Reformulating Lead-Based Paint as a Problem in Canada

Abstract

Leaded gasoline was officially removed from the Canadian market in December 1990. The removal of a major lead source and the subsequent decline in children's blood lead levels marked an important transition point and sparked the emergence of new discourse on lead in Canada. Today, childhood lead poisoning is viewed as a problem of the past or a problem of the United States. Sparse Canadian surveillance data supported this view. Moreover, tensions among federal agencies evolved into a power struggle, with Health Canada ultimately becoming the dominant authority, thereby relegating important research initiatives to obscurity and also shaping a vastly weaker regulatory response to lead than occurred in the United States.

The construct of childhood lead poisoning differs majorly between Canada and the United States. Canadian public health discourse portrays this issue as a problem of the past or as a US problem. US public health discourse portrays lead poisoning as a major and preventable disease, one requiring concerted and sustained effort to eradicate all sources of lead exposure for young children.

We offer what McHoul and Grace¹ termed a “counter-reading” of the history of childhood lead poisoning in Canada, with a specific focus on discourse related to lead-based paint in the post–leaded gasoline era. Our analysis identified dominant public health discourses on lead poisoning, highlighting the sociopolitical processes that shaped health care knowledge and influenced the way in which information on lead was produced and used by Canadian health care providers and policymakers. We also compared this analysis with US public health discourses on lead to identify the historical contingencies that permitted the dominant discourses in Canada to be created and maintained.

Differences between the 2 countries exist primarily because blood lead surveillance data for US children were readily available and easily accessible, whereas these data for Canadian children were relatively sparse and inaccessible. This contingency justified the use of Ontario's blood lead surveys as the surrogate indicator for Canada's children. As leaded gasoline was gradually phased out, and as children's average blood lead levels (BPbs) declined, the dominant Canadian view that childhood lead poisoning was a problem of the past, a US problem, or a problem mainly confined to children living in smelter communities was supported by limited survey data, selective references to US prevalence data, and a predominance of investigations found in Canadian literature describing lead poisoning cases as occurring in point-source communities. Conversely, this same contingency disadvantaged equally vocal discourse proposing that lead poisoning from exposure to residential sources did occur in Canadian children at a rate similar to that in which it occurred in US children.

Last, tensions arising between Health Canada and the Canada Mortgage and Housing Corporation (CMHC), Canada's 2 federal agencies assigned responsibility for health, housing, and lead, evolved into a power struggle in the mid-1990s, with Health Canada ultimately becoming the dominant voice, thereby diminishing CMHC's role and authority, but also relegating to obscurity important CMHC research projects, technical reports, and initiatives to remediate lead in housing.

These contingencies combined to produce a vastly weaker public health response to lead in Canada than in the United States, with the result that today no legislation exists at the federal level to protect Canadian children living in lead-contaminated older dwellings. Current discourse resulting from the Canadian Health Measures Survey, which emphasizes declining average BPbs, has further bred support for current policy despite important limitations.

FORMULATING THE PROBLEM OF LEAD-BASED PAINT IN CANADA, 1930–1990

Lead is important to study because of its population health effects. Evidence has suggested that BPbs lower than Canada's current level of concern (BPb < 10 μg/dL) harm children's renal and blood-forming systems, neuroendocrine systems, and reproductive systems.^2,3 Lead's properties as a developmental neurotoxin also deserve attention for their sociological implications. Lead-exposed children are more likely than less exposed peers to have lower IQ scores, manifested as poorer school performance, and behavioral effects diagnosed as attention-deficit/hyperactivity disorder.^2,4,5

Canadian discourse on lead-based paint first emerged in the 1930s in 2 of Canada's oldest health-related journals: the Canadian Medical Association Journal (CMAJ) and the Canadian Journal of Public Health (CJPH). In a 1932 issue of CMAJ, Mitchell⁶ described 2 cases of lead poisoning occurring in Montreal children: a 9-year-old girl who “stumbled when she walked, and could not use her hands properly to feed herself” and a 3-year-old girl hospitalized “in generalized convulsions of sudden onset.”^(p547) The ability to diagnose lead poisoning improved in the 1930s with the advent of new X-ray technology, which revealed lead lines in the growth plate of children's long bones.⁷ Using this method, Cushing⁸ identified 14 more lead-poisoned children admitted to Montreal's Memorial Hospital.^8,9 In a 1935 issue of CJPH, Ross and Brown¹⁰ described another 23 cases of lead poisoning in children from Toronto's Hospital for Sick Children. Collectively, Mitchell,⁶ Cushing,⁸ and Ross and Brown¹⁰ reported 39 cases of childhood lead poisoning within a 3-year span. Seven cases were fatal.^10,11 Cases were attributed to lead-based paint used on furniture, toys, and interior woodwork.^8,10 At least 2 US authors credited this early Canadian research with influencing the US public health response to lead.^12,13 Paradoxically, their influence in Canada appears to have been minimal. Apart from our writings, only one Canadian source cites Cushing and Mitchell's early work,¹⁴ and to date, only US sources cite Ross and Brown.

By 1926, 15 separate US publications described lead-based paint as a major source of poisoning, and by the late 1950s, US health authorities had identified more than 6000 lead poisoning cases.¹⁵ In sharp contrast, discourse on lead-based paint appeared only sporadically in CJPH and CMAJ over the next 60 years. Discussion of lead-based paint did not reappear in CJPH until a 1994 discussion weighing the pros and cons of universal screening.¹⁶ The topic resurfaced in CMAJ in 1947, but only peripherally. Penfield and Paine¹⁷ identified lead-based paint as the underlying cause of focal epilepsy in 2 children:

Ingestion of lead-containing paint was followed by coma of two days’ duration with generalized convulsions. Habitual seizures began a few months later.^(p523)

The same year Childe¹⁸ described lead poisoning as a possible cause of bone lesions in infancy and cautioned, “Plumbism is not so uncommon as is sometimes supposed and if kept in mind will be easily diagnosed.”^(p294)

