Presentation by Pham Duc P, Nguyen-Viet H, Tu Vu-Van, Khuong Nguyen-Cong, Nga Do-Thu and Zinsstag J at the Ecohealth 2012 conference held at Kunming, China on 15-18 October 2012

1. Interdisciplinary approach to environmental
health research related to wastewater and
excreta use in agriculture in Vietnam
Pham Duc P, Nguyen-Viet H, Tu Vu-Van, Khuong Nguyen-
Cong, Nga Do-Thu and Zinsstag J.
Hanoi School of Public Health (HSPH)

2. Contents
• Introduction
• Aim & objectives
• Study sites
• Health impacts: Epidemiology and Microbial risk assessment
• Environmental impacts: Material Flow Analysis
• Social aspects
• Conclusions

3. Introduction
Advantages
• In Vietnam, the use of wastewater & excreta in
agriculture has a long history
• Many benefits: reliable nutrients and water
source; reduce chemical fertilizer
Risks
• Wastewater & excreta contain variety of
pathogens (viruses, bacteria, protozoa &
parasites)
• Enteric pathogens is a fundamental consideration
of public health (diarrhoea, parasitic diseases)

4. Analysis of interrelations between environmental sanitation systems, health status and well-being
Health status
(Water and Sanitation)
Exposure to pathogens (viruses, bacteria,
protozoa, helminths)
Health related and help seeking behavior
QMRA
EPI
Health risks-impacts,
Affected population
Dynamic interactions
Physical environment Social, cultural and
between systems and economic environment
interventions
Food chain Structure of society
Excreta, Wastewater, Water Empowerment
Nutrients: N, P Economic status
Chemical pollutants
SSA
MFA
Ecological risks and use Vulnerability, resilience
of resources and equity patterns
Critical control points: comprehensive biomedical, epidemiological, ecological, social,
cultural and economic assessment
Interventions (biomedical, systems, engineering, behavioral or in combination):
Nguyen-Viet et al. 2009. EcoHealth Efficacy, effectiveness and equity studies measured in relation to risks

5. Study aim & objectives
Aim: To enhance our understanding on health & environmental impacts &
social aspects of wastewater and excreta use in agriculture by combining
health & environmental & social assessment approaches.
Objectives:
1. To assess health risks for helminth infections and diarrhoea among people
working and living in agricultural settings, where wastewater and excreta
are intensively used.
2. To analyse nutrient fluxes of nitrogen and phosphorus in an environmental
sanitation and agricultural system, by using material flow analysis (MFA).
3. To understand the people’s awareness & motivations of hygiene as a risk
to human health related to excreta and wastewater management.

6. Study sites (2008-2010)
Vietnam: Area: 331,000 km2
Population: 87 million (MOH, 2011)
Rural population: 74%
Population below poverty line: 29%
Hoang Tay & Nhat Tan communes

7. Situation of the study sites
Raise animals: 84% Households: 4,300 Single vault latrine: 56%
Inhabitants: 16,200
Use of excreta as fertilizer: 51%
Local ponds: 10% Use of Nhue River water: 93%

8. The environmental sanitation and agricultural systems
Water Household (wastes)
source
Excreta/ Solid Landfill
Waste
water Manures wastes
Sanitation Composting
Food
(5)
Sewages (2)
Livestock
Pond (3) Irrigation system
Crop
(4)
Pumping stations
Nhue River (1)
Wastewater from Hanoi City (households, industries, hospitals,..)

9. I. Health risk assessment
• Epidemiological studies (EPI)
– Cross-sectional study (Prevalence and risk factors for helminth
infections)
– Cohort and nested case-control studies (Incidence rates & risk factors
of diarhoea)
• Quantitative microbial risk assessment (QMRA)
– Hazard identification, dose-response analysis, exposure assessment
and risk characterization
– Estimated risk of diarrhoea caused by E. coli, Giardia and
Cryptosporidium at the specific exposure points

10. II. Material flow analysis
Literature Review
Development of model
Define a preliminary MFA system
with main processes and mass flows
Conduct field survey to collect primary,
secondary data
Calibration of model
Adapt MFA model
Conduct uncertainty analysis (sensitivity,
plausibility assessments)
Yes
Model validated successfully
Develop scenario of target site and Development of scenario
propose mitigation measure

11. III. Social aspects
• In-depth interviews, participatory observations, focus
group discussions
• Protection Motivation Theory (Roger, 1983)
Threat appraisal
- Vulnerability
- Fear
- Severity
Motivation
- Response efficacy
- Self efficacy Intention
Habit
Coping appraisal Action

12. Results – Health risks
• Prevalence: any helminths (47%), A. lumbricoides (24%), T. trichiura
(40%), hookworm (2%).
• Incidence rate of diarrhoea: 0.25-0.32 episodes per person-year (pppy)
• Estimated annual risks of diarrhoea:
– Giardia: 0.13 - 0.50 pppy
– Cryptosporidium: 0 - 0.15 pppy
– E.coli: 0 - 0.24 pppy
• Risk factors for helminth infections and diarrhoea
– Direct contact with water from Nhue river (OR: 2.4; 95% CI: 1.2 – 4.7)
– Handling human excreta in field work (OR: 5.4; 95% CI: 1.4 – 21.1)
– Not use of protective measures at work (OR: 6.9; 95% CI: 3.5 – 13.9)
– Never handwashing with soap (OR: 3.3; 95% CI: 1.8 – 6.3)
– Drinking rainwater (OR: 5.4; 95% CI: 2.4 – 12.1)

13. Results – Environmental impacts
Nitrogen and Phosphorus fluxes in wastewater in different scenarios
199
200
180
160
140 Year 2008
Tonnes per year
115
120 109 Year 2020
100
100
Year 2020 with improved on-site
80 71 sanitation
Year 2020 with reuse wastewater
60
35 32 35
40
20
0
Nitrogen Phosphorus
Wastewater to drainage system

14. Results – Social aspects
• People perceive wastewater as smelly and black in colour, whose
contact can cause skin problems & diarrhoea.
• Correlation between motivation and hygiene practice
0.35
Fear of disease
Hygiene
0.11 practice
0.32
Self-efficacy
0.30 Motivation
Response-efficacy
Hygiene
0.30 0.19 practice in
Severity relation to
wastewater use
Vulnerability
0.18

15. Conclusions
• Health risk assessment
– Exposed to wastewater and excreta increase risks for helminth infections and
diarrhoea
– Basic personal hygiene measures and food hygiene increase to protect against
diarrhoea
– Annual risks of diarrhoea exceeded the acceptable risk levels set by the WHO (at
least 3 times)
• Environmental impacts
– Uncontrolled on-site sanitation system discharge large amount of nutrients into the
environment (drainage system & surface water)
– If nutrient management not improved, levels of nutrients due to wastewater, faecal
sludge, and organic solid waste will double until 2020.
• Social aspects
– Raising farmers’ awareness of health risks associated with wastewater reuse and
ability to cope with these risks enhance safe handling and health improvement
practices.
• QMRA, MFA and PMT methods could use the same platform, which is an
environmental and agriculture system, to introduce a combined environmental,
health risk & social aspects.

16. Acknowledgements

17. Thank you for your attention!!!