RISK FACTORS
There is a complex interaction between the building environment,
infectious agents, allergens, occupational exposures, school environment
and recreational exposures, which contribute to shape the
exposome3.
The amount and impact of CBPs exposure may be influenced by the dose of
disinfectant, the resultant concentration of CBPs in the water and the
air, the number of attending swimmers, temperature of water and air,
ventilation rates in the building, duration of swimming, and the water
turbulence2,87. The three routes of exposure
(inhalation, ingestion and dermal absorption) vary for different age
groups and are affected by several factors (Figure 2 ). Some
conditions related to competitive swimmers are highlighted intable 3 .
Inhalation – Swimming-pool attendants inhale from the atmosphere
just above the water’s surface, and the volume of air inhaled is a
function of the effort intensity and time. In indoor swimming-pools,
individuals also breathe air in the wider area of the building housing
the pool. A correlation between physical activity and THM
concentrations88 has been identified.
Ingestion – Inadvertent water intake in the swimming-pool varies
according to age and sex, with adult women ingesting the least and male
children ingesting the most, especially babies.
Dermal/mucosal absorption - Chlorination of bathing water showed
to change the dermal barrier function, especially of atopic
skin89, the same being expected for chlorination of
the swimming-pool water. Infant swimming practice combined with atopy
has been shown to increase the prevalence of eczema90.
Age seems to be the most relevant personal risk factor for respiratory
and reproductive health effects of CBPs exposure in swimming pools. The
first years of life may be seen as a “window of sensitivity” given the
progressive increase in maturation of respiratory tract and reproductive
system.
Age also directly impacts the other risk factors, including the surface
areas of both the head and the body, the breathing rate and body
weight2. The contribution from each exposure route
changes dramatically for each age group, and the time spent swimming
must also be taken into consideration. Adjusted for body weight, the
uptake of CBPs by all routes is clearly higher in infants or children
and decreases with age. A schematic representation is presented infigure 3 .
As previously mentioned, the use of indoor chlorinated-pools especially
by young children interacts with atopic status to promote the
development of childhood asthma52, and a synergistic
action of exposure to pets and environmental tobacco smoke in
chlorinated-pools attendants predisposes to the development of
asthma51.