**3. Result and discussion**

The LOD of each compound for the analytes was determined as three times the standard deviation of seven independent replicate analyses. LOQs were determined as 3.3 times of LODs. Instrument detection limits ranged from 0.6 µgl-1 (DEHP) to 3.16 µgl-1 (4-NP) and the LOQs varied from 1.9 µgl-1 (DEHP) to 10.44 µgl-1 (4-NP) as presented in Table 4. The LODs and LOQs values are adequate for environmental monitoring of the target compounds and low enough compared to previous work on the analytes of interest (Fatoki and Noma, 2002; Yuan *et al*., 2002; Cortazar *et al*., 2005; Zhou *et al*., 2005; Kayali *et al*., 2006; Ling *et al*., 2007) taking into account the complexity of the samples and the low sample amounts used. For wastewater and river samples, the LODs achieved in the present work were at similar levels or lower than those obtained in previous studies with GC–MS (Yuan *et al*., 2002; Cortazar *et al*., 2005; Kayali *et al*., 2006). The chromatogram of the derivatized phenols and phthalate esters congeners are presented in Figure 3.

Health Risk Assessment of Plasticizer in Wastewater Effluents and Receiving Freshwater Systems 203

the only organic chemicals of those tested that could be included in the quantitative health

Phenol 11.14 151 208 93.43 ± 0.05 2.2 7.18 1.000 2-CP 15.21 185 149, 93 98.21 ± 4.38 1.9 6.34 0.988 DMP\* 15.27 163 77 83.72 ± 6.03 2.2 7.43 0.993

4-C,3MP 17.71 199 93 76.21 ± 5.28 2.96 9.77 0.989 DEP\* 18.38 149 177, 104, 77 98.46 ± 11.31 1.58 5.22 0.993 2,4-DCP 18.81 219 183, 125,93 94.1 ± 7.16 1.11 3.66 1.000

4-NP 20.74 196 150, 135 88.19 ± 10.29 3.16 10.44 0.999 2,4,6-TCP 20.76 255 217, 159, 93 73.21 ± 0.05 2.81 9.63 0.999 DBP\* 22.89 149 207 98.99 ± 8.27 0.9 2.9 0.978

PCP 24.58 323 93 92.64 ± 11.39 2.23 7.37 0.998 BBP\* 26.09 149 206, 91 97.43 ± 18.31 0.6 2.9 0.987 DEHP\* 27.35 149 279, 167 101.32 ± 0.21 0.6 1.9 0.989 DOP\* 29.01 149 279, 57 90.77 ± 5.39 1.41 4.65 0.988

Table 4. Retention time, target ion, limits of detection and quantification in GC-MS of the

sampling sites used in the primary screening for human health risk assessment.

The average concentrations detected in all the sample sites over the sampling period of a year was used as a most likely scenario to determine what risks (if any) were involved as a screening risk assessment. If a chemical was found to be responsible for risks considered by the US-EPA and WHO to be unacceptably high, a more detailed assessment for that chemical was investigated, making use of the spread of the data, averages, and identifying which sampling site was responsible for the highest concentrations detected. The following graphs (Figures 4 & 5) illustrates the average concentrations of the chemicals detected at the

DBP was found at highest concentrations in both river water samples and wastewater effluents, followed by nitro-phenol (NP) and DEP (Figures 4 & 5). Human dose-response data was available for DEHP and DBP to allow a quantitative health risk assessment to be performed (ATSDR, 1995; 2001; 2002). The results of the exposure calculations are given in the Table 5 and are presented as both Average Daily Dose (ADD) and Lifetime Average

SPE Recovery (%)

LOD (µgl-1)

<sup>105</sup>98.69 ± 8.43 1.4 4.78 0.987

136, 91 95.39 ± 11.68 1.36 4.47 1.000

<sup>137</sup>96.34 ± 2.93 1.63 5.36 0.986

179, 149 90.33 ± 6.18 1.48 4.87 0.976

LOQ (µgl-1)

Correlation Coeffient R2

Reference ion (m/z)

risk assessment.

