The occurrence of methyl, ethyl, propyl, and butyl parabens in the urban rivers and stormwaters of Sydney, Australia

Wendy A. Evans a, Peter J. Davies *b and Christopher McRae c
aMacquarie University, NSW 2109, Australia. E-mail:
bMacquarie University, NSW 2109, Australia. E-mail:; Tel: +61 2 98507220
cMacquarie University, NSW 2109, Australia. E-mail:

Received 15th October 2015 , Accepted 27th May 2016

First published on 8th June 2016

Parabens, commonly used preservatives, are emerging pollutants that are known to enter waterways through the wastewater system where they can pose a threat to aquatic organisms. Less is known about their presence and contribution to urban waterways in cities with separated stormwater and wastewater systems, such as Sydney, Australia. We measured the occurrence of methyl-(MeP), ethyl-(EtP), propyl-(PrP) and butyl-(BuP) parabens in urban river and stormwater samples across a range of land uses, using solid-phase microextraction with gas chromatography-mass spectrometry for the analysis. MeP in modified stormwater channels was more frequently detected and found at higher mean levels (6.29 μg L−1) than in urban rivers (3.62 μg L−1). Waterways in residential catchments had greater mean total paraben load (26.87 μg L−1) when compared to parkland catchments (12.71 μg L−1) and bushland catchments (2.10 μg L−1). EtP had the highest peak concentrations across the study area (max = 305.55 μg L−1) associated with industrial land uses and areas historically associated with poor water quality. The levels of EtP were relatively high when compared to international studies in cities with combined stormwater and wastewater systems. The results also suggest overflows from the sewer during heavy rain are likely not as significant when compared to the contribution from urban runoff. The study did not reveal the source of the EtP and further studies are recommended to identify this and the potential environmental impact.

Water impact

This is the first study describing the geographic distribution of four parabens in the urban waterways of Sydney. Unlike many studied cities, Sydney has separated stormwater and wastewater systems giving it international relevance. Differences in paraben concentrations were identified between stormwater, rivers, and in relation to land uses that have implications for urban water management and highlight areas for further investigation.

1.0 Introduction

Parabens are the alkyl esters of p-hydroxybenzoic acid. Common esters include methyl-(MeP), ethyl-(EtP), propyl-(PrP), and butyl-(BuP) parabens and their sodium salts.1 These compounds have been added as an antimicrobial and preservative agent since the 1920s in a wide range of personal care products (PCPs) such as shampoos, deodorants, shower gels, sunscreens, and cosmetics, but they are also found in pharmaceuticals, food, paper products, and packaging.2–8 Their popularity and wide spread use is largely due to their cost effectiveness, ease of use, and perceived overall safety.9–11

In 2004 Darbre, et al., identified a potential risk associated with parabens and human health due to their mild oestrogenic properties and presence in breast cancer tissue.12 While a causal link between breast cancer and parabens is still under investigation,13,14 Charles & Darbre (2013) identified the growth of breast cancer MCF-7 cells in vitro when found in combination with parabens.15 In 2011 Meeker, et al., reported a link with sperm damage in men.16 These studies have served as the catalyst for the European Union to place a limit on parabens in food products17 and Denmark to also limit parabens on the import, sale and use of in PCP and in products used by children under the age of three.18

Parabens have also been implicated in endocrine disruption in other organisms11,19 including adverse effects on the male reproductive system such as reduced sperm count in rodents20,21 and imposex and fertility problems in fish.22,23 Additionally Terasaki, et al. (2009) reported that parabens can be toxic to aquatic organisms such as daphnia.24 Toxicological research on acute and long term low-level exposure, however, is sparse. Although the oestrogenic activity of parabens is relatively weak when compared to that of the naturally occurring steroid and oestrogen hormone 17β-oestradiol,25 they also readily react with free chlorine in tap water, raw wastewater and where chlorine is used in water treatment.24,61–63 The resulting chlorinated by-products have shown higher acute toxicity responses in Daphnia,24 and this affect should be considered where parabens are entering the aquatic environment, although more study in this area is required.25

Parabens can enter the environment through a variety of means including via wastewater.4,26–32 They have also been detected in house dust,33,66 soil,34 rivers and lakes,26–29,31,32,35–43 and in marine sediments.44 The presence of parabens in surface waters has largely been attributed to leaks, overflows, and discharges of wastewater. Other sources include industrial discharges, leachate from landfill, and surface runoff. The extent of these pathways is yet to be fully described. Concentrations in surface waters are typically low and, as an emerging pollutant, significant research has been directed to extraction techniques.4,25,32,45

In this study the presence and concentration of MeP, EtP, PrP, and BuP are examined across urban waterways including rivers and stormwater systems in Sydney, Australia. Sydney is unique when compared to many international urban study areas in that the stormwater and wastewater systems are independent of each other.46 The study also aims to identify if there are correlations between the type and concentration of parabens related to land use and catchment area.

