Lead in drinking water

Lead is a naturally occurring toxic metal that can be harmful to human health. Health effects of lead exposure can include neurological, cardiovascular, renal, immunological, reproductive and developmental effects, including developmental neurotoxicity in children that can have life-changing consequences. While the phasing out of lead in gasoline, paint, and other products has significantly reduced blood lead levels of Canadians since the 1970s, low-level exposure can still occur. One of the main routes of low-level lead exposure for the public today is via drinking water.  

Although source water from aquifers and reservoirs is generally low in lead, water can become contaminated in the distribution system due to leaching from lead service lines (LSL) and premise plumbing. Older buildings built before 1975 are more likely to be impacted by lead pipework, but exposure can also occur in newer buildings where low-level leaching from some brass fittings or soldered plumbing joints can occur. The problem can be exacerbated in areas with corrosive (low pH) water, and in buildings where water is left standing in pipes for long periods.

Health Canada reduced the Maximum Allowable Concentration (MAC) for lead in drinking water in 2019 from 10 µg/L to 5 µg/L. Many jurisdictions in Canada are now working to reassess levels in drinking water and to identify actions to reduce exposure, particularly for children and pregnant women. (See Mar. 24, 2022 recording of “Health Canada’s new lead guideline and results of an Indigenous Services Canada, FNIHB drinking water sampling survey in children's facilities”) The resources presented here are intended to assist public health practitioners to:

• Understand the key issues around lead in drinking water including exposure, health effects, and current guidelines
• Provide practical advice on sampling, testing, and mitigating lead exposure in schools and childcare settings
• Understand the issues associated with identification and replacement of lead service lines (LSL)

Exposure, health effects and guidelines

• Basic information about lead in drinking water (US EPA, 2022)
  This webpage provides general information about exposures to lead in drinking water, health effects, and steps that can be taken to reduce exposure.

• Guidelines for Canadian drinking water quality: guideline technical document – lead(Health Canada, 2019)
  This guideline technical document presents background, context, science and research as well as technical considerations that formed the basis for reducing the MAC for total lead in drinking water from 10 µg/L to 5 µg/L. For more information on lead exposure, see the Lead Information Package.

• Public health consequences of lead in drinking water (Levallois et al. 2018)
  This review article presents the evidence of lead exposure via drinking water, the possible health impacts, and mitigation strategies to reduce exposure.

• Preliminary study of lead-contaminated drinking water in public parks – an assessment of equity and exposure risks in two Texas communities (Fawkes and Sansom, 2021)
  This research article highlights the potential for exposure to lead in drinking water outside home or school environments, by reporting on lead levels detected in drinking water fountains in public parks.

• Metals in the drinking water of First Nations across Canada (Schwartz et al. 2021)
  This research article reports on results of lead in drinking water measured in the First Nations Food, Nutrition and Environment Study (FNFNES). See also: Lane et al. 2020 for additional reporting on lead in drinking water from FN communities in Atlantic Canada.

• Children drinking private well water have higher blood lead than those with city water (MacDonald Gibson et al., 2020)
  This research article reports on the increased odds of elevated blood lead levels in children in homes supplied by private wells rather than community water systems, highlighting the importance of well materials and plumbing fittings to lead exposure. See also Sweeney et al., 2017 for a comparison of lead levels in unregulated private wells in Nova Scotia.

• Public health and industry: partners in reducing lead exposure (Eykelbosh, 2017)
  This NCCEH presentation, delivered at the Canadian Water Quality Association (CWQA) meeting in May 2017, uses Flint, Michigan, as a case study to examine the factors leading up to a public health disaster, and discusses how the drinking water treatment industry and public health professionals can collaborate to reduce Canadians’ risk of lead exposure.

Understanding sampling protocols

• Variability and sampling of lead (Pb) in drinking water: assessing potential human exposure depends on the sampling protocol (Triantafyllidou et al., 2020)
  This review article describes the root causes of variability in lead in drinking water and sets out the limitations of various sampling protocols for providing accurate estimations of human exposure.

• Testing for lead in school drinking water: a summary of sampling protocols (Barn et al, 2019)
  This NCCEH review summarizes four Canadian protocols for sampling lead in school water, including those from Ontario and Québec, and two from Health Canada. See also O’Keeffe et al., 2019, which expands the review to include sampling protocols from US agencies.