2-M, 4,6-

Compound Retention

Time (min)

2,4-DMP 15.74 179 163, 149,

2-NP 19.15 196 180, 151,

2,4-DNP 23.39 241 225, 195,

DNP 24.29 255 239, 209

\*Compound not affected by MTBSTFA derivatization

Daily Dose (LADD) in mg/kg/d.

selected phenols and phthalates recoveries (n = 7).

Target ion (m/z)

Fig. 3. Chromatogram of derivatized phenols and phthalate esters.

Five point calibration curves were constructed using triplicate injections of the derivatized standard. The retention time, target ion monitored, and the SPE recovery of the selected phenols and phthalates are presented in Table 4. Analysis of the result demonstrated the concordance of the response with a linear model as shown in Table 4, where the regression coefficient ranges from 0.976 to 1.000. The method precision and accuracy were satisfactory. The detectable concentration range was from 2.5 to 1000 µgl-1. Due to non-availability of reference materials, the validation of the analytical method for extraction and elution was assessed through the recovery of standard mixtures of the target analytes in Milli-Q water. For the efficient quantification of the target compounds, analysis was performed within the linear portion of the calibration curve.

#### **3.1 Health risk assessment**

There are many associated adverse health effects if people are exposed to these chemical contaminants in excess doses. Where possible the study looked at whether people might be exposed to excessive concentrations through various pathways, such as if water were used for domestic purposes, if the water were used to irrigate vegetables, if fish living in the water were eaten on a regular basis, if the rivers were used for recreational swimming and lastly if meat were consumed from the area making use of the water. The classic example of a population that differs from the norm is subsistence fishers, who may consume as much as 10 times the amount of freshwater fish that most citizens do.

This population is of particular concern when evaluating surface water contamination in areas that are economically depressed or if the immune systems of the people in the area are compromised. The methodology used to asses this potential human health risk was that described by the US-EPA (1988, 1996) and the WHO (2002), making use of the risk assessment programme, Risk Assistant TM (Thistle Publishers, 1996). DEHP and DBP were


the only organic chemicals of those tested that could be included in the quantitative health risk assessment.

\*Compound not affected by MTBSTFA derivatization

202 Recent Advances in Plasticizers

Five point calibration curves were constructed using triplicate injections of the derivatized standard. The retention time, target ion monitored, and the SPE recovery of the selected phenols and phthalates are presented in Table 4. Analysis of the result demonstrated the concordance of the response with a linear model as shown in Table 4, where the regression coefficient ranges from 0.976 to 1.000. The method precision and accuracy were satisfactory. The detectable concentration range was from 2.5 to 1000 µgl-1. Due to non-availability of reference materials, the validation of the analytical method for extraction and elution was assessed through the recovery of standard mixtures of the target analytes in Milli-Q water. For the efficient quantification of the target compounds, analysis was performed within the

There are many associated adverse health effects if people are exposed to these chemical contaminants in excess doses. Where possible the study looked at whether people might be exposed to excessive concentrations through various pathways, such as if water were used for domestic purposes, if the water were used to irrigate vegetables, if fish living in the water were eaten on a regular basis, if the rivers were used for recreational swimming and lastly if meat were consumed from the area making use of the water. The classic example of a population that differs from the norm is subsistence fishers, who may consume as much as

This population is of particular concern when evaluating surface water contamination in areas that are economically depressed or if the immune systems of the people in the area are compromised. The methodology used to asses this potential human health risk was that described by the US-EPA (1988, 1996) and the WHO (2002), making use of the risk assessment programme, Risk Assistant TM (Thistle Publishers, 1996). DEHP and DBP were

Fig. 3. Chromatogram of derivatized phenols and phthalate esters.

10 times the amount of freshwater fish that most citizens do.

linear portion of the calibration curve.

