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Lead is a popular industrial metal but a potent neurotoxin. One of the marks of our industrial lifestyle is  how far we have spread lead – it’s in the air, soil, homes (e.g., dust, old paint, solder, toys and other consumer products), food and drinking water.[i], [ii] The good news is that most Canadians are much less exposed to lead now than we were before the 1970s, when leaded gasoline, lead-based paints and lead-soldered cans were phased out.[iii] Some research suggests that these reductions in lead exposure  have contributed to a large drop in violent crime; see https://www.siskinds.com/2007/11/12/lead-children-and-crime/.

But some Canadians,  especially children, are still exposed to too much lead  from several sources, including their drinking water.[iv]Municipally supplied drinking water contains very little lead. [v] However, lead can leach into drinking water in older homes from their own pipes and service connections (primarily in houses built before 1950) and plumbing solder (as recently as 1990).[vi],[vii] [viii]

People deficient in calcium, iron and zinc may absorb lead more readily.[ix] Chronic  exposure to even low lead concentrations can be harmful to infants, children and the unborn (lead crosses the placenta).[x] Even low-level exposure may cause intellectual and neurologic deficits.[xi] Lead accumulates in the bone,  and is released slowly  over many years.[xii] Extra lead may be released into the bloodstream during periods of stress (e.g., pregnancy, serious illness) or with loss of bone mass (e.g., in post-menopausal women). [xiii]

“Safe” levels of lead  keep dropping. Blood lead “levels of concern” in the US were 60 mcg/dL before 1970; this went to 40 mcg/dL in 1971, 30 mcg/dL in 1978, and 25 mcg/dL in 1985.[xiv] The current US and Canadian threshold for blood lead is10 mcg/dL,[xv],[xvi] ,[xvii] This may still be too high to prevent all adverse effects.[xviii],[xix]

Responsibility for drinking water quality rests on both the federal and provincial/territorial governments. Health Canada’s Guidelines for Canadian Drinking Water Quality, developed through the Federal-Provincial-Territorial Committee on Drinking Water, have been adopted by the provinces (e.g., Ontario’s Drinking Water Quality Standards Regulation)[xx] and specify a maximum lead concentration of 10 mcg/L (10 parts per billion) in drinking water. [xxi] These levels were last affirmed/approved in 1992.[xxii]

In April 2007, elevated lead was found in tap water in a number of London, Ontario homes. The  Chief Drinking Water Inspector ordered 36 municipalities to test for lead in older homes that were serviced by lead lines.[xxiii] This was followed by a provincial Lead Action Plan, which requires municipalities to test lead in their drinking water systems and take corrective action.[xxiv] A new regulation under Ontario’s Safe Drinking Water Act, 2002 requires annual testing and daily flushing of water systems in all schools, private schools, and most older day nurseries.[xxv]

Since then, drinking water in most of Ontario’s 10,000 schools and nurseries has shown acceptable test results for lead.  As of December 14, 2009, sampling frequency will now be relaxed for smaller systems with consistent good results.  At the same time, a new annual sampling requirement will be mandated for day nurseries with plumbing installed in 1990 or later, as evidence suggests that even these systems may have some risk of lead contamination.[xxvi],[xxvii]

People who live in older buildings, especially with small children, should consider taking some precautions at home:[xxviii] [xxix] [xxx] [xxxi]

·  Check with your municipality to determine whether the service connections (pipes from the home to the street) may contain lead; if so, test the home’s drinking water, and consider replacing the connection. While many municipalities have programs to replace municipally owned lead service lines, it is up to the homeowner to replace lead service lines from their property line to the house;

·  Lead levels are generally higher in taps that have been off for over 6 hours. If in doubt, run the cold water tap for 5 minutes each morning;

·  Use only cold tap water for drinking and preparing food (hot water likely contains more lead);

·  Minimize other sources of lead – replace pre-1950 windows, check toys for lead content, don’t put food or drink in leaded glass/crystal containers and encourage frequent hand-washing in children. And don’t let children put keys in their mouths.

Happy, healthy holidays to all.

December 13, 2009

Dianne Saxe, Jackie Campbell


[i] Payne M. Lead in drinking water. CMAJ 2008 July 29;179(3):253-254

[ii] Health Canada. Effects of lead on human health. 2008 November. http://www.hc-sc.gc.ca/hl-vs/alt_formats/pacrb-dgapcr/pdf/iyh-vsv/environ/lead-plomb-eng.pdf

[iii] Health Canada. Effects of lead on human health. 2008 November. http://www.hc-sc.gc.ca/hl-vs/alt_formats/pacrb-dgapcr/pdf/iyh-vsv/environ/lead-plomb-eng.pdf

[iv] Health Canada. Effects of lead on human health. 2008 November. http://www.hc-sc.gc.ca/hl-vs/alt_formats/pacrb-dgapcr/pdf/iyh-vsv/environ/lead-plomb-eng.pdf

[v] Health Canada. Effects of lead on human health. 2008 November. http://www.hc-sc.gc.ca/hl-vs/alt_formats/pacrb-dgapcr/pdf/iyh-vsv/environ/lead-plomb-eng.pdf

[vi] Health Canada. Effects of lead on human health. 2008 November. http://www.hc-sc.gc.ca/hl-vs/alt_formats/pacrb-dgapcr/pdf/iyh-vsv/environ/lead-plomb-eng.pdf

