Lead exposure in a municipal water system: City of Ottawa Case … Workshop/05 Ottawa_case... ·...

September 16th, 2016

Lead exposure in a municipal water

system: City of Ottawa Case Study

ODWAC presentation

Ian Douglas, P.Eng. Penny Wilson Andy Campbell

Case study: Ottawa

1) typical lead profile at tap

2) household water use patterns

3) geographic distribution of pre-1955 homes

4) how many children are affected? • pH corrosion control • phosphate treatment • no corrosion control

5) Relative lead contributions: air, food, dust, water

6) How effective is phosphate treatment

7) lead removal by in-home filters

8) how effective is tap flushing

Lead Copper

Lead Lead

Partial LSL Full LSL

~15,000 15,000

MOECC lead results – histogram of winter vs. summer

0

20

40

60

80

100

120

< 1

.0

1 -

2

2 -

3

3 -

4

4 -

5

5 -

6

6 -

7

7 -

8

8 -

9

9 -

10

10

- 1

1

11

- 1

2

12

- 1

3

13

- 1

4

14

- 1

5

15

- 1

6

16

- 1

7

17

- 1

8

18

- 1

9

19

- 2

0

> 2

0

Nu

mb

er o

f R

esu

lts

Lead conc. (ppb)

L1 & L2 samples from MOECC in-home lead testing (n=1500 homes)

10 ppb

Factors affecting tap water lead exposure ?

pH temperature length of service pipe diameter of pipe galvanic corrosion flowrate stagnation period tap flushing water chemistry corrosion control? household plumbing type of faucet (eg. brass) time of consumption household water use patterns amount consumed particulate vs. dissolved

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

Flowing 1st Litre 2nd Litre 3rd Litre 4th Litre 5th Litre 6th Litre 7th Litre 8th Litre

Average lead concentrations at kitchen tap for house with Partial & Full LSL (flowing & 30-min stagnation; summer; n=10 homes)

Full LSL Partial LSL

Lead

co

nc

(pp

b)

How does lead concentration vary at the tap ?

Water use patterns in a “typical” family home ?

1-week flow surveillance at 2 homes with young families

flowrate monitored every minute x 7 days

average duration between water use events = 34 min

for <4 minute water takings, average volume = 3.3 Litres

average # of water taking “events” = 54 per day

average duration of water use = 204 min/day


dishwasher

laundry?


leaking

toilet?

Theoretical Lead Solubility vs. pH

Ottawa X

Treatment options – pilot & full-scale trials

1. Current strategy (control)

pH 9.2

2. Elevated pH

pH 9.4 – 9.8

3. Phosphate

pH 7.5

1 mg/L as P

3 –8 ppb

2– 5 ppb

1–2 ppb

Summer

2016 trial

pH 9.4

Distribution of pre-1960 homes (LSL) City of Ottawa

Potential lead exposure pattern in municipal water supply City of Ottawa (population 875,000; 10.8% <9 yrs old) Corrosion control with pH=9.2 (summer)

Older homes

(Pb)

[1875 – 1955]

Post-war

(Cu)

[1955 – 1980]

15%

30%

55%

New home

(Cu)

[1980 – 2015]

Full LSL

“BAD”

Full LSL

normal

10%

90%

8.2 ppb

0.4 ppb

0.4 ppb

1.9 ppb

3.8 ppb

52,000

# of children [Pb]tap

28,300

710

6,380

7,090

Potential lead exposure pattern in municipal water supply City of Ottawa (population 875,000; 10.8% <9 yrs old) Corrosion control with pH=9.2 (summer)

Older homes

(Pb)

[1875 – 1955]

Post-war

(Cu)

[1955 – 1980]

15%

30%

55%

New home

(Cu)

[1980 – 2015]

50%

50%

Full LSL

(Pb/Pb)

Partial LSL

(Pb/Cu)

Full LSL

“BAD”

Full LSL

normal

10%

90%

8.2 ppb

0.4 ppb

0.4 ppb

1.9 ppb

3.8 ppb

52,000

# of children [Pb]tap

28,300

710

6,380

7,090

Estimated tap water lead exposure for various house types (weighted mean [Pb] based on fraction consumed – assume no in-home filter)

Lead concentrations - estimated based on sampling 2007 - 2016 (n=1100) & pilot plant testing

I. pH corrosion control (pH=9.2)

Water portionLead conc.

(µg/L)

fraction

consumed

Lead conc.

(µg/L)

fraction

consumed

Lead conc.

(µg/L)

fraction

consumed

Lead conc.

(µg/L)

fraction

consumed

fully flushed (>2min) 2.5 0.50 4.9 0.50 1.5 0.60 0.3 0.60

30min stagnation in plumbing 3.0 0.25 7.8 0.25 2.0 0.30 0.6 0.40

30min stagnation in LSL (L3/L4) 7.0 0.25 15.0 0.25 3.8 0.10 0.3 0.00

Pb conc: 3.8 8.2 1.9 0.4

II. PO4 corrosion control (pH=7.5)


(µg/L)

fraction

consumed

Lead conc.

(µg/L)

fraction

consumed

Lead conc.

(µg/L)

fraction

consumed

Lead conc.

(µg/L)

fraction

consumed




Pb conc: 1.4 1.9 0.6 0.2

III. no corrosion control (pH=7.5)


(µg/L)

fraction

consumed

Lead conc.

(µg/L)

fraction

consumed

Lead conc.

(µg/L)

fraction

consumed

Lead conc.