A CMAJ editorial in 1952¹⁹ observed that 23 cases of pediatric lead poisoning were admitted to Toronto's Hospital for Sick Children (1951–1952) and offered that “repainted furniture causes much lead poisoning as young children nibble the wood through the layers of paint, which contains 7 to 27% of lead. A CMAJ editorial appearing just 3 years later, however, inferred that the problem was already resolved:

At the Hospital for Sick Children, Toronto, there has been a progressive decline in the number of lead poisoning admissions over the past 15 years. Before 1940 there was an average of 25 to 30 cases admitted each year; this has now decreased to two to four admissions per year. This decline is partly due to the education of parents by public health nurses and others as to the dangers of pica in small children, and partly to the decrease in the use of lead-containing house paints in the home. Legislation in Canada now prohibits the use of lead-containing paints on children's toys and children's furniture.^20(p611)

Paints manufactured in Canada could contain as much as 50% lead by dry weight.²¹ Perhaps Toronto children benefited from an education campaign, but lead poisoning cannot be eliminated simply through better hygiene practices, and, contrary to what the editorial expressed, Canada did not restrict the amount of lead added to interior paints until 1976.^22,23 Even then, the restriction permitted a lead concentration of 5000 parts per million, an amount 8 times as high as the US restriction of 600 parts per million established in 1978.²⁴ The box on the next page chronicles the appearance of Canadian and US regulations pertaining to residential lead sources.

THE CONSTRUCTION OF LEAD-BASED PAINT AS A US PROBLEM

Tenenbein's article²⁵ in a 1990 issue of CMAJ described 2 cases of lead poisoning occurring in Winnipeg children: a 32-month-old girl with a “17-month history of a voracious appetite for the paint peeling from the walls and window sills of her inner city home”^(p40) and a 26-month-old boy with persistent vomiting, who was eventually diagnosed with lead encephalopathy. Paint sampled from both homes revealed lead concentrations ranging from 25 000 to 122 000 parts per million.²⁵ Tenenbein's article established that lead-based paint continued to harm Canadian children well after the 1955 editorial²⁰ predicted the lead paint problem was close to being eradicated.

Timeline of Events in the History of Residential Lead Regulations in Canada and the United States: 1930–2010

Year	Event
1932–1935	Canada's first cases of childhood lead poisoning associated with exposure to lead-based paint are published in the Canadian Medical Association Journal and the Canadian Journal of Public Health.
1976	Canada restricts concentrations of lead in consumer paints to 0.5% (5000 ppm). Restrictions do not apply to exterior paints.
1978	The United States restricts lead concentrations in consumer paints to 0.06% (600 ppm). Health and Welfare Canada identifies 40 μg/dL as the blood lead level of concern (no age group specified).
1978–1979	Canada's first national blood lead monitoring survey, the Canada Health Survey, involved > 21 000 Canadians, aged 3 y to adult, and “covered the non-institutionalized Canadian population, excluding residents of the territories, Indian reserves and remote areas.”46(p16)
1985	The Centers for Disease Control and Prevention identifies an action threshold for blood lead levels of 25 μg/dL if accompanied by an erythrocyte protoporphyrin level of 35 μg/dL
1987	Canada reduces its blood lead level of concern from 40 to 30–35 μg/dL for male adults and 20–25 μg/dL for female adults and children
1988	Findings from the Ontario blood lead surveys (1984–1987) are published in the journal Science of the Total Environment.
1990	Leaded gasoline is banned in Canada for public consumption but is still available for commercial use (i.e., farm equipment, aviation fuel).
1991	The Centers for Disease Control and Prevention lowers the blood lead intervention level from 25 to 10 μg/dL. The Canadian Paint and Coatings Association voluntarily agrees to limit lead concentrations in interior paint to match the US standard of 600 ppm. The US magazine Newsweek features the stories of children poisoned from exposure to lead dust. The story triggers the discovery in Canada of 2 Medicine Hat, AB, children poisoned from home renovating activities. The Alberta cases are featured in a national television broadcast.
1992	Canada's Lead Swat Team is formed, consisting of representatives from 4 federal agencies: Health and Welfare Canada, Canada Mortgage and Housing Corporation, Consumer and Corporate Affairs Canada, and Environment Canada.
1994	Health Canada's interprovincial working group supports a lowering of Canada's blood lead intervention level from 25 to 10 μg/dL.
2002	Health Canada releases its national Lead Risk Reduction Strategy. The strategy addresses only lead in consumer products.
2004	The Canadian Medical Association Journal features the case of a Montreal boy poisoned from ingesting “lead-free” paint.
2005	Revisions to the Hazardous Products Act restrict lead concentrations in new interior paint to 600 ppm. Lead can still be added to certain classes of paint if the display panel carries the warning, “Danger. Contains lead. Do not apply to surfaces accessible to children or pregnant women.”
2008	Canada's 2nd national blood lead monitoring survey, the Canadian Health Measures Survey, takes place. Survey involves more than 5000 Canadians (aged 6–79 y).
2009	US regulations reduce the total concentration of lead in paint from 600 ppm to 90 ppm.
2010	Canada limits the total concentration of lead in paint from 600 ppm to 90 ppm. Lead can still be added to certain classes of paint if the display panel carries the 2005 warning. US regulations require contractors who renovate or repair housing, child care facilities, or schools built before 1978 to be certified in lead precautionary measures.

Tenenbein,²⁵ in describing his 2 cases, considered that other children in Canada might be similarly affected, although his struggle to locate supporting data was clearly evident:

The prevalence of neurotoxic lead levels in asymptomatic children is unknown in Canada. Sound epidemiologic studies of blood lead concentrations involving children living in Canadian inner city areas are needed to define the extent of lead poisoning from lead-based paint.^25(p41)

Research describing the extent of lead poisoning in Canada was lacking, although sporadic surveys from various Canadian cities during the 1970s pointed to a problem. A 1973 survey²⁶ of Montreal children (aged 0–6 y; n = 712), for example, identified 4.8% with a BPb of 40 micrograms per deciliter or more. A 1973 Halifax survey²⁶ identified 5.1% of children (aged 0–5 years; n = 184) with a BPb of 30 micrograms per deciliter or more. Missing, however, were Canadian studies investigating cases of lead poisoning occurring in children exposed to domestic lead sources (i.e., interior or exterior lead-based paint and dust).