2.0 Materials and methods

2.1 Study area and site selection

The urban water environments and stormwater drainage systems within the Sydney metropolitan area were the focus of this study (Table 2, Appendix 1). Sydney has a separated wastewater and stormwater system:46,47 the stormwater system is designed to convey urban runoff and drains to local waterways and the ocean. Stormwater assets in Sydney are owned and managed primarily by local government. The wastewater system is owned and operated by Sydney Water Corporation and treats more than 1.3 billion liters of wastewater each day.48 The wastewater system has over 24[thin space (1/6-em)]000 km of wastewater pipes with effluent treated via inland and mostly coastal sewerage treatment plants.49 Some mixing of the stormwater and wastewater systems occurs via infiltration and exfiltration from the extensive pipe network and directly into and from waterways. Designed wastewater overflows are discharged into urban waterways during periods of heavy rain and form part of the environmental pollution licence Sydney Water Corporation has with the NSW Government.50

Sample sites were selected to cover catchments with various land uses, as delineated geographically by the Australian Bureau of Statistics (refer to Tables 2 and 3 for a summary of sample sites and their land use types).51 These uses comprised of: parkland, including bushland, reserves, and national parks; residential, including areas of low to high density housing; commercial uses including CBDs, educational facilities, and shopping complexes; industrial sites that included factories associated with manufacturing (incorporating sites with bio-retention systems and rain gardens), waste management services (landfills), processing, and construction; and post-treated sewage treatment plant (STP) discharge.

Sampling sites were also classified by the physical type. These included: stormwater, which incorporated locations from, or directly downstream of pipes, drains, and channels specifically designed to convey excess urban surface runoff associated with rainfall; rivers, which ranged from natural unmodified bushland catchments to highly urban rivers with modified banks; and sites upstream and downstream from STP discharge points. Only post treated urban wastewater was sampled as access to STP inlet waste water was not possible.

2.2 Sample collection

Water samples (n = 72) were collected between July and September 2014. Samples were taken from waterway edges/banks as far into the flow as possible, from bridges, directly from stormwater discharge points and storage tanks. The sample collection method followed that used by Peng (2008).29 Samples were collected in clean (non-sterilised, so as to reduce potential contamination from detergents) 40 mL amber glass bottles to reduce the likelihood of photodegradation.64 Sampling occurred from banks or bridges at a water depth of <1 m as parabens tend to concentrate in the top of the water column.29 Before sample collection, each bottle was pre-rinsed with sample water three times. However, unlike Peng (2008), microbial biodegradation suppressant, sodium azide, was not added to the samples as any present parabens were unlikely to undergo biodegradation due to their own antimicrobial properties.9 Samples were stored at 4 °C and the sample storage and hold times followed EPA (2007) guidelines52 for the testing of personal care products in water.

34 samples were taken from rivers, 34 from stormwater systems and 4 from post-treated STP discharge points. Sampling from tidal rivers was undertaken during the ebbing period in order to reduce the dilution effect of tidal influx. The coordinates of each sample site were recorded using GPS.

2.3 Materials

Four esters of 4-hydroxybenzoic acid were used in this study. Methyl paraben (C8H8O3) analytical standard and ethyl (C9H10O3), propyl (C10H12O3) and butyl (C11H14O3) paraben secondary standards, were purchased from Sigma-Aldrich (Sydney, NSW, Australia). Methanol (CH₃OH) and ethyl acetate (C4H8O2) were from Honeywell, sodium chloride (NaCl) was from Univar. Glassware, including unsterilized 60 mL amber glass headspace injector vials and un-bonded PTFE/Silicone Septa, were purchased from Velocity Scientific (Perth, WA, Australia). SPME holder and fibers coated with polyacrylate (PA; 85 μm film thickness) were obtained from Supelco (via Sigma-Aldrich, Sydney, Australia). Prior to use the fibers were prepared as per the manufacturer's instructions. Standard solutions (between 2–50 μg L−1) were prepared in a mixture of methanol and RO water and stored at 4 °C in a fridge.

