High Trihalomethane Levels Found In Pools

InfoTrac Web: Health Reference Center-Academic.
Source: Occupational and Environmental Medicine, April 2002 v59 i4
p243(5).

Title: Distribution and determinants of trihalomethane concentrations in
indoor swimming pools. (Original Article).(Statistical Data
Included)

Author: H. Chu and M.J. Nieuwenhuijsen

Subjects: Trihalomethanes - Health aspects
Swimming pools - Health aspects
Chlorination - Health aspects
Water quality - Measurement
Locations: United Kingdom

Electronic Collection: A85700036
RN: A85700036

Objectives: For many decades chlorination has been used as a major
disinfectant process for public drinking and swimming pool water in many
countries. However, there has been rising concern over the possible link
between disinfectant byproducts (DBPs) and adverse reproductive outcomes. The
purpose of this study was to estimate the concentrations of trihalomethanes
(THMs) in some indoor swimming pools in London and their variation within and
between pools and any correlation with other factors.

Methods: Water samples were collected from eight different indoor swimming
pools in London. A total of 44 pool samples were collected and analysed for
total organic content (TOC) and THMs. Water and air temperature were measured
along with the pH during the collection of pool samples. The level of
turbulence and the number of people in the pool at the time were also
assessed.

Results: The geometric mean concentration for all swimming pools of TOC was
5.8 mg/l, of total THMs (TTHMs) 132.4 [micro]g/l, and for chloroform 113.3
[micro]g/l. There was a clear positive linear correlation between the number
of people in the swimming pool and concentrations of TTHMs and chloroform
(r=0.7, p<0.01), and a good correlation between concentrations of TOC and
TTHMs (r=0.5, p<0.05) and water temperature and concentrations of TTHMs
(r=0.5, p<0.0l). There was a larger variation in THMs within pools than
between pools.

Conclusion: Relatively high concentrations of THMs were found in London's
indoor swimming pools. The levels correlated with the number of people in the
pool, water temperature, and TOC. The variation in concentrations of THMs was
greater within pools than between pools.

**********

Chlorination is a process whereby harmful pathogens are eliminated from the
water. During this process, not only unwanted micro-organisms are removed but
several organic halogenated compounds known as chlorination disinfection
byproducts (DBPs) are formed at the same time (1). Excessive exposure to DBPs
may be harmful to humans. (2)

Trihalomethanes (THMs), generally the most common DBPs, are volatile
halogenated hydrocarbons, which can vaporise from water into the atmosphere.
When chlorine is added to the water, it reacts with the organic matter in the
water such as skin scales and residuals from body care products to form
various DBPs, including THMs. (1 3) The THMs include chloroform
([CHCl.sub.3]), bromodichloromethane (BDCM) ([CHCl.sub.2]Br),
chlorodibromomethane (CDBM) (CHCl[Br.sub.2]), and bromoform ([CHBr.sub.3]). In
general, chloroform is the most common occurring THM. The International Agency
for Research on Cancer has classified chloroform as a 2B carcinogen.

Adverse reproductive outcomes such as spontaneous abortion, birthweight,
neural tube defects, urinary tract defects, and others have been associated
with exposure to THMs, but the evidence so far seems to be inconsistent and
inconclusive. (4)

There are three different exposure routes--ingestion, inhalation, and dermal
absorption--and all routes can contribute to the total uptake of THMs. (1 5)
Everyday pathways include drinking tap water, showering, bathing, washing up,
and boiling water. For swimmers, the greatest uptake is likely to be through
dermal absorption because a large surface area of skin is exposed and
inhalation from the air above the pool water surface. (1) The rate of
inhalation depends on the intensity of the exercise.

