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111.
Background, aim and scope Glass wools are man-made vitreous fibres, which consist principally of sodium, calcium and magnesium silicates, but may contain
smaller amounts of other elements, including boron. The boron contents originate from the use of borates in the glass melting
process as a glass former and a flux agent. During the production and application of glass wool insulation products, workers
may legally be exposed to glass fibre up to the occupational limit value, commonly of 1 fibre/cm3. However, in practice, the fibre exposure will be at least ten times lower. Boron is a non-metallic element widely distributed
in nature, where it occurs as boric acid, borates and borosilicates. Humans are mainly exposed to boron via vegetarian food
and drinking water, mineral supplements and various consumer products. Boron is an essential element for plant growth, but
the essentiality for humans is not proven, although intakes of trace amounts of the element seem to be useful for bone health
and proper brain function; higher concentrations of boron, however, may be toxic. In relation to the European Union legislation
on dangerous substances, an EU Expert Group has recommended classifying boric acid and borates with risk phrases for reproductive
toxicity. The aim of this paper is to assess whether the new EU hazard classification of boron compounds should imply that
glass wool products used for building insulation in the future should be labelled, “may impair fertility and cause harm to
the unborn child”, because of the low boron content.
Materials and methods Boron intakes are estimated in a worst-case occupational situation with human exposure to glass wool fibres at the occupational
limit of 1 fibre/cm3 by calculation of the mass of the amount of fibres inhaled during an 8-h work day. Fibres are supposed to be cylinders of
glass with a length of 30 μm, an average diameter of 1.5–2 μm and containing either 1.5% or 3.5% boron. As a worst-case scenario,
the density of the fibres is set to 2,700 kg/m3. The inhalation rate of the individuals at moderate work load was set to 2 m3/h. A worst-case scenario also corresponds to 100% retention and to 100% solubility of the retained fibres in the lungs.
Results With the normal boron content of 1.5% in glass wool fibres for building insulation, the extra daily occupational boron intake/uptake
will be 0.03–0.06 mg B for 5 days a week. For more uncommon glass wool with maximum boron content of 3.5%, the worst-case
daily boron intake/uptake will be 0.08–0.16 mg B. The main boron exposure in the general population is from vegetarian food,
and the average daily dietary intake with food is estimated to 1.2–1.5 mg B/day. In addition, significant intakes may come
with drinking water, especially from mineral water. In some instances, exposure from mineral supplements, cosmetics and other
consumer products may be significant. For example, individuals taking mineral supplements, e.g. for bodybuilding, may have
an additional intake to that of 1–10 mg/day. During the years, various organisations have recommended safe intake values for
boron. Recently, the Scientific Panel on Dietetic Products, Nutrition and Allergies of the European Food Safety Authority
(EFSA) has established the ‘Tolerable Upper Intake Level’ (UL) for the intake of boron (boric acid and borates) at 0.16 mg
B/kg body weight per day or about 10 mg B/day for an adult.
Discussion The calculated, worst-case exposure scenario during an 8-h work day will result in an extra daily boron intake that only corresponds
to about 10% of the average daily adult boron intakes through food and drinks of about 1.5 mg. The inter-individual variations
in boron intakes from foods, water and supplements will be much greater than an eventual, very worst-case, additional intake
of boron from inhalation of glass wool fibres. In addition, the combined intakes are far lower than the ‘Tolerable Upper Intake
Level’ of 10 mg B/day for a person weighing 60 kg, as recommended by the European Food Safety Agency. The potential boron
intake from inhalation of glass wool fibres is also much lower than boron intakes by workers in the boron industry, who at
the present occupational limit value will be exposed to 50 mg of boron 5 days a week, or 100 times more than the worst case
for glass wool fibres. Furthermore, in practice, exposure levels will mostly be ten to 100 times lower than the occupational
limit used here as a worst case.
Conclusions The estimated boron intake from inhalation of glass wool fibres in occupational settings will be insignificant and without
any health risks, even in the case of non-compliance with the occupational limit value. Any proposal requiring hazard labels
on commercial glass wool products for building insulation, because of the boron content, is not supported by the present scientific knowledge.
Recommendations and perspectives The European Commission should ensure that the new EU hazard classification of boron compounds is not applied to commercial
glass wool products for building insulation having a low content of boron. 相似文献
112.