The GPS (Garmin) was set to WGS 84 map datum and data was removed using MapSource software version 6.16.3. All spatial analysis was undertaken using ArcGIS 10.2 software. The map layers (shape files) included the Sydney Special (hydrography and framework) from Geoscience Australia (2004),53 and NSW Land Use Mesh Blocks from the Australian Bureau of Statistics (2011).51

2.4 Extraction and analysis

The pH of each sample was recorded using a Hanna pH 211 microprocessor to ensure the samples were within the operating range of the SPME fibers. The extraction technique used was modeled on that used by Canosa et al. (2006). Final micro-extractions were accomplished using a manual solid-phase microextraction (SPME) holder and PA fibers in 40 mL volume glass vessels containing a magnetic Teflon coated stir bar and filled with 10 mL of water sample. Sodium chloride content was added at a rate of 150 mg mL−1 to assist diffusion of the analytes to the fibre.4 However, unlike the method derived by Canosa et al. (2006), derivatisation for detection enhancement using MTBSTFA was not undertaken as the tert-butyldimethylsilyl derivative would likely decrease the volatility of the analytes and increase the risk of error, especially in this case where derivatisation would have been completed on fibre. Prior to the analysis of samples, the GC-MS was evaluated using a Grob Test Mix (Restek Cat.#: 35[thin space (1/6-em)]000). The test mix showed excellent peak shape (asymmetry was <1.2 on all peaks of interest) and recoveries for the alcohol and phenol components of the mix, including for chlorophenol, which is much more acidic than the paraben analytes, and no loss or tailing was observed for this compound. For these reasons derivatisation was deemed unnecessary.

SPME extractions were carried out manually in the direct sampling mode, at room temperature (21.7 °C, 70% humidity), using a PA fiber. During extraction the fibers were fully submerged in the samples. After an exposure period of 10 minutes, which was determined by the authors to be the optimum exposure time for analytes to be absorbed across the PA fiber, the SPME fiber was retracted into the needle of the holder syringe, water drops attached to the metallic needle were removed using a soft paper tissue.

The analysis technique developed by the authors was undertaken using a gas chromatography-mass spectrometry (GC-MS) on a Shimadzu GC-17A gas chromatograph fitted with a Restek Rtx-5Sil capillary column (30 m × 0.25 mm, 0.25 μm film thickness) interfaced to a Shimadzu QP-5000 mass selective detector. A constant carrier (99.999% helium – velocity of 40 cm s−1) was used, the injector was held at 270 °C, and the transfer line held at 300 °C.

Samples were introduced by thermal desorption into a split/splitless injector fitted with a SPME specific injector liner (0.75 mm × 5 mm × 95 mm). The injector was operated in splitless mode with a sampling time of 5 minutes. The mass spectrometer was run in selected ion monitoring (SIM) mode monitoring ions m/z 121 and m/z 149 over a 0.2 second sampling interval. Ion m/z 149 was used to monitor the presence of phthalates which elute in the same region as parabens. Ion m/z 121 was used for both qualitative and quantitative purposes and m/z 149 was used to qualitatively identify phthalates. Identification of the paraben analytes was confirmed by co-elution with the internal surrogates (monitored at m/z 127), thus allowing for the monitoring of two ions.

The oven program used was 70 °C for 5 minutes, then ramped at 30 °C per minute to 140 °C, and then ramped at 10 °C per minute to 220 °C before a final ramp at 30 °C per minute to 300 °C and held for 5 minutes. Total run time was 23 minutes. Fibers were desorbed between runs.

Quantification was accomplished using an internal standard method, using a 13C labelled analogue containing methyl 4-hydroxybenzoate-(ring-13C6), ethyl 4-hydroxybenzoate-(ring-13C6), propyl 4-hydroxybenzoate-(ring-13C6), and butyl 4-hydroxybenzoate-(ring-13C6), as an internal surrogate. Calibration was achieved against absolute standard solutions of the analytes in RO water. A 6-point calibration curve (2.00–100.0 μg L−1) was created for each paraben ester. The detection limits (LOD) of the method ranged from 1.00–2.00 μg L−1 for the analytes. The calibration showed a linear regression with correlation coefficients (R2) ranging from 0.946 to 0.996. The repeatability (RSD, n = 3) was between 6.07–12.0% (see Table 1).

Table 1 Linearity, repeatability and quantification limits of the GC-MS method using 10 μg L−1 spiked RO water using 3 replicates expressed as parts per billion and test of method on three spiked samples
Linearity, repeatability and quantification limits of the method – 10 μg L−1
Compound MeP EtP PrP BuP
Spiked RO samples have been prepared using standards made up to 10, 20 and 100 parts per billion (μg L−1). Target and result shown.
Correlation coefficient (R2) 0.947 0.993 0.996 0.985
Repeatability (RSD%) 12.0 6.57 6.07 11.8
Limit of detection (μg L−1) 1.00 2.00 1.00 1.00
Spiked sample 1 (10 μg L−1) 9.3 8.7 8.8 8.0
Spiked sample 2 (20 μg L−1) 20.8 21.5 21.4 22.3
Spiked sample 3 (100 μg L−1) 99.9 99.8 99.8 99.7

2.5 QA/QC

Extraction blanks (10 mL of RO water) and spiked blanks (between 2.00–10 μg L−1 of each analyte in 10 mL of RO water) were included in runs of samples. RO water was tested as a sample before use and no parabens were found within the detection limits of the GC-MS. The GC septum was changed every 20 injections to reduce the chance of leaks and fibers were desorbed between runs. A number of samples (n = 5) were re-processed and no significant difference was found between the runs. To reduce the likelihood of sample contamination, personal care items (e.g. moisturizers and detergents that contained parabens) were avoided during sample collection, preparation, and analysis.

