Annual report of the UNU Project in Vietnam, 2001

I. INTRODUCTION

Phthalates used in modern commerce are extremely common. One of their primary uses is as plasticizers in flexible polyvinyl chloride (PVC) products such as blood bags and children's toys, etc.. They are also used as fixatives, detergents, lubricating oils, and solvents. As a result of these diverse uses, phthalates are found in many consumer products, such as cosmetics, as well as in applications, such as wood finishes, that inevitably create opportunities for human exposure. Moreover, phthalates which occupies 67% of final product weight (O. Hutzinger, 1991), recently have been demonstrated to have weak estrogenic activity and thus can alter the estrogen level in hormone system of human being as well as animal resulting in serious health problems like cancer induction, reproductive and development impairment.   

In Vietnam, the use of phthalate has been being increasing since early 1990s together with development of plastic industry. However, there has been still no any due attention given toward its possible effects to environment contamination and human exposure. In addition, discharge of used plastic products containing phthalates is with only little management that makes presence of this compound ubiquitous in environment.     

For the above concerns and in the frame of the UNU project "Environmental Monitoring and Governance EDC Pollution in the East Coastal Hydrosphere" in Vietnam,  we have established the first dealing with the contamination of phthalates in aquatic environment under the specific condition in Vietnam. This research was conducted in three sites, including Red river (Hanoi city), its estuary (Balat, Thaibinh province), and Tamgiang-Cauhai-Langco lagoon (Thua Thien Hue province). The samplings were carried out two times during the year of 2000 and 2001 with surface water were collected for analysis of the following target compounds: DEP (Di-ethyl phthalate), DBP (Di n-butyl phthalate), DEHP (Di 2-ethyl hexyl phthalate) and DEHA (Di 2-ethyl hexyl adipate)

For continuous monitoring of alkylphenol, bisphenol-A and organochlorine compounds, surface water samples were also collected at the same three sites as presented in the 2001 report. This analysis is to assess the current pollution status and to evaluate time-trend variation of such compounds.

II. SAMPLING PROCEDURES

2.1. Selection of location

Water samples, including seawater and river water (for Red river) were collected in both rainy and dry season during year 2000 and 2001 except Red river and Balat estuary in dry season.

Because the levels of the monitored organochlorines compounds from the last study were constant between the forms of tide (see annual report year 2000), water samples taken in these events were mainly evaluated for seasonal variation.  Tab.A.1 and Tab.A.2 and Tab.A.3 (Appendix A) indicate more information related to the sampling conditions in Tamgiang-Cauhai-Langco lagoon, Red river and Balat estuary, respectively. Sampling time is given in table 2.1.

Table 2.1. Sampling time and location of the collected samples

Location	Sampling time	Chemicals analyzed
Red river	Jul. 2000 (Rainy season)	Phthalate, Bisphenol-A, alkylphenols, Organochlorines.
	Jan. 2001 (Dry season)	Phthalate, Bisphenol-A, alkylphenols, Organochlorines
Balat Estuary (sea water)	Jul. 2000 (Rainy season)	Phthalate, Bisphenol-A, alkylphenols, Organochlorines
	Jan. 2001 (Dry season)	Phthalate, Bisphenol-A, alkylphenols, Organochlorines
TamGiang lagoon	Aug. 2000 (Dry season)	Phthalate, Bisphenol-A, alkylphenols, Organochlorines
	Jan. 2001 (Rainy season)	Phthalate, Bisphenol-A, alkylphenols, Organochlorines

(Phthalate: the target compound of research 2001)

Water samples were collected in the surface layer (20 cm to 30 cm depth). They were contained in 2 liters glass bottles, immediately stored in the icebox and transported in less than 3 days to the laboratory where they would be kept in refrigerator until analysis.

Three sampling sites in this study are same as the sites selected for our previous study in 1999 (Vietnam annual report of UNU project, 1999). Our target is to continuously monitor the concentrations of the interested pollutants in those three areas so that we can evaluate their time-trend and seasonal variations. Details of sampling sites are showed in fig.2.1

2.2. Sampling sites description

The Red river is the most important river in Northern Vietnam that build up a delta spreading over an area of 2146 sq km with population around 2,736,400 people and providing largest rice production in the North. Hanoi, capital city of Vietnam and Thaibinh province are both located along Red river, Hanoi is in the middle and Thaibinh is in the downstream of this river.  Both cities are known as biggest rice producing provinces in the North. However, together with development of agriculture, many environmental problems became also concerned aspects because a large amount of pesticides and herbicides have been being used every year to protect crops from pest and weeds. In addition, many industrial centers in the Red river delta such as Hanoi, VietTri, ThaiBinh, HaiPhong are believed to daily discharge their wastewater containing toxic pollutants to aquatic environment through small rivers and creeks. These toxic substances all come to Red river, the largest inland reservoir. This problem is therefore, posing a potential danger for environment and human health of the population living along the river.

