Quantitative Microbial Risk Assessment

Case Study-Yamuna River

In the International Perspectives on Quantitative Microbial Risk Assessment-III At IIPH Hyderabad

IndiaFriday, 27.03.2015

Team Members:Neethu Puthumadathil

Hima WaniNikita ChadhaDr. Vanisree

Shailender Kumar

Introduction

• River Yamuna, with a total length of around 1370 km is the largest tributary of the Ganges.

• Its source is at Yamunotri in the Uttarakhand Himalaya regions.

• It used to be a clear blue river but since the past few decades it has turned into one of the most polluted river in the world, especially Delhi, which dumps about 57% of its waste into the river (Central Pollution Control Board, 2005)

Representation of the SCenario

Problem Statement:

To estimate bacterial risks of infection annually for villagers of village “DD” using all

possible combinations of given activities in a year.

Objectives :

•Assessment of risk with respect to “de minimus” or more substantial

• Groups of people at most risk and activities associated.

• Rank exposure in decreasing order of their annual risks of infection and risk

management approaches for minimizing these exposure risks.

• To assess reduction in fecal coliforms in order to meet the USEPA allowable

annual risks of microbial infection guideline for recreational water contact.

• To check uncertainties in analysis.

Hazard • Identified biological hazard Shigella spp. and

Vibrio. Spp.• Characteristics

• Gram-negative bacteria with a curved-rod shape (comma shape) 

• It is anaerobic type of microorganism found in saltwater, and do not form spores.

• Cause acute diarrhoeal disease

Vibrio Spp.

• Gram-negative, facultative anaerobic, nonspore-forming, nonmotile, rod-shaped bacteria.

• cause serious intestinal diseases, including bacillary dysentery

Shigella spp.

Source: Guidelines for Drinking Water, WHO (2011)

EXPOSURE PARAMETER

SourceRoute of exposure

Exposure mediaFrequency of exposure

DurationExposed Populations

Scene 1Stream AA

Fecal – Oral Route

Drinking water 365 days

Adults, Children, Pregnant women

Scene 2Stream AA

Fecal – Oral Route

Drinking water32 times

(4 months)

45 mins

(for 1 event)

Adults and Children

DOSE RESPONSE

FC in stream AA

Pathogen to FC ratio

Number of Pathogens Concentration

Ingestion(per event)

MPN/100 ml MPN/100 ml MPN/100 ml MPN/ml 1.50E+07 Shigella Children 5.49E-07 8.24E+00 0.08235 37Shigella adult 0.08235 16Vibrio children 3.29E-06 4.93E+01 0.49335 37Vibrio adult 0.49335 16

DoseNumber of days of exposure α N50 P(daily) infection

P(annually) infection

3.04695 32 2.65E-01 1.48E+03 6.80E-03 0.196247188

1.3176 32 2.65E-01 1.48E+03 2.97E-03 0.09077451218.253

95 322.50E-

012.43E+0

2 1.72E-01 0.997611045

7.8936 322.50E-

012.43E+0

2 9.45E-02 0.958225953

Pant, A. and Mittal, A. K. (2007) Monitoring of pathogenicity of effluents from the UASB based sewage treatment plant. Environ Monit Assess. 133:43-51.

Exposure Factor Handbook, 2011

DOSE RESPONSE (Point Estimation) Shigella spp. Vibrio spp.

Sub-Population Drinking Recreational Activities Sub-

Population Drinking Recreational Activities

P(d) P(y) P(d) P(y) P(d) P(y) P(d) P(y)

Child 0.065638 1 0.006804 0.196247 Child 0.479342 1 0.171926 0.997611

Pregnant woman 0.113811 1 NA NA Pregnant

woman 0.556901 1 NA NA

Adult 0.135943 1 0.002969 0.090775 Adult 0.582022 1 0.094469 0.958226

Probability of infection (daily and annually)

Ingestion Parameters for Monte Carlo

Input Parameter Mean STDFecal Coliform(FC) –

MPN/100 ml 1.50E+07 8.00E+02Ingestion Volume –

ml/event 37 26

Example for Recreational Activity in Children

Monte Carlo Analysis

RISK ESTIMATION

Monte Carlo P annual (Recreational activity) P annual (drinking water)

Children Adult Adult Child Pregnant woman

Shigella Vibrio Shigella Vibrio Shigella Vibrio Shigella Vibrio Shigella Vibrio

mean 0.209848 0.993201 0.106854 0.925442 1 1 0.99985 1 0.999998 1

median 0.195849 0.997588 0.090551 0.95794 1 1 1 1 1 1

5th percentile 0.102447 0.970573 0.036228 0.748462 1 1 0.999965 1 1 1

Confidence interval 0.314854 0.999834 0.189348 0.997169 1 1 1 1 1 1

95th percentile 0.364634 0.99994 0.227941 0.998878 1 1 1 1 1 1

99th percentile 0.468347 0.999992 0.324546 0.999865 1 1 1 1 1 1

RISK CHARACTERIZATION

Recreational activity Drinking water

Children Adult Adult Child Pregnant woman

Shigella Vibrio Shigella Vibrio Shigella Vibrio Shigella Vibrio Shigella Vibrio

Risk v/s Concentration 0.04576 0.027921 -0.03347 -0.009 0.009635 - 0.016872 - 0.044285 -

Risk v/s Ingestion 0.993032 0.53566 0.995552 0.619868 0.062095 - 0.077462 - 0.070817 -

Correlation of the annual Probability of Risk v/s Input Parameters

RISK COMMUNICATION

• Survey Percentage of people boiling or filtering the drinking water

Homes with sanitation facilityNeed for sanitation and clean drinking water

• Awareness Radio and TV announcements

Gram Panchayat meetings

Drinking Water

Pathogen Population Maximum allowable concentration Reduction required

Shigella Children 1.39E+05 1.08E+02

Adults 5.53E+04 2.71E+02

Pregnant 7.05E+04 2.13E+02

Vibrio Children 3.05E+04 4.92E+02

Adults 1.21E+04 1.24E+03

Pregnant 1.54E+03 9.74E+03

Recreational Activity

Shigella Children 1.78E+07 8.43E-01

Adults 4.11E+07 3.65E-01

Vibrio Children 9.02E+07 1.66E-01

Adults 3.90E+05 3.85E+01

RISK MANAGEMENT

RISK MANAGEMENT

• Awareness• FC is 100 fold higher than the maximal

allowable concentration of FC in Drinking water

• Need for need for treatment of stream water AA

• Establishment of treatment plant/primary solution

REFERENCES

• Microbial fact sheets, Chapter 11, Guidelines on quality of Drinking water, WHO, 2011

• Pant, A. and Mittal, A. K. (2007) Monitoring of pathogenicity of effluents from the UASB based sewage treatment plant. Environ Monit Assess. 133:43-51.

• EPA. 2011. EPA Exposure Factors Handbook, available online at:http://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=236252

THANK YOU