3.0 Results

At least two parabens were found at all sites with the exception of a bushland catchment in the parkland land use category which was used as a reference point. Levels of MeP across the 72 sample sites ranged between 4.62 μg L−1 and 13.78 μg L−1 with a mean of 5.11 μg L−1 and a median of 5.75 μg L−1 (Table 2). MeP was the least frequently detected analyte (n = 50) (Table 3). EtP ranged between 2.75 μg L−1 and 305.55 μg L−1 with a mean of 13.81 μg L−1 and a median of 5.17 μg L−1. EtP was the second most frequently detected paraben found at 68 sites and included the 9 highest readings of parabens at any of the sites (between 13.78–305.55 μg L−1) which were associated with industrial areas. PrP (n = 59) ranged from 2.42 μg L−1 to 8.29 μg L−1 with a mean of 2.79 μg L−1 and a median of 2.87 μg L−1 and was persistent at low levels in the sample area. BuP was found at levels between 3.86 μg L−1 and 8.47 μg L−1 with a mean of 4.31 μg L−1 and a median of 4.36 μg L−1 and was detected the most frequently (n = 69).
Table 2 Sample site information including GPS coordinates, sample type, land use, pH, and SPME/GC-MS analysis results given as parts per billion (μg L−1) of samples from Sydney's urban waterways
Site Latitude Longitude Type pH Land use Detected parabens μg L−1
MeP EtP PrP BuP Total load
n.d. Not detected at sample site.
001 −33.7874 151.1116 Stormwater 6.13 Residential 7.31 5.65 5.61 4.41 22.99
002 −33.7941 151.1098 River 6.34 Residential 6.38 n.d. 5.60 4.34 16.31
003 −33.7228 151.1461 Stormwater 7.35 Residential 7.66 5.98 n.d. 4.42 18.06
004 −33.8917 151.2819 Stormwater 7.95 Residential 7.95 5.72 5.59 4.40 23.67
005 −33.8964 151.2740 Stormwater 7.25 Residential 7.81 n.d. 5.70 4.39 17.91
006 −33.8981 151.2756 Stormwater 7.16 Residential 7.86 5.74 5.60 4.41 23.61
007 −33.8992 151.2725 Stormwater 8.02 Residential 7.43 5.76 5.62 4.36 23.17
008 −33.8971 151.0853 Stormwater 8.16 Industrial 9.52 58.50 5.20 5.11 78.33
009 −33.9043 151.1104 Stormwater 9.27 Residential 10.82 54.57 6.22 5.53 77.15
010 −33.9142 151.1237 River 7.82 Residential 12.51 35.17 5.12 5.92 58.72
011 −33.9230 151.1427 River 7.40 Residential 9.51 27.28 3.83 5.20 45.81
012 −33.9279 151.1589 River 6.70 Industrial 7.14 14.07 3.19 4.50 28.90
013 −33.8891 151.0770 Stormwater 7.50 Industrial n.d. 6.32 2.69 4.04 13.05
014 −33.8995 151.0786 Stormwater 8.00 Industrial n.d. 7.82 2.60 4.06 14.48
015 −33.9152 151.1204 River 9.67 Industrial 6.60 8.33 2.87 4.40 22.20
016 −33.9262 151.0971 Stormwater 8.00 Industrial 5.78 5.16 2.42 4.10 17.45
017 −33.9382 151.1028 Stormwater 9.67 Industrial n.d. 3.66 2.46 3.89 10.01
018a −33.9297 151.1382 River 8.03 Industrial n.d. 5.18 8.29 4.36 17.83
018b −33.9297 151.1382 River 7.96 Industrial 6.17 4.52 2.90 4.13 17.71
019 −33.8400 151.1436 River 7.63 Residential n.d. 5.57 3.01 4.20 12.77
020 −33.8325 151.1344 River 8.44 Residential n.d. 5.98 2.75 4.31 13.04
021 −33.8209 151.0903 River 7.91 Residential n.d. 6.93 2.68 8.47 18.07
022 −33.8149 151.0881 Stormwater 8.75 Parkland n.d. 4.61 2.42 4.08 11.11
023 −33.8158 151.0783 River 7.81 Parkland n.d. 4.95 2.76 4.19 11.90
024 −33.8170 151.0788 River 6.88 Parkland n.d. 4.70 2.45 4.19 11.34
025 −33.8140 151.0312 River 7.07 Industrial n.d. 4.89 2.58 3.94 11.42
026 −33.8176 151.0408 River 7.23 Commercial n.d. 5.24 2.75 4.18 12.17