By 1980, the first discourses characterizing lead poisoning as a US problem surfaced in Canada. A letter to CMAJ from C. J. Mackenzie,²⁷ head of the Department of Epidemiology, University of British Columbia, Vancouver, provides an example:

Lead poisoning due to ingestion of lead-based paint reached epidemic proportions in older housing areas in the United States… . There is no evidence of a serious health threat to Canadian children from environmental lead exposure. However, epidemiologic data confirming this assumption are scanty and largely limited to hospital records.^{(p1347–1348)}

Mackenzie's²⁷ discourse used a circular mode of reasoning: The abundance of US evidence pointed to a problem in the United States; a lack of similar evidence pointed to a nonproblem in Canada. This form of logic also appeared in a Royal Society of Canada report:

In striking contrast with U.S. experience, the Commission received no hard evidence that paint was a significant source of lead uptake. Indoor flaking paint has been seen as a main cause of high blood levels in U.S. inner cities (and some isolated rural cases). No evidence of such effects exists for Canada, though several briefs to the Commission have suggested that an impact must exist, especially in the older cities.^28(p265)

However weak these arguments may have appeared, at the same time they confirmed Tenenbein's²⁵ assertion that Canadian research into childhood lead poisoning was scarce. The following excerpt from Health Canada's Web site in January 2011, suggests that, decades later, rhetoric and not scientific inquiry continues to inform federal public health policy:

Very few cases of lead poisoning are documented in Canada each year. However, since low-level lead poisoning is often unrecognized, it is difficult to determine the number of Canadians affected by exposure to low levels of lead.²⁹

RECONSTRUCTING THE PROBLEM IN THE POST-LEADED GASOLINE ERA

Boothe and Harrison³⁰ suggested that the relative indifference paid to lead in Canada stems from a historic lack of national blood monitoring data. National surveillance data have been sparse, but the Ontario government has routinely monitored children's BPbs since the 1970s.³¹ The Ontario surveys (1984–1987) identified that 5.6% of urban Ontario children (aged 1–6 years, n = 1269) had BPbs of 20 micrograms per deciliter or more and 64% had BPbs of 10 micrograms per deciliter or more.³² These rates were comparable to US figures for the same period. In 1984, 5.2% of US children (aged 6 mos–5 years) had BPbs of 20 micrograms per deciliter or more; 17% had BPbs of 15 micrograms per deciliter or more.³³ The Ontario findings³² should have dispelled, once and for all, the notion that lead poisoning was only a US problem. Instead, the removal of a major lead source and the subsequent decline in children's BPbs seemed to strengthen the argument that lead poisoning was a problem of the past:

Since lead has been eliminated from gasoline and in the absence of clinical and laboratory evidence to the contrary, we believe that no serious threat of lead exposure to children exists in Canada.^{34(p518–519)}

Alternatively, lead poisoning was seen as a US problem:

In 1991, American public health authorities launched a population-wide prevention campaign aimed at eliminating pediatric lead poisoning by the year 2000. The extent of this program has elicited various reactions in Canada, where authorities have not considered that lead poisoning constitutes a public health priority for Canadian children.)^59(p.66)

At worst, lead poisoning was viewed as a potential problem requiring further study:

Old lead-based paint seems to be an important cause of the continuous prevalence of lead poisoning in the U.S.; however, since this situation has not been investigated carefully in Canada, it is possibly underestimated.^16(p168)

Leaded gasoline was officially banned in Canada in December 1990.⁶⁰ Average BPbs, at least in Ontario, did subside.^61,37 However, the residual 4% of urban Ontario children (1990–1992)⁶² identified with BPbs of 10 micrograms per deciliter or more in the post–leaded gasoline era was puzzling. Clearly, the problem had not been entirely eliminated. Smith,⁶³ a senior consultant with the Ontario Public Health Branch involved with the surveys, explained this anomaly by suggesting that exposure to “paint chips, paint dust during renovations, accumulated leaded dust in old houses” and other sources accounted for the remaining portion of affected children, and “parents should be warned.”^(p214) Two years later, however, Smith's cautionary message had changed:

The Centers for Disease Control and Prevention has described lead poisoning as one of the most common and preventable pediatric health problems in the United States. In Canada, however, blood lead levels have been consistently lower than in the United States: provincial and community surveys show blood lead levels in Canadian children have declined markedly over the past decade as lead has been phased out of gasoline.^{64,p.373(p373)}

Were Canadian blood levels consistently lower? The multiyear National Health and Nutrition Examination Surveys (NHANES) began monitoring US children's BPbs beginning in 1976 (1976–1980) and for the years 1988 to 1991, 1991 to 1994, and 1999 to 2004.^65–69 To date, Canada has conducted 2 national BPb surveys, the first of which occurred in 1978.⁷⁰ The 1978 to 1979 survey of Canadians aged 3 years to adult (n = 21 962) identified that 100% of boys and 96% of girls (aged 3–5 years) had BPbs sampling lower than 10 micrograms per deciliter⁷⁰—a peculiar finding given the era in which the survey took place. In Canada, the 1970s was a peak period for leaded gasoline consumption.⁷¹ Unleaded gasoline was introduced in 1975, but sales of leaded fuel did not diminish until the mid-1980s.⁶¹ Environment Canada²⁶ charged that the BPb results were not log normal, as one would expect, because 27% of the observed BPbs were 1 microgram per deciliter or less, “an unusual characteristic which cast doubt on the validity of the results.”^(p16) Health Canada's own Lead Working Group advised the use of caution when interpreting the results.^58(p22)

In 1994, the working group used a patchwork of community investigations to estimate a national rate for Canada: “In assessing the present status of blood lead levels in the Canadian population overall, it is necessary to rely on only a few substantial studies, mainly from Ontario, with some uncertainty existing as to just how representative these are of the situation across Canada.”^58,p.ii

