**2.7 Quality assurance and quality control (QA/QC) for GC-MS**

Spiked procedural blanks, solvent blanks and control samples were included in each batch of analyses. Blanks and controls were treated similarly as the samples and analyzed after every sample injection. A calibration standard solution of 50 µgl-l was injected in duplicate to monitor the instrumental sensitivity and reproducibility every time before sample analyses.

#### **2.8 Health risk assessment**

A human health risk assessment was conducted to provide an indication of whether the organic compounds or heavy metals detected in the water samples tested may cause adverse health effects to human. The methodology used to assess this potential human health risk was that described by US-EPA (1988, 1996) and the WHO (2002). The exposures considered in the assessment include:


Human exposure to toxic effects are expressed in terms of average daily dose (ADD) which is the amount of substance taken into the body on daily basis during the exposure period calculated

$$ADD = \left(\mathbf{C}\_{medium} \ge IR \ge ED \ge F\_c\right) / \BOV \ge AT \text{ (mg/kg\,d)}\tag{5}$$

where:

198 Recent Advances in Plasticizers

spectrometer

temperature

Inlet temperature

Transfer line Scan mode (m/Z)

ionization, 70 ev

230 oC

260 oC

280 oC 50-450

(0.25 µm film thickness) Ion source Electron impact

Gas chromatography Mass

Capillary Column DB-5MS, 30 m x 0.25 mm i.d.

Injector parameters 1 µl splitless, injection

Table 2. Gas Chromatography and Mass Spectrometer Parameters.

Sampling started in April 2010 and ended in March 2011.

**2.7 Quality assurance and quality control (QA/QC) for GC-MS** 

a. Ingestion through drinking of final effluents or river water,

c. Irrigating farm lands with final effluent or river water,

b. Dermal absorption due to daily washing/bathing in the river water,

Oven temperature

analyses.

**2.8 Health risk assessment** 

considered in the assessment include:

d. If fish from these areas is consumed.

**2.6 Seasonal sampling protocol** 

GC-MS Agillent 6890N 5975

Carrier gas Helium, purity: 99.999 % Ion source

temperature 260 oC

80 oC (1 min) -5 oC min-1 150 oC held for 1 min, then to 280 oC at 12 oC (7 min), carrier gas flow rate: 1.0 mlmin-1 Post run temperature: 300 oC (2 min)

Water samples for organic compounds analysis were collected from the wastewater treatment plants and rivers on quarterly basis. This was to observe the possible impact of seasonal variation on organic compounds in wastewater treatment plants and possible impact this could have on the concentration of congeners in the freshwater systems.

Spiked procedural blanks, solvent blanks and control samples were included in each batch of analyses. Blanks and controls were treated similarly as the samples and analyzed after every sample injection. A calibration standard solution of 50 µgl-l was injected in duplicate to monitor the instrumental sensitivity and reproducibility every time before sample

A human health risk assessment was conducted to provide an indication of whether the organic compounds or heavy metals detected in the water samples tested may cause adverse health effects to human. The methodology used to assess this potential human health risk was that described by US-EPA (1988, 1996) and the WHO (2002). The exposures *ADD* = average daily dose *Cmedium* = concentration in the contaminated water *IR* = daily intake rate *ED* = exposure duration *Fc*, = the fraction contaminated *BW* = body weight *AT* = lifetime averaging time

For risk of carcinogens for exposures that last less than lifetime, the dose is adjusted using the formula:

$$\text{LADD} = \text{ADD} \times \text{(ED/L/ft)} \tag{6}$$

where: *Lft* is lifetime
