Other health effects
Many in vitro and in vivo toxicological studies have
provided evidence about genotoxic and cytotoxic effects induced by CBPs
and the WHO International Agency for Research on Cancer acknowledges
sufficient evidence for the carcinogenicity of chloroform and other
widespread CBPs in animals75.
In humans, however, the epidemiologic evidence overall has generally
been considered insufficient to declare CBPs to be carcinogenic, with
bladder cancer presenting the most consistent evidence by providing the
greatest likelihood of causality. It is worth noting that the majority
of the studies evaluate the risk of cancer related to drinking water and
not exposure in swimming-pools, so this lack of evidence should be
considered with concern and not extrapolated. In fact, a recent study
showed that for elite swimmers and their coaches, the levels of THMs in
a Portuguese swimming-pool exceeded the limits for cancer
risk76.
Regarding bladder cancer, several epidemiological studies have evaluated
its risk in relation with CBPs, of which some are of sufficient quality
to provide meaningful evidence towards causal inference, including
meta-analysis77 and two pooled
analyses78,79. While the majority were related to
drinking water, there are also studies finding increased risk of bladder
cancer related to showering, bathing, or swimming exposures to
THM80-82.
Associations with other types of cancer have been suggested, namely
melanoma risk associated with a history of swimming83and colorectal cancer risk with CBPs exposure in drinking
water84.
Regarding reproductive effects, there is no clear evidence linking CBPs
exposure to poor pregnancy outcomes, except for a slight association
with fetal growth-related outcomes and sporadic associations with some
categories of congenital anomalies85.
Potential impact of CBPs on male fertility has been much less studied
and is of great concern given the remarkable permeability of the scrotal
skin. Most studies have addressed mainly the risks related to drinking
water, while one study addressed the exposure through swimming-pool
water and found that adolescents having attended indoor
chlorinated-pools for > 250 h before the age of 10 years or
> 125 h before the age of 7 years were three times more
likely to have an abnormally low serum inhibin B and ⁄ or total
testosterone than their peers who never visited these pools and those
who attended outdoor chlorinated-pools or a copper–silver
pool86.