027 −33.8177 151.0409 River 7.86 Commercial n.d. 4.38 n.d. 3.89 8.27
028 −33.8108 151.0037 Stormwater 7.87 Commercial 7.75 3.51 2.55 4.01 17.82
029 −33.8431 151.0164 River 7.44 Industrial n.d. 4.30 3.21 4.59 12.11
030 −33.8323 151.0163 Stormwater 7.17 Commercial 6.69 3.87 3.42 4.89 18.87
031 −33.8356 151.0231 Stormwater 7.32 Industrial 5.68 305.55 3.14 4.53 318.89
032 −33.8248 151.0517 River 7.56 Commercial 4.62 13.78 3.12 4.88 26.40
033a −33.9640 151.2535 Stormwater 8.47 Residential 13.76 4.78 2.65 4.58 25.77
033b −33.9640 151.2535 Stormwater 8.30 Residential 9.68 4.56 3.09 4.69 22.01
034a −33.9652 151.2518 Stormwater 7.92 Residential 6.93 6.44 3.44 5.30 22.10
034b −33.9652 151.2518 Stormwater 8.00 Residential 11.76 5.86 3.32 5.26 26.20
035 −33.9463 151.2582 Stormwater 7.66 Residential 5.49 4.96 3.18 4.68 18.30
036 −33.9538 151.2577 Stormwater 7.05 Residential 7.56 3.04 2.59 4.12 17.31
037 −33.9193 151.2596 Stormwater 7.60 Residential 5.57 6.26 3.23 5.23 20.29
038 −33.6070 150.8252 River 7.83 Residential n.d. 4.06 2.91 4.57 11.54
039 −33.6066 150.8250 Stormwater 5.79 Residential 13.78 5.15 3.72 5.43 28.08
040 −33.5999 150.8334 STP discharge 7.15 STP 12.28 4.95 3.15 4.69 25.07
041 −33.5767 150.7101 River 6.90 Commercial 7.93 6.29 3.15 5.09 22.46
042 −33.5749 150.7165 STP discharge 6.98 STP 4.83 4.76 2.91 4.82 17.32
043 −33.5727 150.7312 STP discharge 7.08 STP 6.41 4.23 2.64 4.21 17.49
044 −33.7025 151.0805 River 7.95 Parkland n.d. 4.54 2.74 4.63 11.91
045 −33.7028 151.0802 River 7.87 Parkland n.d. 5.45 3.04 4.64 13.14
046 −33.7011 151.0809 Stormwater 7.79 Parkland n.d. 5.19 2.68 4.32 12.19
047 −33.7010 151.0808 STP discharge 7.67 STP 6.93 4.88 2.78 4.42 19.01
048 −33.7912 151.1159 Stormwater 7.59 Residential 6.20 3.87 2.51 4.10 16.67
049 −33.7689 151.1227 River 7.90 Parkland 8.50 4.94 3.06 4.46 20.97
050 −33.7699 151.1239 Stormwater 7.80 Residential n.d. 3.63 n.d. 4.00 7.64
051 −33.7698 151.1219 River 7.71 Parkland 5.37 5.53 3.09 4.61 18.59
052 −33.7651 151.1319 River 7.56 Residential n.d. 5.94 n.d. 4.25 10.19
053 −33.7926 151.1570 River 7.34 Parkland 5.73 3.41 n.d. 3.97 13.11
054 −33.8011 151.1439 River 7.06 Parkland 5.55 6.32 2.86 4.33 19.07
055 −33.6967 151.1118 River 7.00 Industrial 8.10 5.31 2.92 4.43 20.75
056 −33.6224 151.1509 Stormwater 7.20 Residential 5.08 4.26 n.d. 3.95 13.29
057 −33.7199 151.0826 River 7.25 Industrial 4.79 3.68 2.87 3.97 15.31
058 −33.7638 151.0890 Stormwater 7.25 Residential 8.12 4.27 n.d. 4.36 16.75
059 −33.7595 151.1015 Stormwater 7.26 Residential 6.02 3.42 n.d. 4.27 13.71
060a −33.7840 151.0851 Stormwater 7.36 Residential 5.17 3.04 n.d. n.d. 8.21
060b −33.7840 151.0851 Stormwater 7.49 Residential 5.27 n.d. n.d. 3.86 9.13
061a −33.7341 151.0873 Stormwater 7.34 Residential 6.44 6.10 2.91 4.69 20.14
061b −33.7341 151.0873 Stormwater 7.58 Residential 4.91 169.19 2.89 4.31 181.31
062 −33.6415 151.1357 River 7.33 Industrial 6.45 16.38 2.64 4.17 x29.64
063 −33.7715 151.1104 River 7.15 Commercial 5.09 2.75 n.d. n.d. 7.84
064a −33.6988 151.2374 River 7.00 Landfill 7.04 7.85 2.67 4.12 21.68
064b −33.6988 151.2374 River 7.26 Landfill 5.84 6.25 2.87 3.92 18.88
065 −33.7015 151.2379 River 7.56 Parkland n.d. 5.29 n.d. 3.87 9.16
066 −33.7073 151.2314 River 6.04 Parkland n.d. n.d. n.d. n.d. n.d.