(µg/L)

fraction

consumed




Pb conc: 19.8 27.7 10.9 0.4

Old house full LSL Old house full LSL"BAD" Old house partial LSL New house (Cu)

Old house full LSL Old house partial LSL New house (Cu)Old house full LSL"BAD"

Old house full LSL Old house full LSL"BAD" Old house partial LSL New house (Cu)

Potential lead exposure pattern in municipal water supply City of Ottawa (population 875,000; 10.8% <9 yrs old)

Corrosion control with pH=9.2 (summer)

Older homes

(Pb)

[1875 – 1955]

Post-war

(Cu)

[1955 – 1980]

15%

30%

55%

New home

(Cu)

[1980 – 2015]

50%

50%

Full LSL

(Pb/Pb)

Partial LSL

(Pb/Cu)

Full LSL

“BAD”

Full LSL

normal

10%

90%

8.2 ppb

0.4 ppb

0.4 ppb

1.9 ppb

3.8 ppb

(52,000)

# of children

[Pb]tap

(28,300)

(710)

(6,380)

(7,090)

Expected BLL increase as a function of tap water lead concentration, given typical Canadian levels of Pb in dust/food/air (IEUBK modelling by E.Deshommes, Ecole Polyt.)


Corrosion control with pH=9.2 (summer)

Older homes

(Pb)

[1875 – 1955]

Post-war

(Cu)

[1955 – 1980]

15%

30%

55%

New home

(Cu)

[1980 – 2015]

50%

50%

Full LSL

(Pb/Pb)

Partial LSL

(Pb/Cu)

Full LSL

“BAD”

Full LSL

normal

10%

90%

8.2 ppb

0.4 ppb

0.4 ppb

1.9 ppb

3.8 ppb

(52,000)

# of children

[Pb]tap

(28,300)

(710)

(6,380)

(7,090)

+1.3 µg/dL

+0.6 µg/dL

+0.3 µg/dL

+0.07 µg/dL

+0.07 µg/dL

+BLL


Corrosion control w. phosphate at pH=7.5 (summer)

Older homes

(Pb)

[1875 – 1955]

Post-war

(Cu)

[1955 – 1980]

15%

30%

55%

New home

(Cu)

[1980 – 2015]

50%

50%

Full LSL

(Pb/Pb)

Partial LSL

(Pb/Cu)

Full LSL

“BAD”

Full LSL

normal

10%

90%

1.9 ppb

0.2 ppb

0.2 ppb

0.6 ppb

1.4 ppb

(52,000)

# of children

[Pb]tap

(28,300)

(710)

(6,380)

(7,090)

+0.3 µg/dL

+0.2 µg/dL

+0.09 µg/dL

+0.03 µg/dL

+0.03 µg/dL

+BLL


Water supply with no corrosion control (pH=7.5)

Older homes

(Pb)

[1875 – 1955]

Post-war

(Cu)

[1955 – 1980]

15%

30%

55%

New home

(Cu)

[1980 – 2015]

50%

50%

Full LSL

(Pb/Pb)

Partial LSL

(Pb/Cu)

Full LSL

“BAD”

Full LSL

normal

10%

90%

27.7 ppb

0.4 ppb

0.4 ppb

10.9 ppb

19.8 ppb

(52,000)

# of children

[Pb]tap

(28,300)

(710)

(6,380)

(7,090)

+4.0 µg/dL

+3.0 µg/dL

+1.7 µg/dL

+0.06 µg/dL

+0.06 µg/dL

+BLL

Environmental sources of lead


0

50

100

150

200

250

300

350

1940 1960 1980 2000 2020

Le

ad

in S

oil

co

nc.

(µ

g/

g)

Lead concentration in soil (1946 - 2010) Health Canada State of Science report, 2013

Blood lead levels (BLL) observed in recent epidemiological studies or health surveys

BLL level (µg/dL)

Location Year Age No. in study Study

1.50 (GM) USA 2007-2008 1-5 years n=817 NHANES, 2007-2008

2.22 (GM) Hamilton 2008 - 2009 1-7 years n=643 Hamilton Public Health, 2011

1.12 (GM) St.John’s, NFLD 2010 1-6 years n=~300 St.John’s Public Health

1.35 (GM) Montreal 2010 1-5 years n=306 Levallois et al., 2014

0.77 (GM) Canada 2012-2013 3-5 years n/a Statistics Canada, 2013

85%

7% 7%

1%

<1%

+1.3 BLL

+0.6 BLL +0.3 BLL

+0.07 BLL

+0.07 BLL

Estimated BLL contribution

from tap water & %homes

in Ottawa

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

Flowing Litre-1 Litre-2 Litre-3 Litre-4

Lead conc. ppb

Importance of flushing tap for homes with “bad” LSL’s ?

11.7 – 12.9 ppb

3.6 ppb

Use of in-home filters to reduce lead

(4) store-bought carafe-style filters being tested (1 certified for lead removal)

cost approximately $15 - $35

harvested water from home with LSL = 4-7 µg/L

twice per week, pour 2 Litres through each filter (sample 2nd litre)

<0.2 ppb <1 ppb 1 - 2 ppb <1.5 ppb

“carafe” style pour-through filters reduce lead concentrations by 85 – 95% +3 months of testing and still performing well >80 Litres processed so far cost: $20-30

Zero water:

NSF certified

for Pb removal

Typical lead concentrations after filter

Questions, ideas, or

comments ?

[email protected]

Lead exposure in a municipal water system: City of Ottawa Case … Workshop/05 Ottawa_case... ·...

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