Weisel and Shepard (6) measured mean chloroform concentrations of 85
[micro]g/l in the water and 87 [micro]g/[m.sup.3] in air in swimming pools.
Lindstrom et al (7) reported chloroform concentrations of 68 and 73 [micro]g/l
in the water. Matthiessen and Jentsch (8) measured mean concentrations of THMs
of 29.7 [micro]g/l in water and 142 micro/g[m.sup.3] in air in swimming pools
in Germany. Slightly lower concentrations were measured in both air and water
by Camman and Hubner (9) in Germany. They also measured CDBM, BDCM, and
bromoform, but the concentrations of these were much lower than chloroform
with a maximum of 6.51 [micro]g/l of CDBM in water and 22.4 [micro]g/[m.sup.3]
for BDCM in air. In Holland, Aiking et al (10) measured concentrations of
chloroform in water of 18.4 [micro]g/l in indoor pools and 24.0 [micro]g/l in
outdoor pools. Aggazzotti et al (11-14) conducted a series of studies in
Modena, Italy, and found correlations between chloroform concentrations in air
and water and the number of swimmer s, (11 13) and chloroform concentration in
water and free and combined chlorine residual and water pH, (11) but these
were generally only weak to moderate correlations.

At present there are few publications on the amount of total organic content
(TOC) and concentrations of THMs in United Kingdom swimming pools. Therefore,
this study aims to provide a greater understanding of the concentrations of
THMs in United Kingdom indoor swimming pools, the variability in these
concentrations, and any correlation with other factors.

METHODS

Sampling

A list of indoor swimming pools in London was obtained from Sportline, a
sports telephone information service. A total of 29 swimming pools were
identified and eight were chosen to take part in this project. The indoor
swimming pools were primarily chosen for convenience of travelling to collect
samples. (15)

The swimming pool water sampling was conducted between 19 June 2000 and 14
July 2000. For each pool at least one sample was collected once every week for
3 consecutive weeks. In some pools two samples were collected at the same time
to estimate the coefficient of variation. Pool samples were collected in 150
ml brown bottles for analysis of both THMs and TOC. The bottles were filled to
the top and the caps were tightly sealed with a screw cap to prevent THMs
volatising into the environment. Samples were refrigerated and stored until
the end of the week when they were sent to the Thames Water Quality Centre, a
United Kingdom Accredited Scheme laboratory in Reading, to be analysed. Also,
a few samples of tap water were taken for comparison.

Water and air temperature, pH, turbulence, and the number of people in the
pool were recorded when the samples were collected.

Laboratory analysis

The method of TOC analysis was based on that described in the instrumental
measurement of total organic carbon, total oxygen demand, and related factors.
(16) An O.I. model 700 Carbon analyser was used to analyse the concentration
of TOC. Samples were firstly treated with phosphoric acid, then by nitrogen to
convert organic carbon to carbon dioxide. The samples were then treated with a
sodium persulphate solution at 100[degrees]C, then by nitrogen to convert any
organic carbon left to carbon dioxide. The carbon dioxide was trapped and
concentrated on an absorbent where it was heated rapidly, and measurements
were taken with an infrared detector. This process took about 10 minutes a
sample. The detection limit for TOC was 0.1 mg/l.

The THMs analysis was based on the method described for chloro- and
bromo-trihalomethanated methane in water (17) and halogenated solvents and
haloforms in water using a static headspace technique. (18) This method can
detect chloroform, bromoform, CDBM, BDCM, trichloroethene, trichloroethane
(1,1,1), and carbon tetrachloride. The samples were individually sealed in a
vial fitted with a crimp on septum cap. The samples were equilibrated at
70[degrees]C for 27 minutes in a Perkin Elmer HS 101 headspace analyser. A
subportion of the headspace gas was then transferred through a needle
(100[degrees]C) and transfer line (120[degrees]C) to a Perkin Elmer 8500 gas
chromatograph fitted with a capillary column (HP5 25 mx0.32 mm or equivalent).
Oven temperature started at 40[degrees]C and ramped up at 25[degrees]C/minute
to 163[degrees]C after 5.5 minutes isothermal time. Detection took place with
an ECD detector (300[degrees]C). The injector temperature was 150[degrees]C.