The working group estimated that 5% to 10% of urban Canadian children had BPbs exceeding 10 micrograms per deciliter.⁵⁸ The absence of national surveillance permitted the use of Ontario's BPb surveys as a surrogate indicator for Canadian trends and left the door open for others to adopt a similar practice. Smith and Rea⁶⁴ used the prevalence rate for children aged 1–5 years (n = 395) living in an isolated area of northern Ontario for this same purpose: “Based on this survey, blood lead levels in Canadian children can be as low as about 3 μg/dL (geometric mean), with a 4% prevalence of levels over 10 μg/dL and no levels greater than 20μg/dL.”^(p375)

Smith and Rea⁶⁴ further compared findings from their 1995 survey with US survey data from 1984: “The relatively low lead levels seen in this survey and others in Canada contrast with the situation reported from the United States where an estimated 17% of preschool children had blood lead levels over 15 μg/dL in 1984.”^(p375)

Jin et al.⁷² used the same comparison to downplay findings from their 1995 Vancouver investigation, which identified 8.1% of children (aged 2–3 years; n = 172) with a BPb of 10 micrograms per deciliter or more:

The blood lead levels we found were much lower than those found in the Canada Health Survey, in the Ontario survey and in the United States National Health and Nutrition Examination Survey (1976-80).^(p1084)

The assessment by Jin et al.⁷² ignored more recent prevalence data from NHANES (1988–1991) that identified 8.6% of US children (aged 1–5 years) with a BPb of 10 micrograms per deciliter or more,⁷³ a rate much closer to that found in the Vancouver study.

Average BPbs in the US population began declining in 1977.⁷⁴ Average BPbs of Ontario children did not start to fall until 1984.⁶¹ Even after leaded gasoline was abolished, evidence pointed to a problem (Table 1). A Québec City investigation, for example, identified 10.8% of inner-city children (aged 1–6 years; n = 93) with a BPb of 10 micrograms per deciliter or more. In 6 of 10 cases, exposure was traced to residential sources such as paint and dust.⁷⁵ A 1995 investigation of London, Ontario, children (aged 0–17 years; n = 164) identified a 7.3% prevalence rate (BPb ≥ 10 μg/dL).⁷⁶ Again, lead-based paint was implicated as the primary source. Children living in homes built in or before 1945 had average BPbs that were 62.3% higher (P = .01) than those of children living in later built homes.⁷⁶ Although sparse, evidence from these and other community investigations (C. Balram and S. C. Giffin, unpublished data, 1993)^59,77,78 supported the view that children in Canada were being harmed by exposure to historic sources of lead-based paint, even as average BPbs declined.

TABLE 1.

Elevated Blood Lead Levels Among Children During and After the Leaded Gasoline Era: US and Canadian Surveillance Data, 1973–2010

		Elevated Blood Lead Levels
	No.	Mean ±SD (Median or 95% CI)	Level I, Range or %	Level II, Range or %	Level III, Range or %	Level IV, Range or %
NHANES II 1976–198065
Range, μg/dL			10–19	20–29	30–39	≥ 40
White, aged 6 mo–2 y, %	6186	15.0 ±0.56 (14)	64.1	17.3	2.2	0.2
White, aged 3–5 y, %	7455	14.9 ±0.41 (14)	13.6	15.4	1.6	0.1
Black, aged 6 mo–2 y, %	1164	20.9 ±0.96 (19)	50.2	34.2	13	2.3
Black, aged 3–5 y, %	1421	20.8 ±0.55 (20)	42.5	43.3	8.3	1.9
Canada Health Survey (1978–1979)a70
Range, μg/dL			<10	10–19	≥ 20	Unknownb
Aged 3 y–adult, %	21 962	-	65.6	12.1	-	32.5
Boys, aged 3–5 y, %	521	-	40.8	-	-	38.4
Girls, aged 3–5 y, %	474	-	70	4	-	26
Ontario (1984) a32
Range, μg/dL			10–19	20–25	> 25
Aged 1–6 y, %	1269
Urban, %		12.0 ±4.4	64	3.8	1.8
Suburban, %		10.0 ±3.5	44.4	2.2	1.6
Rural, %		8.9 ±3.9	33.3	2.7	0.8
Southern and northern Ontario (1984-1987)a31
Range, μg/dL			10–19	20–25	> 25
Aged 3–6 y, %	2459
Southern Ontario, %		10.0 ±4.18	64	1.1	1.8
Northern Ontario, %		7.7 ±2.92	44.4	2.2	1.6
NHANES III 1988-1991 Phase 1a73
Range, μg/dL			≥ 10	≥ 20	≥ 25
Aged 1–5 y, %	2234	3.5	8.6
Aged 1–2 y, %	1309	4.1 (3.7, 4.5)	11.5	3.5	1.8
Aged 3–5 y, %	925	3.4 (2.8, 3.5)	7.3	3.1	0.4
Aged 6–11 y, %	1587	2.5 (2.2, 2.7)	4	1.7	0.2
NHANES III 1991–1994 Phase 2a67
Range, μg/dL			10–19	20–25	> 25
Aged 6 mo–79 y, %	13642	2.3 (2.1, 2.4)
Aged 1–2 y, %	987	3.1 (2.8, 3.5)	5.9	-	-
Aged 3–5 y, %	1405	2.5 (2.3, 2.7)	3.5	-	-
Aged 6–11 y, %	1345	1.9 (1.8, 2.1)	2.0	-	-
Quebec City, QC (1991)a75
Range, μg/dL			≥ 10	≥ 20
Urban, aged 1–6 y, %	93	5.6 (5, 6)	10.8	1
Rural, aged 1–6 y, %	149	4 (4.1, 4.8)	1.3
London, ON (1993) a76			≥ 10
Range, μg/dL
Aged 0–17 y, %	164	4.7 ±2.00	7.3
London, ON (1993)77
Range, μg/dL			≥ 10
Aged 0–8 y, %	585	4 (–)	17.3
St. John, NB (C. Balram and S.C. Giffin, unpublished data, 1993)
Range, μg/dL			≥ 10
Aged 1–3 y, %	97	4.8 ±3.65	11.3
Vancouver, BC (1995)a72
Range, μg/dL			≥ 10	≥ 15
Aged 2–3 y, %	172	6.0 ±2.70	8.1	0.6
Moosonee and Moose Factory, ON (1995)64
Range, μg/dL			≥ 10
Aged 1–6 y, %	395	3.1 (2.97, 3.23)	4
NHANES 1999-200068
Range, μg/dL			≥ 10
Aged 1–5 y, %		(1.0, 4.3)	2.2
NHANES 1999-2004a69
Range, μg/dL			≥ 10
Aged 1–5 y, %	2532	1.9 (0.8, 2.0)	1.4
Aged 1–2 y, %	1231	2.1 (2.0, 2.2)	2.4
Aged 3–5 y, %	1301	1.7 (1.6, 1.9)	0.9
Quebec survey to establish reference level (2001)a100
Range, μg/dL			≥ 10
Aged 18-65 y, %	441		–
25th–97.5th percentile   (μg/dL)		2.0
Quebec survey to determine presence EBLLs in Quebec adults blood donors (2010)a101
Range, %			< 3	> 3	> 5	> 10
Aged 18–65 y, %	3490	1.9 (0.6, 5.6)	84	15.6	4.1	0.3
Canada Health Measures Survey (2010)a102
Range, μg/dL			≥ 10
Aged 6–79 y, %	5319	1.3 (1.24, 1.44)	< 1

