ODWAC-MOECC Strategy Workshop on Lead (Pb)
ODWAC-MOECC Strategy Workshop on Pb (Lead): Agenda and Key Information
DATE: February 10th, 2017, 9:30 AM to 3:30 PM
LOCATION: 40 St Clair Ave W., 3rd Floor, Training Room “A”.
KEY CONTACTS: Scott Barrett, firstname.lastname@example.org, cell 416-994-7238
To develop advice on what additional scientific, technological and economic analysis MOECC needs to undertake, if any, to adopt and implement the more stringent drinking water standard for Pb as proposed by Health Canada.
To determine if consultation with stakeholders and / or further discussion with Health Canada is warranted.
All Members of ODWAC + MOECC/MOHLTC/PHO Staff
Invited MOECC Experts:
Jim Gilmore, SDB
Robert Dumancic, SDB
Aziz Ahmed, SDWB
Stephen Hetherington, SDWB
6 hour meeting, 30 minute lunch and two 15 minute breaks.
OVERALL APPROACH AND CONTEXT: Jim Smith and Satish Deshpande (15 minutes)
In considering both treatment and analytical achievability and the health risks associated with exposure to lead from drinking water, the Federal-Provincial-Territorial Committee on Drinking Water has proposed a MAC of 0.005 mg/L (5 µg/L) for total lead in drinking water, based on a sample of water taken at the consumer’s tap, using the appropriate protocol for the type of building being sampled. As this value exceeds the drinking water concentration associated with neurodevelopmental effects in children, every effort should be made to maintain lead levels in drinking water as low as reasonably achievable (or ALARA).
The Council will review the underlying science and policy for the recommended standard and identify any additional scientific, technological and economic analysis MOECC needs to undertake for Council to recommend that the guideline be adopted as an Ontario Drinking Water Standard and replace the existing ODWQS of 5 ug/L. (Note from the Chair: In framing our discussions think of the health based “bookend” as 0.08 to 0.008 ug/L and the ALARA “bookend” as 5 ug/L. We will need to explain to the Minister the basis for these two “bookends” and what the gap means in terms of protection (and risks) to sensitive populations.)
2. The discussion has been organized into 4 topic areas - each area with specific questions. Information copied directly for HC’s document is highlighted in italics. A summary of Council’s thinking to date is also summarized to aid discussion. Time limits have been prescribed for each area. Ministry staff will be participating as Subject Matter Experts and the information they provide and views they express will not be attributed to the MOECC unless they state that is the case. The four topic areas are:
i Health Assessment
ii Exposure Assessment and Risk Characterization
iii Risk Reduction Measures and Implementation
iv Stakeholder Consultation and Follow up with Health Canada
3. Jim Smith has agreed to facilitate the workshop. There will be a written summary of key discussion points however comments and opinions will not be attributed to any specific individual without their express consent. Scott Barrett will keep a running list of agreements, questions and issues on flipcharts as the workshop proceeds.
4. Key documents that have been referenced by the Council are listed and hyperlinked in Appendix 1 at the bottom of this webpage.
Confirm Science and Toxicology:
Health Canada’s bottom line
1. For neurodevelopmental effects: (60 minutes)
Although it is generally accepted that neurodevelopmental effects are the key endpoint associated with exposure to lead, there is still some debate as to whether a change in IQ of 1 point can be considered “adverse”. Although a threshold for lead cannot be identified, extending the concept of linear extrapolation typically limited to genotoxic carcinogens is the only approach that is currently appropriate for use in this assessment. The only universally adopted acceptable levels of risk of 10−5–10−6 are for genotoxic cancer endpoints. As these risk levels would be considered overly conservative for an endpoint such as a small loss in IQ, an acceptable level of risk ranging from 10−4 to 10−5 may be considered appropriate in the non-cancer risk assessment of lead. This would correspond to concentrations ranging from 0.008 to 0.08 µg/L for lead in drinking water, based on children aged 5–11 years, identified as the most sensitive population.
In developing the MAC:
The proposed MAC will have a significant impact on the BLLs of children, the most vulnerable population. It is estimated that reducing the MAC from 0.01 to 0.005 mg/L would lower the geometric mean percentage of children with BLLs exceeding 5 µg/dL by 7.2 percentage points (from 9.4% to 2.2%).
