Beyond the Water: Lead Exposure in Michigan’s Children

In recent years, child exposure to lead has received a lot of attention in Michigan.  From the Flint Water Crisis that began in 2014 to the Detroit Public Schools turning off drinking water in 2018 due to high levels of lead and copper in water fountains, a series of high profile events have elevated the issue.  What’s more, it’s a challenge that strikes at the most vulnerable among us – the health impacts of lead exposure are particularly harmful for children.

Using child lead testing data that D3 has received, we’ve conducted an analysis into the scope and scale of child lead exposure in Michigan.  We’re hoping to accomplish a few things with this blog series:

  • To shed light on the scope and extent of child lead exposure in Detroit and Michigan.
  • To put the terrible events in Flint and Detroit in perspective – are these isolated crises, or does lead present a broader issue that impacts children across the state? If so, to what degree?
  • To understand how factors like demolition activity, proximity to schools, and the age of the housing stock seem to affect the number of children with elevated blood lead levels.

In this post, we’ll introduce the data we’re using, and take a look at the current reported levels of lead exposure for children in Michigan.

Measuring and Reporting Lead Levels

Before we dive in to what the numbers are showing, let’s take a moment to walk through some basic definitions, background, and disclaimers.

How can someone be exposed to lead?  As the events in Detroit and Flint show, aging infrastructure (often built around lead pipes or lead pipe connections) can cause lead to leach into the water supply.  But water isn’t the only source.  Lead paint in older homes, emissions from industrial facilities like incinerators and power plants, and demolitions (particularly of older homes with lead paint and/or pipes) can all cause exposure.  And regardless of how it gets there, once it’s in the body, lead builds up, and doesn’t go anywhere.

For this analysis, we’ll be looking specifically at children under 18 years of age.  Even with this focus, this is a very complicated subject, and there are a lot of different ways to define what constitutes an “elevated” blood lead level (or EBLL).  As mentioned above, there’s a huge body of research on the harmful effects of lead on children, and different agencies and researchers use different definitions (medical professionals now argue that there is no known safe amount of lead for children).  After the Flint Water Crisis, Michigan lowered the threshold for an EBLL from 10 ug/dl (micrograms per deciliter) to 5. Furthermore, they round up when reporting results – so any child with a blood test of 4.45 ug/dl or higher is considered to have an EBLL.  Throughout this series, that’s the level we’ll use.

We’ve also made a few other assumptions.  Two types of blood tests are used to assess lead levels.  Capillary tests (based on a finger prick) are less reliable, but are usually used as the first screening test.  If a capillary test returns a high value, that test would ideally be followed by a venous test (from a vein) to confirm or disconfirm the capillary result.  However, venous tests sometimes also report falsely low levels, and not everybody follows up a capillary test with a venous one.  For this analysis, therefore, we decided to use the highest level of lead reported for a child in 2017, regardless of the test method.

In addition, we’re using a slightly different dataset than what the State of Michigan uses to officially report on EBLLs.  We received deidentified, address-level data from the Michigan Department of Health and Human Services, to which we then assigned latitude and longitude so that we could map the information.  However, the address level data was imperfect – about 5% of records either had no address, or had errors that prevented us from matching them to a location.  Given that, this analysis has been produced using 95% of the available data.  The coverage is higher in some areas than in others; for example, only 2% of addresses in Detroit were unable to be matched.

Finally, an important note:  not all children in Michigan are tested for lead.  Children who are enrolled in Medicaid are required to be tested at 12 and 24 months, or between 36 and 72 months if they have not been tested before then.  Anyone else can be tested voluntarily, regardless of age.  Testing tends to be concentrated in areas with a higher likelihood of exposure to lead poisoning.  That said, even though this isn’t a perfect sample, there are still some useful inferences that we can make from the data.

What’s the Scale of Child Lead Exposure in Michigan?

