Imani Reid, Xavier University of Louisiana
Erika Eitland, MPH, Harvard T.H. Chan School of Public Health
Lead is a naturally occurring heavy metal that can be found everywhere from our air, soil and water to our indoor environments including, homes, schools and work spaces. Lead is easy to extract, noncorrosive and easy to work. It is for these reasons that lead has historically been used in a variety of products such as paint, gasoline, pipes, batteries, cosmetics, and food containers (U. S. Environmental Protection Agency, 2017a). Although it has been regarded as a highly toxic substance since the early 1900s, lead was still widely used in consumer products and in gasoline and no regulations were set in place to control its use until the 1970s. The phase out of lead in gasoline in the 1980’s leading to dramatic declines in exposure. Today, our greatest exposures to lead come from lead in old buildings, either from paint, which can deteriorate or be disturbed by renovation and contaminate air, dust and soil (Brown, 2012), or from plumbing materials which can leach lead into water.
While lead is toxic to all people, regardless of length or type of exposure, fetuses and children are the most vulnerable to the toxic effects of lead due to increased gastrointestinal absorption and the undeveloped blood-brain barrier. Since lead is stored in bones and able to mobilize as calcium and iron stores are transferred from mother to baby, blood lead levels (BLLs) rise during pregnancy, creating a source of exposure to the developing fetus (World Health Organization, 2016). Lead exposure in utero and early childhood can significantly impact neurocognitive development and create neurological deficits that may persist through early adulthood (Brown, 2012). Herbert Needleman’s pioneering studies on childhood lead exposure, beginning in the late 1970s, have revealed that even low-level lead exposure could cause cognitive deficits, decreased IQ, impaired language skills, reduced attention span, and contribute to behavioral problems (Needleman, 1979). Subsequent studies have continued to find severe impacts on neurodevelopment of children at very low doses. These effects of childhood lead exposure can persist into later years. For example, another of Dr. Needleman’s studies found “a sevenfold increase in failure to graduate from high school, greater absenteeism, reading disability, and deficits in fine motor skills, reaction time” (Needleman, 1990).
Once lead enters the body it is distributed to the brain, liver, kidneys and bones (World Health Organization, 2016). Lead is stored in bones and teeth; BLLs may increase immediately following exposure, but decrease soon after; studies of teeth reveal a history of lead exposure over a longer period of time (Agency for Toxic Substances and Disease Registry, 2017). Due to the way it is stored and metabolized, lead absorption is enhanced by iron, calcium, and vitamin D deficiencies (Brown, 2012; Mason, 2014).
Until 2012, the Centers for Disease Control and Prevention (CDC) identified children with blood lead levels (BLLs) greater than ten micrograms per deciliter of blood as a concern. In response to emerging scientific evidence that suggested lead had significant effects on children at lower-levels, CDC lowered the reference value to five micrograms per deciliter (Centers for Disease Control and Prevention, 2012). This gradual decrease in reference value has been ongoing since the 1960s, when BLLs below sixty micrograms per deciliter were not considered dangerous. In 1975, the CDC lowered this level of concern to BLLs of thirty micrograms per decileter (Centers for Disease Control and Prevention, 1985), and in 1985, lowered this recommendation to twenty-five micrograms per deciliter. In 1991 the CDC introduced a new recommendation for intervention at ten micrograms per deciliter (Centers for Disease Control and Prevention, 1991), which remained the standard until 2012. It is important to note, however, that no true safe threshold has been determined for lead exposure (National Institutes of Health, 2017).
With acute exposure, symptoms of lead poisoning may include abdominal pain, nausea, constipation, headaches, and memory loss (Centers for Disease Control and Prevention, 2014). Greater health implications have been associated with chronic exposure. Lead has been shown to contribute to greater incidence of cold and flu among those with occupational exposure. Lead has also been shown to cause complications in the renal, cardiovascular, skeletal, endocrine, and reproductive systems including: hypertension, kidney failure, gout, peripheral neuropathy, increase risk of mortality from cardiovascular disease and cancer, osteoporosis, impaired thyroid function, infertility, preterm birth, and miscarriage (Brown, 2012; Mason, 2014; National Institutes of Health, 2017; Senut, 2012). Notably, adults with occupations in construction, plumbing, welding, and painting are at greater risk for lead toxicity (Occupational Safety and Health Administration, 2004). More recent research is also emerging to show that lead exposure in pregnant women can have epigenetic effects resulting in DNA changes in their grandchildren – meaning that lead exposure during pregnancy can potentially have multigenerational impacts (Sen, 2015; Senut, 2012).
