VOICE-OVER: Welcome to the ConsExpo Web tutorials for using models...
to estimate consumer exposure by inhalation.
In this introductory tutorial...
you will learn the basics of ConsExpo Web’s inhalation exposure simulations...
which are explained in four stages.
The release of substances from consumer products to the air in a room...
the dispersion of substances through the air...
the inhalation of substances...
and the absorption of inhaled substances into the human body.
Basics of inhalation exposure simulations.
All inhalation models included in ConsExpo Web consist of the same four stages.
First, the substance is introduced into the air in a room...
when released from a consumer product.
Next, the substance is dispersed through the air.
Here, the concentration of the substance in the air...
can be simulated over different periods of time and under varying conditions...
such as ventilation rate, room size or the amount released.
The concentration of the substance in the air is considered to be equal...
to the concentration of the substance in the air...
that is inhaled by the consumer.
Once the substance is inhaled, it may be absorbed into the human body.
While these four stages apply to all ConsExpo Web inhalation models...
ConsExpo Web has separate inhalation models for the release of substances...
that evaporate from a liquid product, are sprayed into the room as droplets...
or evaporate from solid materials.
Release from consumer products.
ConsExpo Web provides different evaporation modes...
to estimate the release of substances into a room...
depending on the product scenario.
In cases where the evaluated substance evaporates from a liquid product...
you should select the exposure to vapour mode for a simulation.
In cases where the consumer uses an aerosol spray...
and the evaluated substance is released into the air as sprayed droplets...
you should select the exposure to spray mode.
Lastly, ConsExpo Web is able to model the evaporation of a substance...
from a product that consists of solid materials.
Examples of cases where you should select the solid materials mode...
are solid construction materials such as wood or limestone...
that are impregnated with substances...
that can evaporate over a prolonged period of time.
All three release modes in ConsExpo Web...
calculate the amount of a substance released over time.
The ConsExpo Web user needs to select the release modes...
that is most suitable for the specific consumer exposure scenario.
ConsExpo Web has general input fields...
that are used to simulate the inhalation exposure event...
and are common to all three release modes.
These general input fields will be explained in this introductory ConsExpo Web tutorial.
The general input fields are in the scenario description...
for example the frequency at which the consumer is exposed...
scenario setting, such as the weight fraction of the substance in the product...
the parameters needed for ConsExpo Web to simulate the dispersion through the air...
such as the ventilation rate and the room volume...
and finally the inhalation rate of the consumer...
and the absorption of the substance upon inhalation.
Dispersion through the air in the room.
Room volume is an important parameter...
for calculating the concentration of the substance in the air.
The concentration in the air is calculated...
by dividing the amount of substance present in the air...
by the volume of air in the room.
Therefore, the concentration in the air is inversely proportional...
to the volume of the room.
Another important parameter required to calculate the concentration in the air...
is the ventilation rate of the room.
The concentration of a substance in the air...
is inversely proportional to the ventilation rate.
ConsExpo Web requires a ventilation rate expressed 'per hour'.
This refers to the number of air changes per hour in the room.
One way to calculate the ventilation rate...
is to divide the volume of air leaving the room per hour by the room volume.
For instance, if it takes two hours for a complete change of air in the room...
the ventilation rate is 0.5 per hour.
Since room volume and ventilation rate are general input parameters...
of ConsExpo Web...
you may consult the general fact sheet...
to obtain the appropriate value for your specific consumer exposure scenario.
Here is an overview of the type of rooms described in the general fact sheet...
with their respective default room volumes and derived ventilation rates.
Here you see how a graph can be displayed...
that shows the concentration in the air over time...
calculated by ConsExpo Web in an inhalation exposure simulation.
You can find graphs like this one on the 'Graphs' tab.
We use it here to explain the output of ConsExpo Web...
regarding concentrations in the air.
The mean event concentration refers...
to the mean concentration of the substance in the room...
over the entire duration of the exposure event.
In this graph, the mean concentration over 100 minutes is 5.5 mg/m3...
which is the same as the mean event concentration found on the 'Results' tab.
ConsExpo Web also calculates a peak concentration.
This peak concentration refers to those 15 minutes...
over which the air concentration is the highest within the exposure duration.
This peak concentration is therefore also known...
as the time-weighted average concentration for 15 minutes...
or the 'TWA 15 min' for short.
'Mean concentration on day of exposure'...
refers to the mean concentration in the air of the substance...
over the entire 24 hours of the day of product use.
As such, the mean concentration on the day of exposure...
is actually the same as the mean event concentration...
multiplied by the usage frequency per day and divided by 24 hours.
The same principle applies to 'Year average concentration'...
which is the same as the mean event concentration...
multiplied by the usage frequency per year and divided by 365 days.
Inhalation.
The inhalation rate and exposure duration...
are general inputs that ConsExpo Web needs...
to calculate the amount of the substance inhaled by the consumer.
In an inhalation exposure scenario, the consumer breaths in the air.
ConsExpo Web simulates the concentration of the substance...
in the inhaled air...
by treating it the same as the concentration in the room air.
The respiratory tract of the consumer is then exposed to the evaluated substance.
ConsExpo Web has a button that users can click...
to calculate an inhalation rate as a function of a consumer's body weight...
as specified in the earlier assessment settings...
and the intensity of the exercise performed by the consumer.
The default exercise types are sleep, rest, light and heavy exercise.
ConsExpo Web users can select the level of exercise...
that is most appropriate for the consumer exposure scenario...
in the calculator settings menu.
The results that ConsExpo Web provides for the inhalation scenarios...
are expressed as 'external event dose' and 'external event dose on day of exposure'.
The external event dose refers to the amount of substance...
inhaled by the consumer during the exposure event...
which is equal to the product of the mean event concentration...
inhalation rate and exposure duration divided by the consumer's body weight.
The external event dose on the day of exposure...
is equal to the external event dose multiplied by the usage frequency per day.
Absorption.
Absorption refers to the process...
by which a substance enters the human body as a result of exposure.
In the inhalation exposure scenarios, this refers to the dose...
that is absorbed by the respiratory tract upon inhalation of a substance.
In ConsExpo Web, the absorbed substance amount...
is estimated using a fraction that is inserted as a fixed value.
If, for example, the user enters a fraction of 50%...
ConsExpo Web will calculate the exposure...
assuming that 50% of the inhaled substance amount...
is absorbed into the human body and the remaining 50% is exhaled.
Next, the internal event dose is derived by multiplying the external event dose...
by the absorption fraction.
Similarly, the internal year average dose is the external event dose...
multiplied by the absorption fraction and the product usage frequency per year.
In summary, this tutorial explained the basics...
of how ConsExpo Web simulates inhalation exposure.
Thank you for listening to the introductory tutorial...
on ConsExpo Web inhalation modelling.
We would like to acknowledge our partners: Health Canada...
the French Agency for Food, Environmental and Occupational Health & Safety...
the German Federal Institute for Risk Assessment...
the Swiss Federal Office of Public Health...
the Netherlands Food and Consumer Product Safety Authority...
and the Dutch Ministry of Health, Welfare and Sport.