• True exposure to lead at the tap: insights from proportional sampling, regulated sampling and water use monitoring (Riblet et al., 2019)
  This research article evaluates different water sampling protocols for lead to compare their accuracy in determining weekly water lead levels (WLL).

• Lead testing program interactive map (City of Winnipeg, 2022)
  This interactive map provides an example of how a municipal utility is providing public access to lead in water testing results.

• Flushing and sampling for lead (Government of Ontario, 2021)
  This guidance document provides information on the requirements for testing lead in water at schools and daycare centres in Ontario, and periodic, preventive flushing of facility plumbing. At-a-glance guides for sampling and flushing are also available.

Detecting and mitigating lead exposure in schools and child care facilities

• Health Canada’s new lead guideline and results of an Indigenous Services Canada, FNIHB drinking water sampling survey in children's facilities (NCCEH, 2022) 
  This webinar recording explores Indigenous Services Canada's sampling survey in Alberta Region to determine community lead levels in schools and daycares. 
   
• 3Ts for reducing lead in drinking water (US EPA, 2022)
  This website explains the 3Ts approach to reducing lead in drinking water, which consists of training, testing, and taking action. Detailed resources are provided including the 3T’s toolkit, and child care and school specific resources.

• A critical opportunity: detecting and reducing lead in drinking water at child care facilities (Stanbrough et al. 2022)
  This research article summarize results of a US pilot study on approaches to testing and reducing lead in drinking water at child care facilities. The effect of flushing, aerator cleaning, and fixture replacement were assessed, with flushing found to be the most effective method for reducing lead.

• Reducing lead exposure in school water: evidence from remediation efforts in New York City public schools (Latham and Jennings, 2022)
  This research article reports on the impact of targeted replacement of drinking water fixtures with elevated lead levels (> 15 ppb) in New York City schools. The study found that this measure reduced but did not eliminate lead in drinking water in the schools tested.

• Guidelines on evaluating and mitigating lead in drinking water supplies, schools, daycares, and other buildings (Government of British Columbia, 2019)
  This guidance document provides information on the roles and responsibilities of BC public health professionals and other stakeholders in reducing lead exposure in a variety of settings, including schools.

• Sampling in schools and large institutional buildings: implications for regulations, exposure and management of lead and copper (Dore et al., 2018)
  This research article reports on a drinking water sampling study at 8 schools and 3 institutional buildings in two Canadian provinces, where the effect of water corrosiveness, corrosion control, and flushing on lead concentration were assessed.

• A consumer tool for identifying point of use (POU) drinking water filters certified to reduce lead (US EPA, 2018)
  This fact sheet provides practical tips for identifying water filtration products certified to reduce lead in drinking water.

Identification and replacement of lead service lines (LSL)

Several Canadian cities have LSL replacement initiatives underway (e.g., See Calgary, Saskatoon, Toronto, Ottawa, Montreal, Halifax)

• Lead Service Line Replacement Collaborative (LSLR Collaborative, 2022)
  This website provides a range of resources on LSL replacement including a roadmap for communities to develop and implement LSL replacement programmes, cases examples, and other downloadable resources.

• Impact of service line replacement on lead, cadmium, and other drinking water quality parameters in Flint, Michigan (Rockey et al., 2021)
  This research article reports on the impact of LSL replacement on drinking water quality. In the short-term (weeks), elevated lead levels persisted (predominantly particulate lead) following LSL replacement. This may have been due to line disturbance, or lead in premise plumbing, including plumbing seeded with lead from LSL over many years.

• Lead levels at the tap and consumer exposure from legacy and recent lead service line replacements in six utilities (Deshomme et al., 2018)
  This research article reports study the impact of partial and full lead service line replacement on drinking water quality. The study found that partial LSL replacement resulted in greater short-term lead levels for up to 18 months, which reduced over time. In comparison, full LSL replacement decreased levels immediately.                       

• Evaluating the effects of full and partial lead service line replacement on lead levels in drinking water (Trueman et al., 2016)
  This research article reports on the effects of full and partial LSL replacement, finding that full replacement resulted in significantly lower lead levels within one month, but partial did not achieve  replacement were not as good, and could result in short-term increases in lead levels.

This list is not intended to be exhaustive. Omission of a resource does not preclude it from having value.