The samples had to be in equilibrium before processing. The distribution of a
liquid is directly proportional to the distribution of its vapour. The samples
were individually sealed in a vial fitted with a crimp on septum cap. The vial
was left in an oven for a fixed time for headspace gas equilibrium with the
sample. The vial was then punctured and samples were transferred onto a
capillary gas chromatograph, where the components were then separated and
measured. Full quality control procedures were in place. The detection limit
for each of chloroform, bromoform, BDCM, CDBM, and trichloroethene was 2.5
[micro]g/l, for trichloroethane (1,1,1), and tetrachloroethene 1.0 [micro]g/l,
and for carbon tetrachloride 0.3 [micro]g/l. Concentrations of
trichloroethene, trichloroethane (1,1,1), and carbon tetrachloride were all
below the limit of detection and are not further described in this paper.

The coefficient of variation of the method was calculated (table 1). The
coefficients of variation (%) were low. Most were below 5% variability but TOC
showed a 13.4% coefficient of variation.

Statistical analysis

The analyses were carried out using statistical software SPSS. Spearman rank
correlation was used to estimate the correlation between the various
variables. A one way analysis of variance (ANOVA) model was used to estimate
the swimming pool variance components.

RESULTS

Concentrations

A summary of the swimming pool concentrations is shown in table 2. The
arithmetic mean (AM) of TOC concentration of the swimming pools was 6.3 mg/l,
compared with 2.3 mg/l in tap water in London. The AM of chloroform was 121.1
[micro]g/l in the swimming pools and 3.5 [micro]g/l in tap water. Similar BDCM
concentrations were found in swimming pools and tap water samples; 8.3
[micro]g/l and 7.5 [micro]g/l, respectively.

Variance within and between swimming pools

The variances within and between swimming pool components were estimated and
concentrations of chloroform, BDCM, CDBM, and TTHMs were found to have a much
greater variation within pools than between pools whereas TOG had a greater
variation between pools (table 3).

Correlation

Correlation coefficients are shown in table 4. The concentrations of TOG and
TTHMs showed a good correlation; where TOG increased, TTHMs increased (r=0.5,
p<0.05, fig 1). A positive linear correlation was found between water
temperature and the TTHMs (r=0.5, p<0.01, fig 2). The strongest correlation
was found for the number of people in the swimming pools and concentrations of
TTHMs and chloroform (r=0.7, p<0.01, fig 3).

DISCUSSION

The main findings of this study were: (a) that there are relatively high
concentrations of TTHMs in indoor swimming pools in London, (b) that the
variation in concentrations of TOG was greater between pools whereas for
chloroform, BDGM, and GDBM variation was greater within pools, (c) that there
were strong correlations between concentrations of TTHMs and chloroform, TOG,
water temperature, and the number of people in the swimming pools.

Concentration of TTHMs

The concentrations of chloroform collected in these swimming pools were found
to be relatively high compared with other studies conducted outside the United
Kingdom. In Italy, Aggazzotti et al(11-14) found concentrations of 17-47
[micro]g/l of chloroform in the water and 66-653 [micro]g/m(3) of chloroform
in the air. For non-competitive swimmers, a mean of 0.4 [micro]g/l chloroform
was found in the blood between 1 and 40 minutes after exposure. Weisel and
Shepard(6) measured mean chloroform concentrations of 85 [micro]g/l in the
water and 87 in air in swimming pools, but other studies(7 9 10) found much
lower concentrations in their swimming pool studies. The concentrations of
TTHMs in London swimming pools were also considerably higher than the
concentrations in tap water.

Individual THMs: variation within and between pools

Although other studies generally focused on one swimming pool we included
several pools and estimated the variance components within and between pools.
The analyses showed that most variance in TOG was between swimming pools. This
is probably because TOG is affected by few factors--such as the number of
people in the swimming pool. Chloroform, BDGM, CDBM, and TTHms concentrations
varied more within the swimming pools. These concentrations depend on a more
complex set of factors--such as the amount of TOG in the water, pH,
temperature, and number of people.