Table 3 A summary of the detection frequencies of MeP, EtP, PrP and BuP across sites within stormwater and river water samples as well as by land use type
Detection frequencies (n) of four parabens according to sample type and land use
Sample type MeP EtP PrP BuP
Stormwater (n = 34) 28 32 27 33
River water (n = 34) 18 32 28 32
Land use type
Commercial (n = 7) 5 7 5 6
Industrial (n = 15) 9 15 15 15
Parkland (n = 14) 6 13 11 13
Residential (n = 32) 26 29 24 31
STP (n = 4) 4 4 4 4
Total (n = 72) 50 68 59 69

The Cooks River in the inner west region of Sydney accounted for five of the 10 most contaminated sites, which was unsurprising given the river's association with poor water quality.54 The two most contaminated sites of significance were site 031 Duck River Auburn and site 061b the Dawson Avenue raingarden in Thornleigh (Table 2). The Duck River site is downstream of an industrial area that also includes a waste transfer station. The Dawson Avenue raingarden drains a small retail shopping complex in a suburban catchment.

A comparison of the summarized results of this study with a random sample of the international published literature is presented in Table 4. Generally the concentrations of parabens found in this study are higher. This is particularly relevant when comparing concentrations of parabens in urban rivers and more urbanised catchments.

Table 4 Detected values from a random sample of international paraben studies (μg L−1) including mean data from all water samples in this study for comparison
Comparison of results to international studies
Study Year Country Waterway Type MeP EtP PrP BuP
n.d.: Not detected – under detection limits of the method n.a.: Not analysed * Denotes samples of influent and effluent from the same wastewater treatment site (a).
Mean results from this Sydney study 2014 Australia River Urban/industrial 3.63 7.33 2.70 4.26
2014 Australia Stormwater Urban/industrial 6.29 21.37 2.87 4.35
2014 Australia Effluent Urban 7.61 4.70 2.87 4.54
Leusch, et al.43 2013 Australia Influent Urban n.a. n.a. 0.011 n.a.
Peng, et al.29 2008 China River Urban 1.062 n.a. 3.142 n.d.
Peng, et al.29 2008 China River Urban 0.213 n.a. 0.693 n.d.
Terasaki, et al.57 2012 Japan River Urban 0.0037 n.d. 0.022 0.012
Gonzalez-Marino, et al.65 2009 Spain River Urban 0.0034 0.0030 0.069 0.007
Gonzalez-Marino, et al.65 2009 Spain River Urban 0.009 0.0012 0.0059 0.001
Villaverde-de-saa, et al.55 2010 Spain River Urban 0.054 0.029 0.105 0.0064
Ramírez, et al.56 2012 Spain River Urban 0.042 0.0011 n.d. n.d.
Canosa, et al.4 2006 Spain Sewer Urban/medical 1.48 0.10 1.22 0.019
Canosa, et al.4 2006 Spain Influent (a)* Urban 2.92 0.21 0.81 0.086
Canosa, et al.4 2006 Spain Effluent (a)* Urban n.d. n.d. n.d. n.d.
Canosa, et al.4 2006 Spain Influent (b)* Urban 0.43 0.052 0.23 0.020
Canosa, et al.4 2006 Spain Effluent (b)* Urban n.d. n.d. 0.064 n.d.
Lee, et al.26 2005 Canada Influent (c)* Urban/industrial 1.47 0.27 2.43 0.26
Lee, et al.26 2005 Canada Effluent (c)* Urban/industrial 0.04 <0.01 0.04 <0.01
Lee, et al.26 2005 Canada Influent (d)* Urban/industrial 0.63 0.12 0.86 0.12
Lee, et al.26 2005 Canada Effluent (d)* Urban/industrial 0.02 <0.01 <0.01 <0.01
Villaverde-de-saa, et al.55 2010 Spain Influent Urban 6.81 0.48 1.227 0.088
Ramírez, et al.56 2012 Spain Influent Urban 0.696 0.048 0.0053 0.052
Ramírez, et al.56 2012 Spain Influent Industrial 14.243 5.927 23.593 0.681
Gonzalez-Marino, et al.25 2011 Spain Influent Urban 4.20 0.880 1.40 0.014
Terasaki, et al.57 2012 Japan Influent Urban 2.40 0.57 2.60 4.45