Note. CI = confidence interval; EBLLs = elevated blood lead levels; NHANES = National Health and Nutrition Examination Survey. Leaded gasoline was banned in Canada and United States circa 1990.

^aGeometric means are reported.

^bThe term unknown indicates a laboratory result that was missing or improperly collected.

AN ISOLATED CONCERN

Sparse national survey data authorized the insertion of Ontario prevalence rates as the proxy indicator for Canadian trends, and selectively contrasting Canadian survey data with dated US surveys supported the view that the US lead problem was larger than Canada's. Lead's history in the CJPH archives has revealed a parallel but equally influential contingency, one that shaped the alternative view that Canada's lead problem, if it existed at all, was mainly confined to children living in smelter communities.

Between 1935 and 2008, CJPH published 16 separate articles on the topic of lead poisoning: a discussion of screening methods,⁷⁹ a case description of occupational exposure,⁸⁰ 4 commentaries,^16,81–83 2 product summaries,^14,84 6 field investigations of lead exposure pertaining to point-source communities.^85–90 Only 2 articles related to investigations of children living in nonindustrial settings: Ross and Brown's¹⁰ early commentary on lead-based paint and Smith and Rea's⁶⁴ 1995 survey, “Low Blood Lead Levels in Northern Ontario—What Now?”

The overrepresentation of smelter community investigations in 1 of Canada's high-profile public health journals supported the view, espoused by various authors,^{16,34,57,91–93} that childhood lead poisoning, if it existed at all, was primarily an isolated concern.

THE MEDICINE HAT CASES

By 1990, a growing body of international research, including Canadian research,⁹⁴ demonstrated that lead was harmful to children's developing brain and nervous system at BPbs of 10 micrograms per deciliter or less. In 1991, in response to this evidence, the Centers for Disease Control and Prevention (CDC) lowered its blood lead intervention level for children from 25 to 10 microgram per deciliter.⁹⁵ Canada followed suit in 1994 by adopting the same standard.⁵⁸

After the CDC revision,⁹⁵ US media reports began characterizing lead poisoning as an endemic problem rather than as an isolated concern.⁹⁶ A 1991 issue of Newsweek featured the stories of children who had been poisoned not from eating paint chips, but from ingesting fine particles of dust.⁹⁷ The burning, sanding, and scraping of lead paint produced fine lead particles that clung to surfaces, including children's fingers. Commonly described symptoms of lead poisoning included increased irritability and stomach complaints—symptoms resembling the flu, not those traditionally associated with poisoning.⁹⁷

The Newsweek story spilled into Canada and triggered the realization by a family from Medicine Hat, Alberta, that their children, too, might be lead poisoned. The family, given a copy of the article, recognized the same symptoms of irritability and stomachaches in their own 2 children.⁹⁸ The Alberta couple had also been renovating their century-old home, stripping paint off exterior walls and sanding storm windows. Their 1-year-old son's BPb was 30 micrograms per deciliter. Their 3-year-old daughter's BPb was 22.9 micrograms per deciliter.⁹⁸ Interior wall coatings contained lead concentrations as high as 140 000 parts per million. Exterior wall paint had lead concentrations as high as 120 000 parts per million. New exterior paint applied over old coatings contained 39 000 parts per million.⁴⁵

The Medicine Hat cases garnered national media attention in Canada. A 1991 broadcast of Marketplace⁹⁹ featured an interview with the family as well as experts from Canada, and the US. Host Bill Paul invited Roger Walker, senior project officer with Consumer and Corporate Affairs Canada, to explain Canada's laggard response to lead paint in contrast with vigorous American initiatives. Walker responded,

At this time we had no indication that the problems that the Americans were finding were indeed a problem in Canada. And the age of the housing stock in the United States is in many cities very much significantly older than Canada. There's a significantly higher percentage of Americans that are housed in what are referred to as lower income urban areas with often, in the United States, deteriorating conditions.⁹⁹

Thomas Spitler, senior researcher with the US Environmental Protection Agency, also a guest, was asked for his opinion. The United States had accumulated extensive research evidence that clearly associated lead paint and dust with children's elevated BPbs.³³ US laws to eradicate domestic sources of lead-based paint were first established in 1970,⁷⁵ although US advocates, too, had encountered their own set of obstacles delaying action.^103,104 Spitler responded:

