Assessment of Consumer Exposure to Phthalates via PVC Flooring and the Associated Risk to Health
The EU Risk Assessments of the phthalates DEHP, DINP, DIDP and
BBP include estimates of exposure to various sectors of the
population via a range of exposure scenarios.
PVC flooring is included in the scenario "indoor air" which also
includes exposure via wallcovering, furniture, etc. The approach
adopted is similar for all the phthalates and is exemplified by
DEHP below.
Exposure
The worst case assumptions made are :
- All surfaces of the room are covered in PVC and the air is
saturated with DEHP vapour.
- Three times more DEHP is bound to dust particles in the air
than is present as vapour
The concentration of DEHP indoors, at 20 C, is calculated from
the saturated vapour pressure to be 5.3 µg/m3. The
amount of DEHP adsorbed onto dust particles is therefore assumed to
be
15.9 µg/m3 (3 x 5.3).
The total air concentration would then be 21.2
µg/m3.
The daily exposure to DEHP in in-door environments for adults
and children is calculated as follows.
The body weight (BW) for an adult is 60 kg and 8 kg for a child.
The inhalation rate, assuming moderate activity (Vinh)
for an adult is 20 m3/day and 9.3 m3/day for
a child.
Uinh is the uptake (mg/kg/day), Binh the
bioavailability for inhalation exposure (75% for adults and 100%
for children), Cinh the air concentration
(mg/m3) and 't' the exposure duration (20h/day for
adults and 22 h/day for children)
Adults
Children
Hazard
The lowest No Observed Adverse Effect Level (NOAEL) for
DEHP is 4.8 mg/kg bw/day. This is the level of DEHP which, when fed
to several generations of rats throughout their lives, caused no
adverse effects whatsoever. It is clearly stated in the DEHP risk
assessment that this is a very conservative, "worst case",
value.
Risk
The risk posed to human health by exposure to DEHP in indoor air
is assessed in terms of the "margin of safety" (MOS) which is the
ratio of the hazard (NOAEL) to the level of exposure, both
expressed in µg/kg body weight/day. A MOS greater than or
equal to 100 is considered to indicate that there is no risk. A MOS
of less than 100 indicates that there is a risk which needs to be
managed.
For DEHP via indoor air :
MOS = 4,800 / 4.4 = 1090 for adults
MOS = 4,800 / 22.4 = 214 for children
On the basis of these MOS the risk assessment concludes that
there are no risks to children or adults from exposure to
phthalates via indoor air.
Worst case assumptions and species differences
It is important to note that the risk assessment takes a
precautionary "worst case" approach with regard to:
- Air concentration. The assumed value of
21µg/m³ is much greater than the many indoor air
measurements which have been made in Europe and the USA. The
highest reliable measured value, including airborne dust, is around
1 µg/m³
- The duration of exposure is 20 and 22 hours
per day for adults and children respectively, with moderate
activity for the whole time.
- Species differences. The risk assessment is
based on an adverse health effect seen in rats. No adverse effect
of phthalates on human health has ever been seen and similarly
non-human primates dosed high levels of phthalates for long periods
of time are also unaffected. Thus by using the rodent data we are
assuming the worst possible case.
Other Phthalates
Similar results are found in the risk assessments for DINP, DIDP
and BBP. However the MOS values are even higher being in the range
2,000 to 500,000.
Dermal Exposure
The possibility that some phthalate could be adsorbed through
the skin from contact with flooring is taken into consideration in
the risk assessments. The exposure via this route is small and when
combined with the exposure via indoor air still gives MOS which
indicate no risk.
Environmental impact of PVC flooring
Some phthalate may be lost from PVC flooring to the environment
during washing. However this has no adverse effect because the risk
assessments conclude that these phthalates all have no adverse
impact on any of the environmental compartments.
Conclusion
The comprehensive and independent risk assessments carried out
on the major phthalates by the EU Member State Experts over the
last six years clearly show that, even using worst case
assumptions, the use of phthalates in PVC flooring poses no risks
to man or the environment.
Further Information
The EU risk assessments are available on the Phthalates
Information Centre Europe web site
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