COUNCIL DISCUSSION TO DATE: Jim Gilmore and Jim Smith to lead discussion
Previous MOECC health assessment used a threshold approach and applied appropriate safety factors to develop a health based level that was considered protective. Current thinking is Pb is an “essentially” non-threshold neurodevelopmental toxin. Council did discuss key questions including:
Is there sufficient evidence that low BLL levels (1-2 µg/dL) are associated with adverse IQ/cognitive effects? Have studies been conducted in this low range?
Is there sufficient Evidence of ADHD and neuro-behavioural effects in the low BLL range (1-2 μg/dL)?
A key science policy question is what is an appropriate “de minimis” health based level below which there is negligible health concern. Options include:
· Health Canada’s approach considered a 1 IQ point deficit as “adverse”, then extrapolated using a standard non-threshold (i.e. cancer) approach to recommend that a 1/10,000 to 1/100,000 of an IQ point is de minimis.
· International and MOECC considered IQ point deficit as “adverse” then allocated a percentage of the 1 IQ deficit attributable to drinking water exposure using a standard cumulative/multimedia approach. Levels below this adjusted value are considered de minimus. Note: EFSA 2010 considered a decrease of 1 IQ point (i.e., 1% change in IQ) on full-scale IQ score as a benchmark response (BMR) because it was within range of observable values & would have impact on socioeconomic status of population & its productivity.
· Also, US EPA and CalEPA consider 1 IQ point to be significant from a public health perspective International agencies and MOECC considered 0.5 IQ point deficit as de minimus. Note: WHO/JEFCA 2011 at the population level, a decrease of 3 IQ points was deemed to be a concern, whereas a decrease of 0.5 IQ points was considered to be negligible.
· International and MOECC considerations that a delta (number to be determined) change to background blood lead levels in children is just discernable or de minimis. One approach could focus on determining a “threshold” level in drinking water that would result in a negligible increase in BLL (e.g. <0.1 µg/dL increase) given typical background exposures from dust, food, air.
Key Document(s): 1, 2, 3, 4, 5, 6, 7, 15
1. For other Non-neurotoxicity Health Effects: (30 minutes)
COUNCIL THINKING TO DATE: Jim Gilmore, Satish Deshpande to lead discussion
Other health effects arising from Pb exposures at very low levels and within the range of levels for neurodevelopmental toxicity have been demonstrated. These include carcinogenicity, blood pressure and other cardiovascular effects. Further analysis is needed to better understand how these health effects should be taken into account in establishing a health based standard for Pb or whether a neurodevelopmental basis to a Pb standard is sufficiently health protective.
Key Document(s): 7
TOPIC AREA 2: EXPOSURE ASSESSMENT AND RISK CHARACTERIZATON (60 minutes)
This is a complex area in terms of approach. Three ways of looking at the populations exposed to Pb in drinking water from municipal supplies are: 1. the general population; 2. the population having their water delivered through lead service lines; and 3. the sensitive population (children and expecting mothers) having their water delivered through lead service lines. The most insightful and robust model for analysis has been prepared by the City of Ottawa in estimating population exposures including the development of a Hi/Lo exposure scenario for sensitive populations (i.e. children).
· The proposed MAC will have a significant impact on the BLLs of children, the most vulnerable population. It is estimated that reducing the MAC from 0.01 to 0.005 mg/L would lower the geometric mean percentage of children with BLLs exceeding 5 µg/dL by 7.2 percentage points (from 9.4% to 2.2%).
COUNCIL DISCUSSION TO DATE: Ian Douglas, Jim Smith, Jim Gilmore to lead discussion
A province wide exposure and risk characterization assessment using a model similar to the “Ottawa Case Study” would provide more robust information on which to base a decision of the benefits of a more stringent standard. The analysis would provide estimates on the distribution of exposures for children in homes that have lead service lines. Such an analysis would provide information on the benefits of a more stringent standard and also provide information on the level of urgency for action and the need for interim advice to consumers on steps they can take to reduce their exposure until corrosion control practices or lead service line removal actions have been taken.