I'm afraid that's about a 20 or 30 year old myth that lead paint is an inner city problem. Lead poisoning is a problem anywhere where you have a disturbance of high levels of lead paint and children exposed to the dust that results from that disturbance or renovation.⁹⁹

Marketplace⁹⁹ estimated that millions of homes in Canada contained lead-based paint, but most Canadians were unaware. Some cities, however, were aware of the problem. A 1991 investigation in St. John, New Brunswick, Canada's oldest city, identified that 53% of the 91 adults and children involved in a preliminary screening had a BPb of 10 micrograms per deciliter or more.⁴⁷ A follow-up survey identified 11.3% of St. John children (aged 1–3 years, n = 97) with a BPb of 10 micrograms per deciliter or more. (C. Balram & S. C. Giffin, unpublished data, 1993). The highest blood lead concentrations were found in families living in the older housing districts.⁴⁷ Richard Scott, a toxicologist involved with the study, also a guest on Marketplace,⁹⁹ offered his explanation for Canada's lethargy:

The level of awareness in the Canadian population would probably be close to zero. The reason being we have a perception, a generally held perception that we have legislated lead out of gasoline, out of paints, out of solder, and so, because of that, people will imagine that lead is no longer a problem. What they forget, however, is that we're dealing with a legacy of the use in the past.⁹⁹

In the end, the Medicine Hat family, overwhelmed by the projected cost to make their home lead-safe, opted to abandon their property.⁹⁹ The home was signed over to the bank's mortgage insurer, CMHC.

CMHC has 2 basic functions, to administer the National Housing Act (1985)³⁷ and to provide discounting facilities for loan and mortgage companies. After the Marketplace story aired, the program received more than 5000 requests for its lead fact sheet. A repeat broadcast ran the following year. The igniting interest in lead must have worried Canadian authorities. The CMHC had a number of housing units funded through its agency. How many of these contained lead-based paint? What if another family were poisoned? What if more Canadians started abandoning their homes? A Lead Swat Team was formed in 1992, consisting of representatives from 4 federal agencies: Health and Welfare Canada (which later became Health Canada), CMHC, Consumer and Corporate Affairs Canada, and Environment Canada. Finally, the issue of lead-based paint in Canada was attracting the political attention it deserved.

CANADA'S UNFINISHED BUSINESS WITH LEAD-BASED PAINT

Harrison and Hoberg¹⁰⁵ identified 3 steps involved in regulating a health issue: information on the problem is collected; decisions about appropriate actions (including inaction) are made; and agency decisions are implemented. Tensions between federal agencies evolved into a power struggle, with Health Canada ultimately emerging as the dominant organization, thereby diminishing the CMHC's role and authority but also preventing important research initiatives from being implemented.

Lead poisoning is a multifaceted problem that crosses the boundaries of public health, housing, and environment. The Public Health Agency of Canada Act¹⁰⁶ authorizes Health Canada to safeguard the health of Canadians. The Department of Health Act⁸⁵ equally obliges Health Canada to protect and monitor the physical, mental, and social well-being of Canadians. Lead itself is recognized as a priority substance under Schedule 1, Toxic Substances, of the Canadian Environmental Protection Act,³⁸ which further requires Health Canada to manage health risks related to lead.¹⁰⁷ As mentioned, responsibility for the investigation of housing falls within CMHC's mandate.³⁷

In 1992, US Congress passed Title X, the Residential Lead Based Paint Hazard Reduction Act,¹⁰⁸ which authorized the development of a national strategy to eliminate lead-based paint in all residential housing. Responsibility for implementing the act was divided among 3 federal agencies: the US Environmental Protection Agency, the CDC, and the Department of Housing and Urban Development. The Department of Housing and Urban Development was designated as the lead agency.¹⁰⁴ By 1992, it had examined the various methods, costs, and dangers involved in lead-based paint abatement—the primary strategy for the elimination of lead poisoning among US children.³³ A Baltimore, Maryland, study estimated that measures ranging from repainting and cleaning to full abatement cost between $1650 and $6000.¹⁰⁹

At the time of the Medicine Hat case,⁹⁹ the only abatement study in Canada had taken place in a secondary smelter community.⁴⁵ From 1991 to 1995, CMHC undertook various research initiatives related to lead-based paint: an abatement study of the Medicine Hat dwelling⁴⁵ an investigation of best practices for clean up after renovation development of a national training program geared to professionals involved in abatement, renovation, and repair activities⁴⁹ publication of a series of technical reports related to lead-based paint^44,52,53 and compilation of a resource manual listing Canadian research initiatives and federal and provincial guidelines pertaining to lead.⁴³ CMHC also codirected a follow-up investigation of the St. John, New Brunswick, homes that were associated with elevated BPbs.⁴⁷

After the Medicine Hat case, lead-based paint was close to being regulated. Information on the problem was collected, and decisions for appropriate actions were made. But lead was a housing problem, a medical problem, and an environmental problem. Under whose jurisdiction did it fall? Canada did not have a similar law to the US Title X¹⁰⁸ mandating shared responsibility for lead among federal authorities. CMHC, on its own, lacked the necessary authority to move its action plan into the crucial and final phase, implementation. In 1994, a Lead Working Group was appointed by Health Canada to review evidence supporting a lowering of Canada's BPb standard from 25 to 10 micrograms per deciliter. As discussed, a general lack of surveillance data frustrated the group's ability to make an informed appraisal, for which they compensated by piecing together limited survey data to estimate a national prevalence rate.⁵⁸

US researchers have estimated that 38 million US dwellings have lead-based paint somewhere in the home. Of these, 24 million contain significant lead-based paint hazards, and 3% of those constructed between 1978 and 1998 also contain significant hazards.¹²⁸ The extent of lead-based paint use in Canadian dwellings is unknown.¹³⁰ In 1991, the Canadian Paint and Coatings Association agreed to a voluntary restriction of lead concentrations of 600 parts per million or less, although this limit did not apply to lead concentrations in exterior paint. Cutoff dates for a Canadian risk era range between 1940⁷⁵ and 1990.¹³¹ In 1994, the working group issued a series of recommendations, mostly to address Canada's serious monitoring deficiencies. The working group proposed a national investigation to determine the extent of lead-based paint in Canadian dwellings but also targeted BPb screening of high-risk populations, including children living in smelter communities and “children living in houses painted internally or externally with lead containing paint.”^58(p.20) Various Canadian authorities have made recommendations to address childhood lead poisoning, including the working group (Table 2).