Correlation

Concentrations of TOG and chloroform were correlated and this is not
surprising as when chlorine is added to water, it reacts with some components
of TOG to form chloroform. Concentrations of TOG in tap water were almost
three times lower than those in swimming pools, and this suggests that the
greatest proportion of the TOC originated in the pool possibly from the
swimmers. Concentrations of TOC should be reduced as far as is reasonably
practicable to reduce the formation of THMs.

Concentrations of TTHMs were also correlated with the temperature of swimming
pool water. As water temperature rose, more chloroform was formed, especially
in indoor swimming pools, in which water and air temperature are generally
higher than in outdoor swimming pools, and therefore more TTHMs are likely to
be formed in both water and air.

The number of people in the swimming pool was positively correlated with the
concentrations of TTHMs and chloroform. Also Aggazzotti et al (14) found that
the number of people in the swimming pools affected the concentration of
TTHMs. In one study they found that 40-50 competitive swimmers in the pool
doubled the concentration of TTHMs in air and water compared with a pool
without swimmers. The TTHMs and chloroform concentrations in the water
increased probably because as there were more swimmers in the pool, the
turbulence and splashes increased and more organic material was released,
which allowed TTHMs to form.

Uptake of THMs

In this study we only measured the THMs concentrations in water, but some
other studies have measured the actual uptake, which was consiberable.
Levesque et al (19) measured the body burden (based upon 11 male swimmers)
resulting from exposure to chloroform in water and air of an indoor swimming
pool. A 1 hour swim was postulated to result in a chloroform dose of 65
[micro]g/kg/day, 141 times the dose from a 10 minute shower (0.46
[micro]g/kg/day) (19) and 93 times greater than exposure by ingestion of tap
water as demonstrated by Jo et al. (20) Lindstrom et al (7) estimated that the
dermal route of exposure accounted for 80% of the blood chloroform
concentration during swimming. Aggazotti et al (11) found a correlation
between chloroform concentrations in plasma and number of swimmers ([r.sub.s]
= 0.32), time spent swimming ([r.sub.s] = 0.57), chloroform concentrations in
water ([r.sub.s] = 0.48), and chloroform concentrations in environmental air
([r.sub.s] = 0.74), whereas 4.7% of the variance in plasma co ncentrations was
explained by the intensity of physical activity. Aggazotti et al (14) reported
a mean chloroform uptake of 25.8 [micro]g/h (range 22-28 [micro]g/h) at rest
and 176.8 [micro]g/h (134-209 [micro]g/h) after 1 hour swimming (arithmetic
mean of chloroform concentration in pool water was 33.7 [micro]g/l). Lower
concentrations of uptake were reported for CDBM and BDCM. Also other studies,
[6,8-10] recorded considerable uptake of chloroform during swimming. Potential
uptake for people swimming in the pools in this study is likely to be higher
than reported in other studies as the concentration of THMs in water were
higher. However, it is important to note that inhalation is an important route
of exposure and the uptake through this route is affected by various factors
including for example, the number of swimmers, turbulence, and breathing rate.
As we did not take any measurements in air it is difficult to estimate the
actual uptake in our population.

Implications of risk to health

Most of the reproductive health studies of DBPs have been carried out focusing
on drinking water. Swimming seems to have a greater risk of exposure to DBPs
as uptake may occur through three different routes; inhalation, dermal
absorption, and, to a certain extent, ingestion and the amount of TTHMs
concentration seems to be higher compared with drinking water. Therefore it is
essential to gain a better understanding of the possible determinants of TTHMs
in swimming pools and this pathway should be included in epidemiological
studies where possible. Of course it is important to remember that a major
determinant of the total uptake is likely to be the frequency and duration of
swimming and more information should be collected on this to allow the
estimation of any potential health risks.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]
Table 1

Coefficient of variation for the methods and analysis of TOC and
trihalomethanes

Variables Coefficient of variation (%)

TOC 13.4
Chloroform 3.9
BDCM 4.2
CDBM 2.0
TTHM 3.3
Table 2

Characteristics of trihalomethanes and other factors in United Kingdom
swimming pools