**3.1 Health risk assessment** 

Table 4. Retention time, target ion, limits of detection and quantification in GC-MS of the selected phenols and phthalates recoveries (n = 7).

The average concentrations detected in all the sample sites over the sampling period of a year was used as a most likely scenario to determine what risks (if any) were involved as a screening risk assessment. If a chemical was found to be responsible for risks considered by the US-EPA and WHO to be unacceptably high, a more detailed assessment for that chemical was investigated, making use of the spread of the data, averages, and identifying which sampling site was responsible for the highest concentrations detected. The following graphs (Figures 4 & 5) illustrates the average concentrations of the chemicals detected at the sampling sites used in the primary screening for human health risk assessment.

DBP was found at highest concentrations in both river water samples and wastewater effluents, followed by nitro-phenol (NP) and DEP (Figures 4 & 5). Human dose-response data was available for DEHP and DBP to allow a quantitative health risk assessment to be performed (ATSDR, 1995; 2001; 2002). The results of the exposure calculations are given in the Table 5 and are presented as both Average Daily Dose (ADD) and Lifetime Average Daily Dose (LADD) in mg/kg/d.

Health Risk Assessment of Plasticizer in Wastewater Effluents and Receiving Freshwater Systems 205

Based on the exposure assumptions described in the section above, risks of developing cancer and toxic effects were calculated for the various phthalate chemicals where sufficient data was available. Most of the chemicals were found at concentrations to be below those where "unacceptable" risks, as defined by both the WHO and US-EPA, are anticipated. However, risks of developing cancer may be as high as 2 in one thousand resulting from exposure to DEHP (Figure 6) resulting predominantly from exposure through vegetables that have been irrigated with the contaminated water, and to a lesser extent, through the

DEHP was detected at high concentrations at Kirstenbosch, Kuils River, Mosselbank River and Vygekraal River. In general, river waters contained higher concentrations than treated effluents of the waste water treatment works (Figure 6). This risk would result if the water were used to irrigate vegetables or if fish grown in the water were consumed on a regular

Vygekraal River DEPH 0.02474 0.0106

Vygeraal Effluent DEHP 0.007983 0.0003421

Kuils River 1 DEHP <sup>0</sup> <sup>0</sup>

Kuils River (1) Effluent DEHP 0.007982 0.003421

Mosselbank River DEHP 0.06066 0.0206

Mosselbank Effluent DEHP 0.03233 0.01385

Diep River Effluent DEHP 0.003991 0.00171

Kuils River (2) DEHP 0.1014 0.0435

Kuils River (2) Effluent DEHP 0.1189 0.05097

Veldwachter River DEHP 0.04191 0.1796

Veldwachter Effluent DEHP 0.05827 0.02497

Kirstenbosch Stream DEHP 0.1278 0.1278

Vygekraal Effluent = Athlone WWTP effluent; Kuils River (1) Effluent = Bellville WWTP Effluent; Mosselbank Effluent = Kraaifontein WWTP Effluent; Kuils River (2) Effluent = Zandvliet WWTP Effluent Veldwachter Effluent = Stellenbosch WWTP Effluent; Kirstenbosch Stream = Control Site. Table 5. Predicted total average daily doses and lifetime average daily doses, based on

average concentrations of phthalates.

Diep River DEHP 0.003592 0.001539

**Site Chemical ADD (mg/kg/d) LADD (mg/kg/d)** 

DBP 0 0

DBP 0.003242 0.001389

DBP 0.3895 0.1708

DBP 0.4377 0.1876

DBP 0.3943 0.169

DBP 0.115 0.04927

DBP 0 0

DBP 0 0

DBP 0.4941 0.2118

DBP 0.1147 0.04914

DBP 0.6986 0.02497

DBP 0.471 0.2019

DBP 0 0

consumption of fish, grown in the contaminated water.

basis.

Fig. 4. Concentrations (µgl-1) of phthalate and phenolic congeners detected in river and WWTP effluents at different sites (excluding DBP).