TABLE 2.

Recommendations From Various Canadian Authorities for the Remediation of Childhood Lead Poisoning in Canada

Recommendation	Outcome and Whether Decision Was Implemented
National blood lead surveillance25,58,76,110–113	Canada's 2nd national blood lead survey, 2007-2010, for ages 6–79 y (excluded children < 6 y).
Targeted blood lead screening of high risk groups16,58,76,91,111,113–116	Targeted blood lead screening only available in 2 smelter communities in Canada: Trail, BC and Rouyn, QC.
Investigate the extent of lead poisoning associated with residential sources25,76,58	Canadian House Dust Survey initiated in 2007; preliminary results for 3 cities presented as conference proceedings.13
Case finding16,58,112,117	Recent case reports: 9 children from Quebec, exposure source khôl122; 1 child from Quebec, exposure source not identified123; 1 child from Montreal, exposure source “lead-free” paint.124
Further research into sources of lead58,112	Health Canada periodically conducts market surveys of lead in jewelry/consumer products and food.
Proficiency testing for laboratories analyzing blood lead115	Proficiency testing is not mandatory in Canada although some laboratories subscribe voluntarily to quality assurance programs.
Awareness training for physicians and other health care providers58	None to date.
Public education34,112,114,118	Pamphlets54,125; booklets21; animated film126; Internet pages127,128
Training of contractors, tradespersons, home renovators49	None to date.
Mandatory reporting of blood lead levels16,58,119,120	Quebec only province in Canada with mandatory reporting of elevated blood lead levels; 42 cases ages 0-4 y reported between 2006 and 2009 (BPb ≥ 10 μg/dL).
Federal funding to assist/establish remediation programs (C. Balram and S. C. Giffin, unpublished data, 1993)	Canadian Mortgage and Housing Corp Homeowner Residential Rehabilitation Assistance Program — Homeowner.

The CDC's decision in 1991⁹⁵ to implement universal blood lead screening stimulated vigorous debate on both sides of the border.¹⁰³ Canadian discourse favored targeted screening of high-risk groups.^{16,58,110,132} Others proffered case finding as a solution,^{34,91–93,117} a strategy US health authorities had long ago rejected. Lead poisoning is a silent disease. No clinical symptoms were present to identify children at the new, lower BPb of concern.^95,133 Without relevant surveillance data to justify either approach, debate subsided, as did interest. In 2002, Sanborn et al.¹¹¹ observed that Canada had adopted neither targeted nor universal blood lead screening.

Between 1991 and 1995, the CMHC conducted sedulous investigations of lead-based paint, yet none of these research activities resulted in policy change. CMHC's national lead abatement training program never came to fruition, and it produced no further research reports on lead-based paint after 1995. CMHC's fading involvement and the formation, in 1994, of the Lead Working Group suggests that Health Canada assumed the lead role during this period. What was the outcome of this role change? CMHC's vigorous treatment of historic sources of lead-based paint contrasts sharply with Health Canada's follow-up plan, an approach that consisted primarily of issuing risk communiqués (Table 3).¹³⁴ Canada's National Lead Risk Reduction Strategy¹³⁵ addressed lead in consumer products only. Today, children living in smelter communities are the only population routinely monitored, and Québec is the only province requiring mandatory reporting of BPbs 10 micrograms per deciliter or more identified through case finding.¹²⁰ No regulations at the federal level protect Canadian children from exposure to historic sources of lead paint.¹⁰⁹

TABLE 3.

Federal Canadian Policy and Legislation Regarding Protection of Human Health From Lead

Organization	Legislation	Outcome
Health
Health Canada	Public Health Agency of Canada Act (2006)35; Department of Health Act (1996)36	National Lead Strategy addresses lead in consumer products only; risk communication materials include web pages, pamphlets, and booklets
Federal Provincial Committee on Occupational Health		Recommends national blood lead intervention level55-58
Housing
Canadian Mortgage and Housing Corp	National Housing Act (1938)37	Research reports related to lead-based paint remediation; development of worker training programs43-54
Federal-Provincial-Territorial Committee on Drinking Water		Recommends federal guidelines for lead in drinking water
Environment
Environment Canada, Health Canada	CEPA (1999)38	Lead identified as a toxic substance under CEPA; focus of act is on pollution prevention, secondary and primary smelter releases, and gasoline regulations
Canadian Council of Ministers of the Environment		Establishes national guidelines for lead in exterior soil (residential & industrial)
Toxic substances
Health Canada, Consumer Product Safety Commission	Hazardous Products Act and Regulations22,39-42	Limits lead content in new consumer paints, enamels, and other surface coating materials; children's products; interior and exterior surfaces of any building frequented by children; and jewelry intended for children (<15 y)

Note. CEPA = Canadian Environmental Protection Act.

Boothe and Harrison³⁰ suggested that US policy is further ahead than Canadian policy in all aspects pertaining to children's environmental health because of legislative differences that advantage US advocates:

[US] Congress tends to write detailed statutes in an attempt to ensure faithful execution of its will. In Canada, the fusion of executive and legislative functions in parliamentary government means that Cabinet both drafts laws and implements them. Not surprisingly, parliamentary governments typically produce laws that grant considerable discretion to the executive. This contrast shapes interest group strategies in two ways. With the advantage of environmental statutes that not only establish explicit mandates for the executive, but back them up with citizen suit provisions, U.S. interest groups contest virtually every major regulatory decision in court.^30(p293)

Certainly, Health Canada appears to have carefully chosen its response to lead. Recent Canadian federal regulations limiting lead content in consumer products were justified on the basis of 2 case reports occurring in 1998. Neither case was fatal.⁴² In 2004, Lavoie and Bailey¹¹¹ reported the case of a 4-year-old Montreal child who was “eating paint stripped from the walls of [his] new home.”^(p956) A BPb of 98 micrograms per deciliter confirmed acute lead poisoning. A visit to the boy's home by health authorities identified lead-free paint (< 0.5% dry weight or 5000 ppm) scraped from trim as the source of exposure.¹²⁴ Regulations limiting lead concentrations in new consumer paint to 600 parts per million came into effect in 2005,³⁹ 17 years after US regulations and, coincidentally, close on the heels of the Montreal case.