Samples (n) Arithmetric mean

Chloroform ([micro]g/l) 24 121.1
BDCM ([micro]g/l) 24 8.3
CDBM ([micro]g/l) 24 2.7
Bromoform ([micro]g/l) 24 0.9
TTHM ([micro]g/l) 24 132.4
TOC (mg/l) 24 6.3
Air temperature ([degrees]C) 24 26.9
Water temperature ([degrees]C) 24 31.1
pH 24 7.4
People (n) 24 7.1

Geometric Mean Geometric SD Minimum

Chloroform ([micro]g/l) 113.3 1.5 4.5
BDCM ([micro]g/l) 6.9 1.8 2.5
CDBM ([micro]g/l) 2.0 2.3 0.67
Bromoform ([micro]g/l) 0.8 1.5 0.67
TTHM ([micro]g/l) 125.2 1.4 57
TOC (mg/l) 5.8 1.5 3.3
Air temperature ([degrees]C) 26.8 1.1 22.3
Water temperature ([degrees]C) 31.0 1.1 27.5
pH 7.4 1.0 7
People (n) 5.9 1.9 1

Maximum

Chloroform ([micro]g/l) 212
BDCM ([micro]g/l) 23
CDBM ([micro]g/l) 7
Bromoform ([micro]g/l) 2
TTHM ([micro]g/l) 222.5
TOC (mg/l) 12.9
Air temperature ([degrees]C) 34
Water temperature ([degrees]C) 34.5
pH 8.13
People (n) 16
Table 3

Within and between pool variance components (%) of trihalomethanes and
TOC in eight United Kingdom swimming pools

Variables [Q.sub.w] [Q.sub.w] (%) [Q.sub.b] [Q.sub.b] (%)

TOC 2.3 31 5.0 69
Chloroform 1581.9 77 467.6 23
BDCM 34.2 96 1.4 4
CDBM 4.2 93 0.3 7
TTHM 0.1 79 0.027 21

[Q.sub.b], between pool variance; [Q.sub.w], within pool variance; %,
percentage of total variance.
Table 4

Spearman correlation coefficients of trihalomethanes and other factors
in United Kingdom swimming pools (n=24)

Spearman
correlation
Variables coefficient p Value

TOC v chloroform 0.5 <0.05
TOC v bromoform -0.2 --
TOC v air temperature 0.4 --
TOC v water temperature 0.4 --
TOC v pH level -0.2 --
TOC v No. of people 0.5 p<0.05
TOC v TTHM 0.5 p<0.05
Chloroform v BDCM -0.2 --
Chloroform v CDBM -0.3 --
Chloroform v air temperature 0.3 --
Chloroform v water temperature 0.4 p<0.05
Chloroform v pH -0.1 --
Chloroform v number of people 0.7 p<0.01
Chloroform v TTHM 1.0 p<0.01
Bromoform v CDBM 0.5 p<0.05
Bromoform v BDCM 0.1 --
Bromoform v TTHM -0.4 p<0.05
BDCM v CDBM 0.9 p<0.01
TTHM v air temperature 0.4 --
TTHM v water temperature 0.5 p<0.01
TTHM v pH -0.1 --
TTHM v number of people 0.7 p<0.01

ACKNOWLEDGEMENTS

We are grateful to those staff in London swimming pools who kindly took part
in this project, thereby enabling us to complete the study, and the Thames
Water Quality Centre for the analysis of the samples.

Accepted 17 October 2001

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InfoTrac Web: Health Reference Center-Academic. Source: Occupational and Environmental Medicine, April 2002 v59 i4 p243(5). Title: Distribution and determinants of trihalomethane concentrations in indoor swimming pools. (Original Article).(Statistical Data Included)

InfoTrac Web: Health Reference Center-Academic.
Source: Occupational and Environmental Medicine, April 2002 v59 i4
p243(5).

Title: Distribution and determinants of trihalomethane concentrations in
indoor swimming pools. (Original Article).(Statistical Data
Included)