MOECC’s current policy for determining the need for Pb reduction for municipal residential drinking water systems continues to be supported by the Council. The current approach is based on specific requirements around sampling procedures (flushing, standing time, the volume and number of sequential samples collected etc.) and a prescribed statistical assessment of the analytical results.
Exposures from other media and sources (soil, air, food, and other incidental home exposures) also contribute to total exposure. Council believes drinking water nevertheless is an important contributor.
The characterization of risk is also dependent upon the science policy developed from the health effects assessment. Some approaches in the USA look at cumulative IQ point loss for the population of children exposed. The magnitude of the cumulative IQ point loss is highly dependent on what is considered de minimis and this measure of risk to a population is very new.
MOE’s exposure reduction strategy for Schools and Day Nurseries will provide an additional level of risk reduction for young children.
Key Document(s): 2, 5, 10, 11, 12, 18
TOPIC AREA 3: RISK REDUCTION MEASURES AND IMPLEMENTATION (90 minutes)
Health Canada bottom line (ALARA factors and use of filters):
COUNCIL DISCUSSION TO DATE: Aziz Ahmed, Robert Dumancic, Ian Douglas, Jim Smith to lead discussion
As a first step Council held a Meeting of Experts, October 16th to discuss corrosion control in terms of the current state of the technology and challenges in implementation province wide. MOECC invested considerable effort and time in 2007/8 in developing expertise on corrosion control and publish an extensive technical guidance manual for municipalities on the subject. There are three strategies for reducing lead exposure from drinking water for municipal residential systems:
1. Control Practices
2. Lead Service Line Replacement
3. Consumer actions to reduce exposure at the tap by flushing, the use of filters or using alternative drinking water sources
The first strategy require significant analysis in terms of the technologies available to reduce Pb and the costs associated with implementation for a range of source water types and current treatment approaches used in Ontario’s municipal residential drinking water systems. The second strategy requires significant policy discussion in terms of acceptable timelines, costs and the role of the province, municipality and homeowner in lead service line replacement. The third strategy requires policy direction from MOHLTC and PHO.
Council has discussed ALARA in the past. It does not have a specified protocol on how ALARA is evaluated or how costs and technology limitations are assessed. See Document 15.
Council does not support using a PQL of 5 ppm as limiting basis for establishing ALARA. Lower limits for Pb can be achieved. The PQL likely has not been reassessed and updated.
FOUR SHORT PRESENTATIONS TO PROMOTE DISCUSSION WILL BE DELIVERED AS FOLLOWS:
1. ALARA – what does it mean and how does Council want to apply (Jim Smith/Scott Barrett)
2. Ontario Experience with Corrosion Control Discussion (Aziz Ahmed, Ian Douglas)
A tale of Five Ontario Cities: Will look at how five Cities have implemented lead reduction strategies. Ottawa – Ian Douglas; City of Toronto, Hamilton and two smaller cities that have made reductions selected by Aziz Ahmed (Cities TBC)
3. Corrosion Control Broader Discussion (Robert Dumancic)
We will have a broad discussion on the limits of corrosion control, with consideration of the following:
· How far can corrosion control reduce Pb levels? How are the challenges/issues different in using corrosion control to lower Pb from 10 ug/L to 5 ug/L vs. from 5 ug/L to 1 ug/L, below 1 ug/L?
· What are the key challenges (technological, retrofit issues, operational, cost) in implementing corrosion control?
· What are the potential unintended consequences that can result from implementing corrosion control?
· Perspectives on optimized corrosion control for small, medium and larger drinking water systems?
4. Use of Filters and other risk reduction measures such as flushing (Jim Smith and Stephen Hetherington)
The City of Toronto has provided direction to its residents in steps they can take to reduce their exposure to Pb including the use of filters at the tap. Council will discuss the City’s policy decision and the role of filters in the content of ALARA for the province.
TOPIC AREA 4: STAKEHOLDER AND PUBLIC CONSULTATIO STRATEGY INCLUDING HEALTH CANADA FOLLOW-UP (60 minutes)
Appendix 1: KEY DOCUMENTS TO DATE:
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