Fig. 5. DBP concentrations (µgl-1) detected in effluent and river water samples at the different sites.

20<sup>62</sup>

1

0

46

Vygekraal Effluent

225

123

Vygekraal River

138

ug/l

20

0

87

Kuils River 1 Effluent

WWTP effluents at different sites (excluding DBP).

2836

2582

Kuils River river

745

Mosselbank River Effluent

Fig. 5. DBP concentrations (µgl-1) detected in effluent and river water samples at the

21

Vygekraal Effluent

ug/l

different sites.

0

Vygekraal River

Kuils River 1 Effluent

94

372

0

68

146

Kuils River river

111

81

32

0

Mosselbank River Effluent

12

152

15

0

Mosselbank river

DEHP DEP NP 2CP

2555

Mosselbank river

DBP

0

Diep River Effluent

0

Diep River river

743

Kuils River 2 Effluent

Kuils River river

Veltwachter Effluent

Veltwachter River

3202

3052

Fig. 4. Concentrations (µgl-1) of phthalate and phenolic congeners detected in river and

29

10

92

47

Diep River Effluent

9

0

60

Diep River river

0

269

298

161

93

Kuils River 2 Effluent

122

254

213

109

Kuils River river

63

146

23

0

Veltwachter Effluent

105

138

73

Veltwachter River

4527

0

Kirstenbosch River

110

747

763

13

17

Kirstenbosch River

110

Based on the exposure assumptions described in the section above, risks of developing cancer and toxic effects were calculated for the various phthalate chemicals where sufficient data was available. Most of the chemicals were found at concentrations to be below those where "unacceptable" risks, as defined by both the WHO and US-EPA, are anticipated. However, risks of developing cancer may be as high as 2 in one thousand resulting from exposure to DEHP (Figure 6) resulting predominantly from exposure through vegetables that have been irrigated with the contaminated water, and to a lesser extent, through the consumption of fish, grown in the contaminated water.

DEHP was detected at high concentrations at Kirstenbosch, Kuils River, Mosselbank River and Vygekraal River. In general, river waters contained higher concentrations than treated effluents of the waste water treatment works (Figure 6). This risk would result if the water were used to irrigate vegetables or if fish grown in the water were consumed on a regular basis.


Vygekraal Effluent = Athlone WWTP effluent; Kuils River (1) Effluent = Bellville WWTP Effluent; Mosselbank Effluent = Kraaifontein WWTP Effluent; Kuils River (2) Effluent = Zandvliet WWTP Effluent Veldwachter Effluent = Stellenbosch WWTP Effluent; Kirstenbosch Stream = Control Site.

Table 5. Predicted total average daily doses and lifetime average daily doses, based on average concentrations of phthalates.

Health Risk Assessment of Plasticizer in Wastewater Effluents and Receiving Freshwater Systems 207

This section examined whether possible human health effects might be anticipated based on chemical contaminants detected in wastewater effluents and in rivers throughout the Western Cape, South Africa. In order to determine whether this is possible, a human health risk assessment was conducted by modelling the chemical contaminant concentrations expected in vegetables, fruit, fish and meat based on levels detected in water. Trans-media calculations (water to fish; water to fruit and vegetables and water to meat) were conducted based on individual chemical parameters described in the earlier

The screening risk assessment identified the chemicals that could be responsible for adverse health effects if drinking the untreated water or eating fish , fruit, vegetables or meat , over a 30 year period were to occur. Although not present at the highest concentrations, the chemicals that were of principal concern were identified as DEHP and to a lesser degree, DBP and arsenic. The type of adverse effect that might result was also identified as predominantly carcinogenic, with possible reproductive system toxic effects being anticipated, as the predicted doses were well below those considered safe by the WHO and

sections.

US EPA.

Fig. 7. Hazard quotients for individual phthalates.

Fig. 6. Cancer risks from DEHP exposure.

