emitted from a monitor working 6 hours a day a child will have a daily intake of 12 µg/kg bw/d, thus sufficient safety margin. However, this is certainly not the case, if the contributions from other sources are added on. Even without contributions from printed matters spray paint the intake of 1,800 µg/d or 180 µg/kg bw/d is very close to the highest tolerable. The highest concentrations of xylenes occur also in the children’s room, where the concentration is 105 µg/m³ for new electronic products and 44 µg/m³ for used products. In the utility room/hall the concentration is 47µg/m³ for new products. To this should be added a possible contribution of up to 476µg/m³ (or 51,000 µg/m³ with spray paint). The Reference Concentration is 0.1 mg/m³, which alone compares to the contribution from electronics in the children room. In case of spray painting the concentrations are so high that direct health damage may be possible, because the exposure is >10 times the occupational limit value. The Reference Dose for xylenes is 0.2 mg/kg bw/d. Six hours exposure for 100 µg/m³ makes a child intake of xylenes of 360 µg/kg bw/d. Thus, alone the electronics make too high exposure compared to Reference dose. A further 10-100 times enhanced exposure, which is likely with contributions from other sources, may be seen as completely unacceptable. In the children’s room the calculated concentrations of styrene are 22 µg/m³ for new electronic products and about 8 µg/m³ for used products. To this should be added possible contributions of about 772 µg/m³ in total from incense, tents to children and tubular pearls. The last figure is close to the WHO air quality value of 800 µg/m³ but below the Reference Concentration of 1 mg/m³, which is based on effects on the central nervous system. The Reference Dose is 0.2 mg/kg bw/d, which is somewhat above a Dutch Tolerable Daily Intake of 120 µg/kg bw/d. Child exposures to a concentration of 20 µg/m³ in 6 hours a day results in an intake of 7 µg styrene/kg bw/d. This is far below various danger limits and without health effects. However, in the worst scenario for the children’s room with use of incense etc. there will be a 20% excess of the Reference dose. The highest concentrations of limonene are also calculated in the children’s room, where the concentration will be around 4 µg/m³ for new electronic products. Potential contributions from, for instance, printed matters and incense of around 341 µg/m³ in total should be added. By-exposure to limonene by storage and consumption of citrus fruits is also possible. Limonene has a tolerable daily intake of 0.1 mg/kg bw/d. A child exposed to a concentration of 4 µg/m³ in 6 hours will have an intake of 1.5 µg/kg bw/d. This level of exposure is completely without health risks for a normal child. However, in the worst case scenario the intake may approach the tolerable. In case of allergy or intolerance even very small concentrations of limonene may be of importance, however, but this will not be a specific problem in relation to limonene in the indoor climate. The available data on the less volatile phthalates, brominated flame retardants and perfluoroalkylated compounds in DEPA’s Consumer Product Reports are very scattered, limited and insufficient to use for an exposure/risk assessment. Therefore, in order to estimate the exposure of the floor crawling children from various sources, this data is complemented with data from other Danish and foreign studies of these chemicals as contaminants in house dust. The most abundant phthalate indoor is di(2-ethylhexyl)phthalate (DEHP). The typical daily child intake of DEHP from all indoor sources will be 10-20 µg/kg bw/d or 100-200 µg/day, however in worst case likely amount to 50-250 µg/kg bw/d or 0.5-2.5 mg/day for a very exposed child playing on a PVC floor. To be added is intake of DEHP with the food, which is estimated to 18 µg/kg bw/d or 180 µg/day for a child, thus, in the same order of magnitude as the ”normal” indoor exposure. This can be compared with the no-adverse-effect level of DEHP in animal feeding experiments with rats, which is 3.7 mg/kg bw/d or 37 mg/day for a child. If rats and crawling children do have a similar susceptibility for DEHP, the safety factor is rather narrow for the mostly exposed children, and that is even without including exposure to other phthalates. The levels of brominated flame retardants (PBDE) in house dusts are very variable but, generally, PBDE occur in concentrations one order of magnitude lower than for phthalates. Maximum concentration may be >20,000 ng PBDE/g dust. The exposure to PBDE via house dust is in the same order of magnitude as in food. This is surprising for persistent organic pollutants, for which the food normally accounts for approximately 90% of human exposure. If the estimated intake of dust is 100 mg/day a child can have an intake of 30 and in seldom cases up to 2,000 ng PBDE/day. This should be compared with an average intake from the food of 40-150 