文章对外墙外保温系统及其构成进行了分析,讨论了外墙外保温系统EPS(external-wall exteriorpolystyrene granule insulation system)对室内温度的影响。EPS系统能够增加墙体热绝缘系数,改善墙体的温度分布,改变室内的温度分布,减少室内温度受室外环境的影响。降低采暖能耗,节约能源,减少环境污染。 相似文献
113.
依据多年从事环境污染治理的经验,设计出治理锅炉风机噪声的隔声室,并对该隔声室的制造、治理效果进行了评价,得出了该隔声室是控制噪声污染的有效设备。 相似文献
114.
115.
前期试验表明,表面设置厚度20 mm的某非膨胀型防火涂料可较好地抑制高强混凝土的高温爆裂.本文通过试验反算给出了该涂料对应不同温度区间的平均导温系数;随后,利用结构抗火分析软件SAFIR对表面设置该涂料的高强混凝土柱的耐火极限进行了计算分析,考察了截面尺寸、轴压比、荷载偏心率及配筋率等因素的影响,在此基础上提出了相应的... 相似文献
116.
为了正确评估钢筋混凝土构件在实际火灾中的隔火作用,以一般室内火灾轰燃后的房间平均温度-时间曲线为升温曲线,以热传导理论为基础,以钢筋混凝土隔火构件的背火面的最高温度恰好达到220℃为判定准则,用数值计算方法给出钢筋混凝土隔火构件的最小厚度,并用最小二乘法导出其计算公式.火灾房间火灾荷载越大,开口因子越小,最小隔火厚度越大;反之越小.该文所给最小厚度可用于钢筋混凝土分隔构件的性能化耐火设计与评估:当火灾荷载密度较大,开口因子较小时加大构件的厚度以获得安全性,反之,减小厚度以获得经济性. 相似文献
117.
118.
对几个城市已开发的地下公共建筑进行噪声源调查测定,分析地下建筑内带共性的噪声源房间,如风机房、水泵房、地下柴油发电机组等,和不同使用功能的地下建筑声环境要求进行比较,并就地下现有隔空气声结构的隔声测定结果进行初步分析和评价,为今后人防地下建筑设计提供参考。 相似文献
119.
针对国内现有的外墙外保温系统的防火性较差的现状,通过分析上海公寓楼外墙保温层的火灾,得到外墙外保温防火的三种重要因素(粘结或固定方式、防火隔离带的构造、防火保护面层)。鉴于现在流行的保温材料为膨胀聚苯板(EPS),因而选用EPS作为模拟材料,利用数值模拟计算得出以下结论:认为火灾时有空腔的保温层比无空腔的保温层更危险;设置防火隔离带能有效得阻隔火灾的蔓延,较宽的隔离带效果更好。除此之外,外保温层防火设计中还应考虑以下三方面的问题,即遴选适当的保温材料、建议保温层也使用类似于防火分区的防火措施和保证保温效果的同时增加防火隔离带的宽度。研究结论和建议对于解决外墙保温体系防火问题具有重要的参考价值和现实意义。 相似文献
120.
Material selection in manufacturing may be characterized as a series of trade-offs between characteristics, properties, environmental impacts, sustainability, availability, and economics. Societal concerns about the environmental impacts of construction practices and materials have been expressed through an increase in the demand, production and use of “green” building products. This, combined with a desire to integrate more bioproducts and natural and renewable resources into the construction industry, has extended to the production and promotion of insulation made from sheep's wool.Although substantial literature exists on the insulation properties and other benefits of wool, less is known about the economics and manufacturing processes of sheep's wool insulation at varying scales of production. This paper contributes to this field of enquiry through presentation of the preliminary results of a wool insulation manufacturing pilot project, in which the scale and economics of the production of sheep's wool insulation were considered. Processing techniques, the impact of sheep breed, yield, energy use, and manufacturing costs were also examined. The results of the pilot project indicate that, while sheep's wool insulation produced at a smaller, or artisanal scale shows some potential, scale of operation and volume of production need to be carefully considered in order to ensure long-term sustainability of the operation. Using the least expensive sheep's wool available for the manufacture of wool batt insulation (and thereby reducing production costs) did not, in this pilot study, have a negative impact on productivity or product performance. Diversion of this waste stream of currently less marketable, and consequently less valuable wool, into the production of a green building material may offer small but significant benefit to sheep producers and the broader agricultural community, as well as consumers. 相似文献