NEW FEDERAL INITIATIVES TO INVESTIGATE HUMAN LEAD EXPOSURE IN CANADA

Early discourse from the 1930s identified lead-based paint as a serious problem affecting Canadian children, mirroring similar concern in the United States. Yet, the public health response to lead in Canada followed a different trajectory, historically, than that of its neighbor. The topic of lead-based paint had barely taken root in Canada when, in 1950, lead poisoning was already being constructed as a declining concern. By 1980, the issue had been transformed into a US problem. The publication in 1988 of the Ontario blood lead survey data momentarily prevented lead from being cast as an exclusively US concern. Attention waned, however, as average BPbs of Ontario children further declined. National media coverage of the Medicine Hat cases in 1991 rekindled public interest by drawing attention to the lead-based paint problem potentially affecting a large proportion of Canada's housing stock. However, as average BPbs continued to fall, concern also shifted. After a brief surge of interest (1991–1995), tensions among federal agencies stalled all activity on lead-based paint. To date, no federal initiatives protect Canadian children living in lead-contaminated dwellings.

After a brief but inconsequential hiatus, the topic of lead poisoning appears to be the subject of renewed interest in Canada. Beginning in 2005, Health Canada produced a series of reports describing the health implications for children and adults of low-level lead exposure.^3,57,136 In a previous review,¹³⁷ we offered that these reports, although useful, add to the already large body of knowledge describing the physiological effects of lead. What is missing is context-specific information describing the extent of Canada's lead problem. How do people know, for example, whether childhood lead poisoning is even a problem in Canada? Although we originally intended our analysis to focus on discourse occurring between 1932 and 2008, we cannot ignore new discourse emerging from 3 recent federal initiatives, all of which appear poised to respond.

In August 2010, findings from the Canadian Health Measures Survey, Canada's second national investigation to measure concentrations of lead and other contaminants in the blood of more than 5000 Canadians, indicated that mean BPbs for populations aged 6 to 79 years have declined considerably in the 30-year span since the last nationwide blood lead survey in 1978.¹⁰² The decline is attributed to the phaseout of leaded gasoline, lead-containing paints, and lead solder in food cans since the 1970s. The Canadian Health Measures Survey¹⁰² reported that fewer than 1% of Canadians have blood lead concentrations higher than the Health Canada guidance value of 10 micrograms per deciliter. What should be pointed out is that this study excluded children aged younger than 6 years.

Children's BPbs peak between 18 and 36 months and decline thereafter; thus, a BPb of 10 is more readily found in children aged 1 to 5 years than in older children.^68,69,138 None of the supporting documents that accompanied the Canadian Health Measures Survey study explained this limitation.^139–141 The exclusion of a highly vulnerable population represents a serious flaw in this survey's design and challenges the legitimacy of using this study to describe a national prevalence rate for lead poisoning in Canada. Sadly, discourse emerging from Canada's latest national survey will likely further thwart public concern.

Complementing this survey is the Maternal Infant Research on Environmental Chemicals,¹⁴² which is tracking approximately 2000 women from the first trimester of pregnancy until the 8 weeks after birth. Lead is 1 of the 5 metals being monitored. Again, children aged 1–5 years are excluded from this investigation.

Of special interest will be findings from a 3rd national survey. The Canadian House Dust Study is Canada's first large-scale investigation of lead dust levels normally found on floors of residential dwellings. Preliminary findings have indicated that Canadian dwellings built before 1983 are more likely than later-built homes to contain lead dust on floors at levels associated with elevated BPbs in children (≥ 10 μg/dL).¹²¹

Because of space limitations, we have only briefly touched on these latter investigations. Detailed discussion of new public health knowledge produced from these surveys will be the subject of a future critical analysis.

CONCLUSIONS

First, sparse surveillance data enabled the construction of childhood lead poisoning as a US problem by permitting the insertion of Ontario survey data as a surrogate indicator for Canadian trends. Second, the abundance of public health literature describing investigations of lead poisoning in point-source communities privileged the view that lead poisoning was an isolated concern. Third, tensions among Canada's 2 federal agencies responsible for health, housing, and lead resulted in a substantially weaker legislative response to lead-based paint than occurred in the United States.

This thesis has unexplained holes. We cannot explain, for example, why some public health authorities in Canada chose to diffuse concern or why Québec public health discourse varies from discourse emerging from other provinces and consequently produced a distinctly different response. These matters are for future research. This much is known: lead-based interior and exterior paint was manufactured and sold in Canada until at least 1991, although legislation fully banning lead additives in paints did not come into effect in Canada until 2005.¹²² Weaker Canadian regulations, a general lack of public awareness, and a dampening of public concern by agencies perceived as having authority on this matter supported the contention that lead-based paint is potentially a larger problem in Canada than in the United States.

Various cost–benefit analyses have demonstrated that primary prevention (i.e., lead-based paint abatement) is cost effective.^143–145 A recent report by the World Health Organization¹⁴⁶ advised that lead-based paint remediation results in an even better return per dollar invested than do immunization programs. Many of the recommendations contained in the 1994 working group report⁴⁸ remain valid today. These recommendations should be revisited and set into motion through law. Learning from the US example, Canadian federal regulations should carry an enforceable deadline as well as citizen suit provisions to ensure regulations are implemented.

We have offered a counter-reading of the Canadian public health response to lead-based paint by examining the contingencies that shaped it. Through this analysis, we hope to bring Canada's attention back to this serious but preventable health concern.