Emissions of semi-volatile organic compounds (SVOC)

In document Hazardous chemicals in construction products (Page 42-45)

SVOCs can occur in indoor air in both gas and particle phases and commonly occur in different indoor environments. SVOCs are often used in construction products to modify the function, but they also occur in other consumer products, such as electronics, furniture and clothing. The substances which can occur in construction products include biocides and preservatives (e.g. triclosan, pentachlorophenol), pesticides (e.g. chlordane), flame retardants (e.g. decabromodiphenyl ether, tri(chloropropyl)phosphate) and plasticisers (e.g. triphenyl phosphate, di-2-ethylhexyl phthalate (DEHP)).

The use of SVOCs has changed during recent decades. A number of substances have been banned or had restrictions imposed on them, such as tri(chloropropyl)phosphate, pesticides and herbicides such as aldrin, chlordane and DDT, and phthalates such as di-n-butyl

65 AgBB (Committee for Health-related Evaluation of Building Products). This committee’s job is to assess construction products’ health effects.

66 WP 3 & 4: Emissions from wall and ceiling materials: assessing the feasibility of extending the Belgian Royal Decree (8th May 2014) on maximum emission levels from construction products., Katleen De Brouwere, Marc Lor, Study accomplished under the authority of Federal Public Service of Public Health, March 2015.

phthalate, di-isobutyl phthalate, butylbenzyl phthalate and diethylhexyl phthalate. On the other hand, the use of other substances has increased (e.g. 4-nonylphenol or alternative plasticisers such as triphenyl phosphate, diisononyl 1,2-cyclohexanedicarboxylic acid and diethylhexyl terephthalate).

In the case of SVOCs, the inherent physical/chemical properties, such as a low vapour pressure and low aqueous solubility, drives the emissions. The concentration of a SVOC in a material is less relevant for the extent of the emissions than for VOCs where the concentration is the key factor influencing the extent of the emissions. Another fundamental difference between VOCs and SVOCs is that VOCs are emitted from the material regardless of the surrounding environment and their concentration reduces over time during the product’s life cycle. On the other hand, emissions of SVOCs such as plasticisers, flame retardants and preservatives mainly depend on external factors such as distribution in the gas phase and distribution on surfaces, as well as on the characteristics of the substance and material. Although the quantity of SVOCs emitted from a material is very often small compared to the total concentration in the product, emissions can often continue throughout the product’s entire life cycle, thereby affecting the indoor environment for long periods of time67.

SVOCs which are emitted from construction materials into indoor environments can be found in the air, both in the gas phase and bound to particles, but they can also be deposited on different surfaces and accumulate in dust68. Dust can give a more comprehensive picture of the impact from SVOCs in a particular indoor environment and may be a significant pathway in terms of exposure for young children. Concentrations of a number of SVOCs in dust from residential buildings, pre-school institutions, schools and offices are documented in scientific publications69. Articles published recently have highlighted three pathways for transferring SVOCs to dust: evaporation from a material, with the substance then being deposited in the dust70, transfer to dust via fibres and particles formed through abrasion71 and direct transfer to dust upon contact72.

Otherwise, the literature available is very limited about direct measurements of SVOC

emissions from construction products into indoor air. SVOCs have also been measured in air, and for instance dioxin-like PCBs (PCB 105, PCB 118, PCB 156, PCB 167), even though such PCBs have been banned since 1978, and 2,3,7,8-TCDF (2,3,7,8-tetrachlorodibenzofuran) have been found in rooms with PCB-coated ceiling panels73. Emissions of 13 different

brominated flame retardants, BDEs, have been estimated in another study based on

67 Weschler C.J., 2009. Changes in indoor pollutants since the 1950s. Atmospheric Environment 43, 153-169. 68 Weschler C.J., Nazaroff W.W., 2008. Semivolatile organic compounds in indoor environments. Atmospheric Environment 42, 9018-9040.

69 Weschler C.J., Nazaroff W.W., 2010. SVOC partitioning between the gas phase and settled indoor dust. Atmospheric Environment 44, 3609-3620.

70 Rauert C., Harrad S., Stranger M., Lazarov B., 2015. Test chamber investigation of the volatilization from source materials of brominated flame retardants and their subsequent deposition to indoor dust. Indoor Air, 25(4), 393-404.

71 Rauert C., Harrad S., Suzuki G, Takigami H., Uchida N., Takata K., 2014. Test chamber and forensic microscopy investigation of the transfer of brominated flame retardants into indoor dust via abrasion of source materials. Science of the Total Environment, 493, 639-648.

72 Rauert C., Harrad S., 2015. Mass transfer of PBDEs from plastic TV casing to indoor dust via three migration pathways – A test chamber investigation. Science of the Total Environment, 1(536), 568-74.

73 Volland G., Hansen D., Zöltzer D., 2007. Dangerous substances in building materials – Emissions from PCB coated ceiling panels – Polychlorinated Biphenyls (PCB) in indoor air. In: Grosse C.U.: Advances in

Construction Materials, pp. 691-696. Springer-Verlag Berlin Heidelberg 2007. ISBN-13 978-540-72447-6.

concentration measurements in indoor air74. The largest proportion of these BDEs occurs in floor dust, but around 20% is emitted into the air in a gas phase or as airborne particles. Emissions have been reported for the flame retardants tris-(2-chloroisopropyl) phosphate (TCPP) and hexabromocyclododecane (HBCDD) from insulating panels made of different materials (polystyrene, polyisocyanourate, polyurethane)75. The HBCDD emissions are extremely low, while TCPP emissions from one panel were several hundred times lower than those from the other material, which was probably due to the material’s composition and structure.

