Indoor VOC's
Possible Associations Between VOC Concentrations and Worker Health Symptoms
Analysis of CHBS Data Indicates a Possible Association Between Low Level VOC Exposures and Health Symptoms
Field studies have demonstrated that occupants of office buildings
are exposed to low concentrations of complex mixtures of VOCs that
encompass a number of chemical classes and a broad range of potencies
with respect to their potential to cause sensory irritation. It
is suspected that irritant symptoms experienced by office workers
as part of the "Sick Building Syndrome" or SBS may be related to
these exposures in some way. Using data from the CHBS, seven VOC
exposure metrics were developed and their ability to predict self-reported
SBS irritant symptoms of office workers was tested (Ten
Brinke et al., 1998). The term "exposure metric" refers to the
measurement and mathematical expression of the potential or actual
agent (or combination of agents) that causes an adverse health effect.
The VOC metrics were each evaluated in a multivariate logistic regression
analysis model that was adjusted for other risk factors of confounders
known to affect symptom reporting. One metric developed using principal
components (PC) analysis to account for the highly correlated nature
of indoor VOC mixtures and the presence of potent, but unmeasured
VOCs showed a statistical relationship with some SBS symptoms.
Relative Irritancy and the Development of New VOC Exposure Metrics
A relative irritancy scale for the VOCs measured in the CHBS was
first developed. The scale was based on a mouse bioassay (ASTM
Standard Test Method E981-84 (2000)) that determines the concentration
of an airborne irritant that causes a 50% decrease in the breathing
rate of exposed mice (RD50). The RD50 for each VOC of interest was
referenced to the RD50 for toluene in Table 3.
This shows, for example, that styrene is about 8 times
more potent than toluene and that acetone is about 10 times less
potent. A metric, (Ir*VOC)i, was constructed in which the concentrations
of the individual VOCs are weighted by their relative irritancies
and then summed. All seven VOC exposure metrics are described in
Table 4. The underlying assumption is that each of these provides some measure
of the irritant potency of a VOC mixture.