ng/day and about 2000 ng/day for nursing infants, because human milk contains relatively high levels of PBDE. Based hereupon the maximum child intake will be <5 µg/day. Comparison with the Reference Dose (RfD) of 2-10 µg/kg bw/d, which includes sufficient safety factors, shows that only nursing infants may come close to the Reference Dose. Therefore, with the present knowledge, the indoor exposure alone will have no immediate health risks. Perfluoroalkylated compounds (PFAS) are not lipophile. Thus intake of animal fat and food in general will not be so important an exposure source as for the lipophile persistent organic pollutants (POP). Indoor climate seems to be the major source of exposure to these substances. If the daily intakes of house dust are set to 100 mg/day, the daily average exposure of a child will be 200-2,000 ng PFAS and the maximum 8-50 µg PFAS/day or 0.8-5 µg PFAS/kg bw/d. This corresponds very well to the exposure scenarios in DEPA consumer report no. 50 about impregnation agents. The acceptable daily intake for perfluoroalkylated compounds is 3 µg/kg bw/day, which corresponds to the no-effect level for reproductive effects with a safety factor of 1,000. Only in the case of maximum exposure the intake will be unacceptable. However, the present knowledge about the toxicology of PFAS is limited, and these substances may appear to be more dangerous, than the investigations until now have indicated. 7.1.3 Mixed exposureIn a home there may be many different consumer products and e.g. building materials which altogether may release many different substances in a complex mixture. In the reports from the DEPA and in this report the health assessments are mainly based on one substance a time. The combined impacts of more/many substances present in the same time are not evaluated. Children staying indoors are exposed to many substances simultaneously. That means possibility of additive effects, and formation of secondary pollutants. In the classical risk assessment paradigm both substances and group of substances are treated separately ignoring that these combined effects may change the picture completely. Knowledge of such cocktail effects is simply lacking. Therefore, exposures should be reduced, even if there are sufficient safety factors for exposure to single substances. In the DEPA reports the focus is on direct adverse health effects from degassing from particular products. In a broader health perspective issues such as comfort and well-being, including experience of air quality should be taken into account. According to the WHO definition: “Health is not only absence of disease and weaknesses but also a state of complete physical, mental and social well-being”. Many pollution sources indoors, including consumer products and building materials, contribute with bad-smelling substances and impact then the experienced air quality. Both from a health viewpoint and regards how the air quality is experienced indoors, it is important to adjust the amount of supplied outdoor air to the home, thus meeting the demand of ventilation. It is important to take into account that placement of computers and other consumer articles in a room may require increased ventilation. In some occasions in newer, well-insulated and sealed dwellings air flows less than 0.5 h-1, which is required according to current building legislation, and is used in model calculations in this report. There are for instances found dwellings with an air flow of only 0.25 h-1. If everything else was equal that would result in twice as high concentrations. In this connection it is important to focus on source emission control, thus limit emissions from indoor pollution sources as much as possible. Then the need of ventilation will be less and energy be saved. That is especially relevant with the tighten energy requirements in the new building legislation. In a dwelling there will often be an exchange of air between rooms and between neighbours apartments, in this way a source may pollute the air inside other rooms than where the source is located. Thus, many things are determining the healthy status of a dwelling, and there will often be insufficient/lacking data for a total and certain assessment. On this background the following recommendations are stated. 7.2 Recommendations of further studies and actionsIn order to establish a more true/credible basis for assessing the state of health in a Danish dwelling with many consumer articles, the following are recommended:
In addition following actions are recommended:
Fodnoter [18]Knudsen HN, Nielsen PA, Clausen PA, Wilkins CK, Wolkoff P. Sensory evaluation of emissions from selected building products exposed to ozone. Indoor Air 2003;13:223-231. [19]Knudsen HN, Clausen PA, Shibuya H, Wilkins K, Wolkoff P. Indeklimavurdering af linolieholdige building materials. By og Byg Dokumentation 054. Hørsholm: Statens Bygge-forskningsinstitut, 2004.
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