Toxic risks could be anticipated resulting from exposure to both DEHP and DBP with individual exposure concentrations predicted at up to 14 times that considered to be safe for a lifetime exposure (Figure 7 & 8). However, the certainty of the reference dose, or the dose considered to be safe, has a safety factor of 100 built into it for both DEHP and DBP (ATSDR, 2002; and ATSDR, 2001 respectively). The safety factors built into the reference doses for DEHP and DBP are to allow for extrapolation from animals to humans (a factor of 10) and to allow for variability within humans (another factor of 10) (ATSDR 2001 & 2002). The predicted risks indicate that a possible risk exists and does not indicate a definite risk as the exposures are modelled and not based on actual measurements.

The driver of the human health risk was identified through this exercise. The chemicals responsible for the risks include DEHP and to a lesser extent, DBP (Figures 6 & 7). DEHP was found to be the major contributor of risk of developing cancer in this screening health risk assessment. The highest potential risks were observed at Kirstenbosch resulting from DEHP detected in the river water. The potential risk through the use of this water is if it were used to irrigate vegetables.

5.0E-05

Vygekraal Effluent

0.0E+00

5.0E-04

1.0E-03

1.5E-03

2.0E-03

2.5E-03

2.0E-04

Vygekraal River

Fig. 6. Cancer risks from DEHP exposure.

were used to irrigate vegetables.

Kuils River 1 Effluent

Kuils River river

exposures are modelled and not based on actual measurements.

2.0E-04

Mosselbank River Effluent

4.0E-04

Mosselbank river

2.0E-05

Diep River Effluent

DEHP

Toxic risks could be anticipated resulting from exposure to both DEHP and DBP with individual exposure concentrations predicted at up to 14 times that considered to be safe for a lifetime exposure (Figure 7 & 8). However, the certainty of the reference dose, or the dose considered to be safe, has a safety factor of 100 built into it for both DEHP and DBP (ATSDR, 2002; and ATSDR, 2001 respectively). The safety factors built into the reference doses for DEHP and DBP are to allow for extrapolation from animals to humans (a factor of 10) and to allow for variability within humans (another factor of 10) (ATSDR 2001 & 2002). The predicted risks indicate that a possible risk exists and does not indicate a definite risk as the

The driver of the human health risk was identified through this exercise. The chemicals responsible for the risks include DEHP and to a lesser extent, DBP (Figures 6 & 7). DEHP was found to be the major contributor of risk of developing cancer in this screening health risk assessment. The highest potential risks were observed at Kirstenbosch resulting from DEHP detected in the river water. The potential risk through the use of this water is if it

2.0E-05

Diep River river

7.0E-04

Kuils River 2 Effluent

6.0E-04

Kuils River river

3.0E-04

Veltwachter Effluent

3.0E-04

Veltwachter River

Kirstenbosch River

2.0E-03

1.0E-05

EPA recommended

This section examined whether possible human health effects might be anticipated based on chemical contaminants detected in wastewater effluents and in rivers throughout the Western Cape, South Africa. In order to determine whether this is possible, a human health risk assessment was conducted by modelling the chemical contaminant concentrations expected in vegetables, fruit, fish and meat based on levels detected in water. Trans-media calculations (water to fish; water to fruit and vegetables and water to meat) were conducted based on individual chemical parameters described in the earlier sections.

The screening risk assessment identified the chemicals that could be responsible for adverse health effects if drinking the untreated water or eating fish , fruit, vegetables or meat , over a 30 year period were to occur. Although not present at the highest concentrations, the chemicals that were of principal concern were identified as DEHP and to a lesser degree, DBP and arsenic. The type of adverse effect that might result was also identified as predominantly carcinogenic, with possible reproductive system toxic effects being anticipated, as the predicted doses were well below those considered safe by the WHO and US EPA.

Fig. 7. Hazard quotients for individual phthalates.

Health Risk Assessment of Plasticizer in Wastewater Effluents and Receiving Freshwater Systems 209

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Fig. 8. Hazard quotients for total phthalates.