An estimated 37 million homes across the U.S. contain lead-based paint; of these, 23 million homes are considered to have significant lead paint hazards (U.S. Department of Housing and Urban Development, 2011; National Center for Healthy Housing, 2017). Approximately one million of these homes house low-income families with small children, which equates to thiry-five percent of all low-income housing having lead-based hazards (U.S. Department of Housing and Urban Development, 2011; Jacobs, 2002).
…thiry-five percent of all low-income housing [has] lead-based hazards.
The prevalence of these hazards is greatest among homes in the Northeast and Midwest (U.S. Department of Housing and Urban Development, 2011; Jacobs, 2002). For instance, over the past two decades in Chicago, housing authorities have forced migration of low-income residents into subsidized housing on the city’s south and west sides. The incidence of lead poisoning in these primarily African-American communities is significantly higher than the city average.
The CDC recommends intervention when children present with five micrograms of lead per deciliter of blood. However until regulations were updated in January 2017, federal housing regulations allowed landlords to evade intervention unless children presented with twenty micrograms of lead per deciliter of blood. This placed numerous low-income children at risk of lead poisoning without the option of intervention (Hawthorne, 2015; U.S. Department of Housing and Urban Development, 2017). Similarly, in Massachusetts, it has been shown that race is a direct factor influencing lead exposure, even after factors such as poverty and age of homes are controlled for (Massachusetts Department of Public Health, 2016). “Massachusetts has the fourth oldest housing stock in the country, with approximately 71% of housing built before 1978,” only ten percent of these homes are reported as being lead abated, leaving ninety percent of these homes still contaminated and unsafe (Massachusetts Department of Public Health, 2016). One-third of children in Massachusetts live in high-risk communities where many older homes still stand, yet these children account for sixty percent of all cases of lead poisoning (Massachusetts Department of Public Health, 2016).
When children are not being exposed to lead in their homes, they are at risk in aging school infrastructure. The EPA estimates there are nearly 600,000 public schools and child care facilities not regulated under the Safe Drinking Water Act, which may or may not be conducting drinking water quality tests (U. S. Environmental Protection Agency, 2017b). Although drinking water is not the primary source of lead exposure, it is a significant concern given that most of our nation’s water infrastructure is nearly one hundred years old and significantly deteriorated in many cities and public schools (American Society of Civil Engineers, 2017). The primary issue is that within these communities where lead exposure is disproportionately impacting children’s health, multiple risk factors for lead poisoning exist, including: poor nutrition, poor air quality/ increased pollution, concentrated poverty, lack of green spaces, lack of resources, and older housing stock (Campbell, 2016). This should not only raise concern about community-level disparities in exposure, but should lead to further evaluation of environmental regulation and policy.
Beginning with the Clean Air Act and formation of the EPA in 1970, the U.S. has been undertaking initiatives to reduce lead exposure. Some significant initiatives include the following:
In addition to implementation of these laws and regulations, the EPA introduced the 3Ts for Reducing Lead in Drinking Water in Schools, which are “Training, Testing, and Telling” (U. S. Environmental Protection Agency, 2017b). Numerous health departments, nonprofits, community organizations, etc. have also taken initiatives to reduce lead hazards in their respective areas. However, work remains to be done; on a national level, it has been said that “the cost of detoxifying the entire nation hovers around $1 trillion […] Any federal effort to systematically identify and remove lead from infested households would be complex, decades-long, and require ongoing policy reform,” (Campbell, 2016). Systematic change would also require further investigation of the issues of environmental justice, thus, resources would need to be focused in areas with the most vulnerable populations.
Recommendations for individuals with small children or who may be living in older homes include repair chipping and peeling paint using lead safe work practices and certified workers (keeping occupants out of work area and clean up properly after work is done) (U. S. Environmental Protection Agency, 2012); work wet to control lead dust and paint chips during removal (wet-mop floors, wet wipe window ledges, spray warm water before vacuuming dust) (U. S. Environmental Protection Agency, 2012); eat a healthy diet that includes iron, calcium, and foods low in fat (National Center for Healthy Housing, 2008); and have children play in sand and grassy areas instead of dirt, and wash their hands after playing outside (National Center for Healthy Housing, 2008). Home testing kits are also available to test for lead in tap water (Columbia Center for Children’s Environmental Health, 2016).