Located about 650 km in the south of Hanoi city and with population of 1,045,130 (1999), Thua Thien-Hue is an important province well known for its tourism activities and traditional, fine agricultural products. Belonging to this province, Tamgiang-Cauhai-Langco lagoon system spreads over 23,650 hectares, with 70 km of length along the northwest coast. These lagoons are recognized as one of the biggest ones in Asia and play a very important role to remain diversity of ecosystem in large coastal area.  The lagoon is also a reservoir of water from five regional rivers including Huong river, Olau river, Bo river, Truoi river, Loinong river and Cauhai river.

2.3. Sample preparation and analysis

The preparation of water samples for analysis of organochlorine compounds, bisphenol-A, alkylphenols and phthalates were performed according to the suggested standard procedures of UNU (Anonymous, 2001).

For phthalates analysis in each water samples, take 100 mL of water samples into a 100 mL volumetric flask. Add 5 mL n-hexane into this. Then further add 100 mL of 100 ppm IS1, IS2 and surrogate compound in this again. Shake the volumetric flask for 1 minute and let it staying for about 5 minute and finally pick up n-hexane layer and enter to vial of 1ml. Inject 2 mL to GC/MS.

Analysis of organochlorine compounds, bisphenol-A, alkylphenols has carried out by application of the combined procedure, which was suggested in annual report of the UNU project in Vietnam, 2001. Fig. 2.2 shows the flow chart for preparation of water samples for analyzing simultaneously alkylphenolic, bisphenol-A and organochlorine compounds.

Target compounds were quantified by a GCMS-QP500 (Shimadzu). The GC column employed was DB-1 fused silica capillary (0.32 mm x 30 m) coated with 100% dimethylpolysiloxane at 0.25 mm film thickness. The quantification was conducted by calculating the ratio of peak area of the sample with peak area of internal standard to the corresponding ratio of peak area of standard with peak area of internal standard. Appendix B reports the detail conditions for setting up GC/MS for qualitative and quantitative analysis of bisphenol-A and alkylphenols. Because the conditions for setting up GC/MS for analysis of organochlorine compounds were thoroughly described in the previous annual report, it was not repeatedly described in this report.

Figure 2.1. Combined analytical produce for simultaneous analyzing of alkylphenolic, bisphenol-A and organochlorines compounds in water

III. RESULTS AND DISCUSSIONS

3.1. Obtained results of water samples

3.1.1 Phthalates

Concentration of four compounds diethylphthalates (DEP), di- n- butylphthalates (DBP), di- 2- ethylhexyladiphates (DEHA) and di- 2- ethylhexylphthalates (DEHP) in water samples has been collected from three chosen areas are shown in Table 3.1. Detailed levels of these target compounds in each water sample are illustrated in the Table C.1, Table C.2, and Table C.3 (Appendix C).

Table 3.1. Concentrations of DEP, DBP, DEHA, DEHP (ng.L^-1) in collected water samples

No	Compounds	Red river RS (n=5)	Balat estuary RS (n=15)	Tamgiang- Cauhai- Langco lagoon
				DS (n=24)	RS (n=24)
1	DEP	< 2 (< 2)	< 2 (< 2)	4.9 (< 2- 17.6)	3.7 (< 2  - 6)
2	DBP	4.6 (< 1.2- 8.3)	3.9 (< 1.2 - 16.9)	2.3 (< 1.2- 9.2)	2.1 (< 1.2- 8)
3	DEHA	< 4 (< 4)	5.5 (< 4  - 7.2)	6.5 (< 4- 13.8)	6.3 (< 4  - 28.8)
4	DEHP	18.3 (8.8- 25.6)	17.2 (2.3- 36.2)	18.8 (< 1.1  - 78)	14.3 (2- 32)
5	S Phthalates	22.9 (0.01- 25.6)	21.1 (<  - 36.2)	26 (<  - 78)	20.1 (<   - 32)
	Figures in parentheses ( ) indicate the  range      RS: rainy season;     DS: dry season   ;      n: amounts of analyzed samples
	S Phthalates = DEP+DBP+DEHP.

As being seen in table 3.1, in rainy season, level of DEP was lower than detection limit (2 ng.L^-1) in both sites at Red river and Balat estuary. However, in Tamgiang- Cauhai- Langco lagoon, DEP concentration was found at average concentration of 3.7 ng.L^-1 in rainy season and also in this site, the concentration was 4.9 ng.L^-1 in dry season.

DBP on the other hand was determined in al three sites with only low concentrations: 4.6, 3.9, and 2.1 ng.L^-1 in Red river, Balat estuary and Tamgiang- Cauhai- Langco lagoon respectively, in the rainy season. In particular, DBP was found with 2.3 ng.L^-1  in Tamgiang- Cauhai- Langco lagoon, in the dry season.

The third compound, DEHA was lower than detection limit (4 ng.L^-1) in Red river