DEHP emissions have been analysed both in experimental tests76, 77 and using mathematical models78, taking into account emissions during a standard procedure and as a function of temperature79, relative air humidity80 and air flow81. The emissions were heavily dependent on temperature, moderately dependent on air renewal cycles and independent of relative air humidity.

A more detailed description of emissions data reported in the scientific literature is provided in the consultant’s report82, with a summary also being provided in Appendix 6.

The Swedish Chemicals Agency has previously investigated the presence of and exposure to phthalates, where the occurrence in construction products turned out to be a significant source of exposure83. Phthalates commonly occur in construction products such as cables, wires, floors, plastic foil and film, tubes, gaskets, wall coverings for wet rooms and coated

textiles/fabrics. These products are wholly or partly made of soft, plasticised PVC. Phthalates are also used in chemical products such as paint, sealants, adhesives and coating agents. The phthalates are not chemically bonded to the material, which means that they can be emitted from materials. Constant emissions of phthalates mean that people can be exposed, including through direct contact with the dust, and phthalates can subsequently be absorbed by the body. Foetuses and small children are considered to be a sensitive risk group as young laboratory animals have shown to be more sensitive to phthalates than adult animals.

74 Batterman S.A., Chernyak S., Jia C., Godwin C., Charles S., 2009. Concentrations and emissions of polybrominated diphenyl ethers from U.S. houses and garages. Environmental Science and Technology 43, 2693-2700.

75 Kemmlein S., Hahn O., Jann O., 2003. Emissions of organophosphate and bromine flame retardants from selected consumer products and building materials. Atmospheric Environment 37, 5485-5493.

76 Afshari A., Gunnarsen L., Clausen P.A., Hansen V., 2004. Emission of phthalates from PVC and other materials. Indoor Air 14, 120-128.

77 Clausen P-A., Hansen V., Gunnarsen L., Afshari A., Wolkoff P., 2004. Emission of Di-2-ethylhexyl phthalate from PVC flooring into air and uptake in dust: Emission and sorption experiments in FLEC and CLIMPAQ. Environmental Science and Technology 38, 2531-2537.

78 Clausen P.A., Liu Z., Xu Y., Kofoed-Sorensen V., Little, J.C., 2010. Influence of air flow rate on emission of DEHP from vinyl flooring in the emission cell FLEC: Measurements and CFD simulation. Atmospheric Environment 44, 2760-2766.

79 Clausen P.A., Liu Z., Kofoed-Sorensen V., Little J.C., Wolkoff P., 2012. Influence of temperature on the emission of Di-(2-ethylhexyl)phthalate (DEHP) from PVC flooring in the emission cell FLEC. Environmental Science and Technology 46, 909-915.

80 Clausen P.A., Xu Y., Kofoed-Sørensen V., Little J.C., Wolkoff P., 2007. The influence of humidity on the emission od di-(2-ethylhexyl) phthalate (DEHP) from vinyl flooring in the emission cell “FLEC”. Atmospheric Environment 41, 3217-3224.

81 Clausen P.A., Liu Z., Xu Y., Kofoed-Sorensen V., Little, J.C., 2010. Influence of air flow rate on emission of DEHP from vinyl flooring in the emission cell FLEC: Measurements and CFD simulation. Atmospheric Environment 44, 2760-2766.

82 Swedish Chemicals Agency 2015, PM 9/15, Kartläggning av farliga ämnen i byggprodukter i Sverige (Survey of hazardous substances in construction products in Sweden), IVL

83 Swedish Chemicals Agency 2014, Report 4/15, Phthalates which are toxic for reproduction and endocrine- disrupting – proposals for a phase-out in Sweden

Phthalates in the indoor environment are an important source of exposure for small children where a considerable contribution is made, above all, by the occurrence of phthalates in dust84. Children have a higher respiratory rate than adults and breathe more air in relation to their body weight than adults. They are often close to the floor and have a habit of putting hands and objects in their mouth. Children have a high intake of dust, estimated at up to 100 mg/kg body weight per day.

Concentrations of phthalates in dust are generally higher in the pre-school environment, up to five times higher than in the home or other public environments. This can be attributed to the desire to have easy-to-clean surfaces in pre-school institutions, which means that PVC materials are often used. Measurements of phthalates in dust from pre-school institutions indicated higher total concentrations in older buildings than in newly built premises and which phthalates were found also differed. One explanation for the higher concentrations in older pre-school institutions may be that there is a higher level of wear and tear.

Based on children’s intake of dust and the phthalate concentrations measured, dust posed for small children a level of exposure to DEHP equivalent to roughly half the limit stipulated for effects which are toxic for reproduction. Dust also made a significant contribution to the presence of DINP, while there was a somewhat lower level of exposure to DIDP, BBP and DBP from dust.

5

Initiative for phasing out hazardous substances

in the construction sector

The construction sector has been actively involved with environmental issues since the early 1990s. The Swedish Eco-cycle Bill 1992/93:180 indicated construction products as being a group of articles considered appropriate for producer’s liability. The eco-cycle delegation set up by the Government proposed the introduction of producer’s liability for construction products85. This could happen either by the sector making voluntary commitments or in the form of a binding government ordinance. The sector chose to make a voluntary commitment and, in 1994, the construction sector’s Ecocycle Council was set up. The work of the

Ecocycle Council was then formed the basis for the majority of the initiatives described in this chapter. This Ecocycle Council no longer exists nowadays.

In document Hazardous chemicals in construction products (Page 42-45)