Risk assessment of boron in glass wool insulation |
| |
Authors: | Allan Astrup Jensen |
| |
Institution: | (1) FORCE Technology, 345 Park Allé, 2605 Broendby, Denmark |
| |
Abstract: | 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. |
| |
Keywords: | Boron Boron compounds Boron intake Glass wool insulation Occupational exposure Risk assessment |
本文献已被 PubMed SpringerLink 等数据库收录! |
|