Environmental Engineering Reference
In-Depth Information
air. SVOCs and particulate organic matter (POM) may be partially in the
vapor phase and partially adsorbed to suspended particles or settled dust,
or to indoor surfaces.
House dust can serve as a reservoir for SVOCs and POM where exposure
may occur as a result of resuspension, ingestion, or dermal contact. Over
230 organic compounds (other than pesticides and polycyclic aromatic
hydrocarbons) have been identified in house dust samples collected in south-
ern Europe. The most commonly detected compounds were fatty acids,
phthalic acid esters, and C
20
-C
35
n
-alkanes. Concentrations were typically
>200
g/g house dust.
Floor dust has also been shown to have significant concentrations of
linear alkylbenzene-sulfonates (LAS), substances widely used as surfactants
in cleaning agents such as soap and detergents. LAS concentrations in the
floor dust of seven Danish public buildings ranged from 34 to 1500
µ
µ
g/g
dust, with clothing being the most important source of LAS.
F. Health effects
It is widely believed in the scientific community that exposures to individual
VOCs or SVOCs in indoor environments are not likely to be responsible for
acute symptoms reported by individuals in buildings. Concentrations are
typically two or more orders of magnitude lower than OSHA permissible
exposure limits (PELs) and American Conference of Governmental Industrial
Hygienists (ACGIH) threshold limit values (TLVs), which have been devel-
oped to protect most workers from adverse health effects (including irrita-
tion) associated with airborne exposures.
VOCs nevertheless have been and continue to be suspected as a cause
of (or a risk factor for) sick building syndrome (SBS)-type symptoms (see
Chapter 7). Reasons for this include: (1) many VOCs have the potential to
cause sensory irritation and central nervous system symptoms characteristic
of SBS, (2) concentrations, though low, are significantly higher indoors than
in the ambient atmosphere, and (3) the potential for the many VOCs present
to cause symptoms as a result of both additive and multiplicative (synergis-
tic) effects.
In response to these concerns, Danish scientists have developed and
tested what is described as the TVOC theory. In the TVOC theory, sensory
irritation and even neurotoxic-type symptoms are thought to be due to the
combined effects of exposure to VOCs. The biological mechanism for this
phenomenon appears to be stimulation of the trigeminal nerve system,
described as the common chemical sense.
1. Common chemical sense
The common chemical sense is one of two olfactory mechanisms by which
humans perceive and respond to odor. The chemical sense organ consists of
trigeminal nerves in the nasal cavity and eyes, as well as facial skin areas.
They can be stimulated by a variety of chemicals as well as physical agents