[vii] Payne M. Lead in drinking water. CMAJ 2008 July 29;179(3):253-254

[viii] Government of Ontario. What municipalities need to know about reducing lead in drinking water through corrosion control.  August 2008.     http://www.ontario.ca/drinkingwater/254372.pdf

[ix] Health Canada. Environmental & Workplace Health. Lead information package – some commonly asked questions about lead and human health.  Last modified April 23 2009   http://www.hc-sc.gc.ca/ewh-semt/contaminants/lead-plomb/exposure-exposition-eng.php#a43

[x] Health Canada. Effects of lead on human health. 2008 November. http://www.hc-sc.gc.ca/hl-vs/alt_formats/pacrb-dgapcr/pdf/iyh-vsv/environ/lead-plomb-eng.pdf

[xi] Payne M. Lead in drinking water. CMAJ 2008 July 29;179(3):253-254

[xii] Health Canada. Environmental & Workplace Health. Lead information package – some commonly asked questions about lead and human health.  Last modified April 23 2009   http://www.hc-sc.gc.ca/ewh-semt/contaminants/lead-plomb/exposure-exposition-eng.php#a43

[xiii] Health Canada. Environmental & Workplace Health. Lead information package – some commonly asked questions about lead and human health.  Last modified April 23 2009   http://www.hc-sc.gc.ca/ewh-semt/contaminants/lead-plomb/exposure-exposition-eng.php#a43

[xiv] Lanphear BP, Hornung R, Khoury J, Yolton K, Baghurst P, Bellinger DC et al. Low-Level Environmental Lead Exposure and Children’s Intellectual Function: An International Pooled Analysis. Environmental Health Perspectives 2005 July; 113 (7): 894-899

[xv] Payne M. Lead in drinking water. CMAJ 2008 July 29;179(3):253-254

[xvi] Health Canada. Environmental & Workplace Health. Lead information package – some commonly asked questions about lead and human health.  Last modified April 23 2009   http://www.hc-sc.gc.ca/ewh-semt/contaminants/lead-plomb/exposure-exposition-eng.php#a43

[xvii] International Programme on Chemical Safety. Inorganic lead. Environmental health

criteria 165. Geneva: World Health Organization, 1995. http://www.inchem.org/documents/ehc/ehc/ehc165.htm

[xviii] Canfield RL, Henderson Jr CR, Cory-Slechta DA, Cox C, Jusko TA, Lanphear BP. Intellectual impairment in children with blood lead concentrations below 10 mcg per deciliter. New Engl J Med 2003 Apr 17;348(16):1517-26

[xix] Health Canada. Environmental & Workplace Health. Lead information package – some commonly asked questions about lead and human health.  Last modified April 23 2009   http://www.hc-sc.gc.ca/ewh-semt/contaminants/lead-plomb/exposure-exposition-eng.php#a43

[xx] Ontario Regulation 169/03 under the Safe Drinking Water Act, 2002 at Schedule 2 (Chemical Standards) http://www.e-laws.gov.on.ca/html/regs/english/elaws_regs_030169_e.htm

[xxi] Health Canada.  Federal-Provincial-Territorial Committee on Drinking water of the Federal-Provincial-Territorical Committee on Health and the Environment. Guidelines for Canadian Drinking Water Quality Summary Table. 2008 May.  http://www.hc-sc.gc.ca/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/water-eau/sum_guide-res_recom/summary-sommaire-eng.pdf

[xxii] Health Canada –Environmental and Workplace Health.  Guidelines and Technical Documents: chemical/physical parameters: Lead. 1992 April (edited 1992 July). http://www.hc-sc.gc.ca/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/water-eau/lead/lead-plomb-eng.pdf

[xxiii] Ontario Environmental Registry – EBR Registry Number 010-0734.  Regulation exception notice: O. Reg 243/07 June 7, 2007. http://www.ebr.gov.on.ca/ERS-WEB-External/displaynoticecontent.do?noticeId=MTAwNzMz&statusId=MTUwNTEz&language=en

.  Additional information on legislative changes regarding lead and drinking water is at http://www.ontario.ca/ONT/portal61/drinkingwater/General?docId=133481&lang=en

[xxiv] Through amendments to O.Reg. 170/03 under the Safe Drinking Water Act, 2002 (Drinking Water Systems)

[xxv] Ontario Regulation 243/07 under the Safe Drinking Water Act, 2002 (Schools, Private Schools & Day Nurseries)

[xxvi] Letter from the MOE Chief Drinking Water Inspector to operators of schools, private schools and day nurseries. November 19 2009. http://www.ontario.ca/drinkingwater/278813.pdf

[xxvii] Ontario MOE. Summary of amendments to O.Reg. 243/07. http://www.ontario.ca/drinkingwater/278820.pdf

[xxviii] Government of Alberta. Lead in drinking water – questions and answers. Undated. http://www.environment.alberta.ca/documents/Lead_in_Drinking_Water_QandA.pdf

[xxix] Government of Ontario. What municipalities need to know about reducing lead in drinking water through corrosion control.  August 2008.     http://www.ontario.ca/drinkingwater/254372.pdf

[xxx] Health Canada. Effects of lead on human health. 2008 November. http://www.hc-sc.gc.ca/hl-vs/alt_formats/pacrb-dgapcr/pdf/iyh-vsv/environ/lead-plomb-eng.pdf

[xxxi] Health Canada. Minimizing Exposure to Lead from Drinking Water Distribution Systems. 2007 http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/lead-plomb-eng.php

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