3.1 Statistical analysis

Data was analyzed according to sample type (river/stormwater) and the land use categories mentioned in Table 3 using one-way ANOVAs with Welch's Correction for variance in MiniTab Version 17. Two-sample t-tests were then conducted on certain populations using MiniTab and MS Excel 365 for post hoc analysis.
3.1.1 Stormwater vs. river water. A one way ANOVA identified significant differences between the concentrations of the tested parabens in both stormwater and river water samples (p < 0.001). In the stormwater samples t-tests showed that BuP (M = 4.35, SD = 0.898) was found at higher concentrations than PrP (M = 2.87, SD = 1.87); t(47) = 4.17, p < 0.001 and that MeP (M = 6.29, SD = 3.69) was at greater concentrations than both PrP; t(48) = −4.84, p < 0.001 and BuP; t(36) = 2.99, p = 0.005. In river water samples EtP (M = 7.33, SD = 6.97): t(36) = −3.76, p = 0.001, and BuP (M = 4.26, SD = 1.35); t(63) = 4.21, p < 0.001, were significantly higher than PrP (M = 2.7, SD = 1.67). Additional two sample t-tests showed that concentrations of MeP in stormwater samples (M = 6.29, SD = 3.69) were significantly higher than the levels found in river water (M = 3.62, SD = 3.74); t(66) = 2.96, p = 0.004.

Concentrations of MeP are not only higher in stormwater than in river water, but they also occur more frequently (see Table 3). In stormwater samples MeP is likely to be in greater concentrations than BuP and PrP, and levels of BuP are also likely to be higher than PrP, while in river water samples both EtP and BuP are likely to be present at higher levels than PrP. These results also show a difference in paraben distribution between river and stormwater samples particularly in relation to MeP and EtP (Fig. 1).

image file: c5ew00240k-f1.tif
Fig. 1 Comparison of mean concentrations of parabens by sample type (μg L−1) with SE error bars.
3.1.2 Differences between land use categories. The total mean detected concentrations of all four parabens across land use types within Sydney's urban setting identified in this study are shown in Fig. 2. The mean total detected loads were: industrial (n = 15) 41.9 μg L−1, residential (n = 32) 26.9 μg L−1, STP (n = 4) 19.7 μg L−1, commercial (n = 7) 16.3 μg L−1, and parkland (n = 14) 13.79 μg L−1. These results imply that industrial sites contain the greatest concentration of parabens, which is a trend also identified by Ramírez (2012).
image file: c5ew00240k-f2.tif
Fig. 2 Comparison of mean concentrations of parabens by land use (μg L−1) with SE error bars.

A one way ANOVA (p = 0.042) identified differences in the total paraben concentration between residential and parkland land uses. post hoc t-tests showed that residential samples (M = 26.87, SD = 31.6) had higher concentrations of parabens when compared to parkland (M = 12.71, SD = 5.42) land use types; t(35) = 2.44, p = 0.020. Additionally a one way ANOVA (p = 0.031) and further t-tests showed that the concentrations of MeP in the samples from residential areas (M = 6.47, SD = 3.95) were significantly higher than those found in parkland (M = 2.10, SD = 3.20); t(42) = 3.42, p = 0.001. These results show that residential waterways tested have greater concentrations of MeP, as well as a greater total concentration of parabens than those in parkland catchment areas.

Within parkland land uses a one way ANOVA (p = 0.001) and post hoc two-sample t-tests indicated that concentrations of BuP (M = 3.94, SD = 1.27) were higher than PrP (M = 2.09, SD 1.28); t(21) = −3.56, p = 0.002, and that EtP (M = 4.58, SD 1.6) was higher than PrP (M = 2.09, SD = 1.28); t(20) = 4.2, p < 0.001. Within residential land use categories, a one way ANOVA (p < 0.001) followed by two sample t-tests showed levels of BuP (M = 4.56, SD 1.19) to be greater than PrP (M = 2.93, SD = 2.05); t(49) = 3.90, p < 0.001 and that MeP (M = 6.47, SD = 3.95), was higher than both PrP (M = 2.93, SD = 2.05); t(46) = 4.50, p < 0.001, and BuP (M = 4.56, SD 1.19); t(36) = 2.61, p = 0.013. These results found that within parkland land use areas EtP and BuP are both at greater concentrations than PrP. Within residential land use areas, MeP not EtP, is found at greater levels than BuP and PrP. The statistically significant differences in the distribution of MeP, EtP, PrP and BuP within Sydney's residential and parkland waters may point to multiple pathways for which parabens are entering the urban environment that are dependent on land use.

4.0 Discussion

The principal aim of this pilot study was to characterise the presence of parabens in urban waterways across Sydney. The results show that at least two of the four parabens (BuP, PrP, and/or EtP and/or MeP) are present across all sites and all land use types with the exception of internally drained bushland (site 066 that served as a reference location). The study reported comparatively high concentrations of parabens, particularly EtP, across the urban waterways of Sydney. These findings were higher when compared to urban waterway studies from other cities.

The higher concentration of EtP found in many of the urban locations in this study, relative to the other parabens, could be explained by a number of reasons. The high variability in paraben concentration across the study may suggest the need for more samples across the selected land use types, although the number of samples (72) is relatively high compared to other studies. Seasonal variation related to recent weather conditions can influence the amount of exfiltration from the sewerage system and therefor the composition of parabens in urban waterways. As sampling was undertaken in dry conditions, MeP related to PCP in the wastewater stream may have been under represented.

The urban drainage system (such as materials used in the drainage system) or practices by the community and industry may contribute to the higher proportion and concentration of EtP. The contributing factor leading to the presence of EtP, in particular, is unknown and requires additional research.

The analysis techniques, sample collection, storage and processing methods used in this study differed from other studies. For these reasons, additional study on the relative proportion and concentration of parabens across a range of urban land uses is recommended. Furthermore, repeat sampling of sites and examination of samples using an independent analytical approach is suggested.

Sydney has a separated sewer and stormwater system in contrast to the combined sewer/stormwater systems that exist in many other countries.46 This may account for a difference in the concentrations and relative presence of the four parabens studied when compared to international studies (Table 4) although further comparative study would be required to validate this assumption.

Based on previous research it was expected that MeP would be the most dominant paraben as it is most frequently used in PCPs.9 This was not the case. Across the study area MeP occurred less frequently and generally at much lower concentrations when compared to international sewer influent results (Table 4). This may reflect the shorter half-life of MeP when compared to other parabens,25 photodegradation64 of MeP in the environment or in sample (although care was taken to reduce the likelihood of this occurring), or that exfiltration from the sewer to stormwater and local waterways is not occurring at levels anticipated and/or contributing to total load of parabens linked to urban runoff.

Sampling up- and down-stream of the North Richmond (sites 042 and 043) and West Hornsby (sites 045 to 047) sewerage treatment plants (STPs) reported overall levels of parabens generally higher upstream (that is influenced by runoff) than below the discharge point. The exception was MeP which was lower upstream (and this would be expected given the association with MeP with PCPs). Without testing influent and determining the effectiveness of the STP in removing parabens, the reasons for the lower concentrations are unclear and may simply relate to the impact of dilution of parabens in the stream from the wastewater discharge. Both STPs are small scale tertiary treatment systems with North Richmond discharging approximately 0.9 ML per day and West Hornsby 11.9 ML per day (Sydney Water 2014a).49

The analysis identified statistically significant correlations between land use types and paraben concentrations. This study found that there was a significantly greater concentration of MeP as well as overall total paraben load in residential catchments when compared to catchments dominated by parkland, bushland, national parks and reserves. It is likely that sewage infiltration in the residential areas is a contributing factor to the total paraben load found in urban waterways, although it is not the only factor.

The highest concentration of parabens was reported at the Duck River site (031) a tributary of the Parramatta River draining an industrial area. The Cooks River, widely known in Sydney as being polluted58–60 reported the five of the top 10 highest parabens readings. The peak level of parabens along the Cooks River occurred at Ford Park (site 008) that drains an industrial area. A similar pattern of paraben concentration was also found along the Parramatta River with the peak concentrations occurring around Silverwater, a former industrial area. Ordinarily runoff from industrial premises is drained to the sewer via a trade waste agreement and not discharged to the stormwater system. The results may suggest illegal discharges, poor site management or the historical release of chemicals containing parabens that is transported during surface flow.

A high concentration of EtP was also found in the rain garden treating a small commercial catchment (061b). This could be the result of surface processes, the leaching of a product linked to the rain garden or an anomalous result. From a water sensitive urban design perspective there is need to identify the source and if the rain garden or biofiltration system would be able to capture and remove this pollutant.

5.0 Conclusions

The concentrations of parabens reported in this study are higher than that reported by the Australian study by Leusch, et al. (2013) and other international studies on urban waterways.43 The concentration of EtP is of particular interest as it frequently occurred at higher than median levels reported in all sewerage influent studies. The source of EtP is unknown. Significant statistical correlations between paraben concentrations were detected when comparing residential versus parkland. The differences between paraben concentrations in river and stormwater samples also highlight the need for further study in this area.

As a study of an emergent pollutant, the results identify that catchment processes in the urban area of Sydney are contributing to paraben concentrations often over and above what would be expected from leaks from the sewer. Higher results were associated with some industrial land uses however this was not statistically significant. While sewerage may contribute to part of the total concentration of parabens in urban waterways, the relatively high levels of EtP and lower levels and detection rates of MeP suggest other processes are important and worthy of additional enquiry.


Bryan Gilfedder and Dominic May for assistance in the field. Hornsby Shire Council for their assistance with stormwater sampling.


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Electronic supplementary information (ESI) available. See DOI: 10.1039/c5ew00240k

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