When examining the current level of child lead exposure in Michigan, it’s critical to mention that as a state we’ve already made significant progress in lowering children’s blood lead levels – in 1998, 42.7% of children age 6 and younger who were tested had blood lead levels above 5 ug/dl, while in 2015, that number was 3.4%.  However, as our analysis shows, we still have a long way to go – not only as a city, but as a state – to fully address this challenge.

Statewide, using the approach of selecting the highest test for each child out of our geocoded dataset, 8,882 out of 158,607 children tested in 2017 had an EBLL (roughly 5.6%).  However, when we drill in to look at the data city-by-city, disparities in EBLLs start to become apparent.  Children with EBLLs are concentrated heavily in larger central cities, but are also found throughout Michigan’s small towns, and even in some suburban areas.

The graph below shows the cities in Michigan that had the 10 highest rates of children with EBLLs, out of cities where 1,001 or more children were tested for lead.  Flint and Detroit both rank on this chart (Detroit with the 5th highest rate, and Flint with the 10th), but Grand Rapids, Battle Creek, Port Huron, and Kalamazoo all had EBLL rates that were at least 4 percentage points higher than Detroit.  Indeed, Grand Rapids has an EBLL rate more than three times higher than Flint’s 4.8%.  Eight of the ten cities on this list are central cities, representing the core of their metropolitan area.  Wyoming is the only suburban municipality.  Hamtramck, which is encircled by Detroit, has a similar EBLL rate.

Looking at the next chart, which shows cities with fewer children tested (between 101 and 1,000), we can see that central cities in some of the state’s smaller metropolitan and micropolitan areas (Muskegon, Jackson, Coldwater, Three Rivers, and Albion) continue to rise to the top.  Interestingly, the rates also start to climb, with several cities recording EBLL rates in excess of 20%.  Muskegon and Jackson have similar numbers of children with EBLLs as Flint, in spite of having less than half of Flint’s population.  Only one of the municipalities on this list (Highland Park) is located in Southeast Michigan or Metropolitan Flint.
For municipalities with fewer than 100 tests (most of which tend to be small cities and rural townships), the dispersed geographic pattern of high EBLL rates continues.  Negaunee (46.7%), Marquette Township (27.0%), Bessemer (20.8%), and Manistique (20.5%) all have high percentages of children with EBLLs, in spite of their comparatively small sample sizes and populations.  All four communities are smaller cities and townships located in the Upper Peninsula.

As the data shows, then, children with EBLLs are found statewide, in communities large and small.  In terms of magnitude, though, the data shows a very different trend.  In the chart below, we look at the ten cities in Michigan with the highest numbers of children who tested as having an EBLL.  These ten cities account for 53% of all children tested with EBLLs in the state.  However, they are home to only 15% of Michigan’s children (334,436 out of 2,227,763).  Detroit and Grand Rapids rank particularly highly, which would be to be expected as they are the two largest cities in the state, with the highest numbers of children tested.

However, even taking that into account, the difference is still stark, particularly when we use data from the State of the Detroit Child to contextualize these numbers.  Detroit is home to 28% of all children with EBLLs in Michigan, even though it contains roughly 10% of the state’s children.  Grand Rapids is home to roughly 2% of Michigan’s children, but over 8% of children with EBLLs.  While some of this could be due to higher concentrations of testing in Detroit and Grand Rapids than in other cities, other factors – including aging infrastructure, a housing stock built largely before lead paint was banned, and, in Detroit’s case, an intensive demolition program – are also likely to play a role.
So what can we actually learn from the data?

First, the issue of EBLLs in children extends across Michigan, and though it is concentrated in many of Michigan’s largest cities, small towns and mid-sized cities are also quite heavily affected.

Second, even in the context of the statewide issue that child lead exposure represents, the magnitude of the challenge facing Detroit and Grand Rapids is still notable.  These two cities account for 36.6% of all children tested with an EBLL, even though they are collectively home to only about 12% of Michigan’s young people.  In Detroit in particular, the sheer number of children experiencing this issue is concerning.

In the upcoming posts in this series, we’ll take a deeper dive into Detroit, seeking to answer more of the questions we posed at the start of this post.  In particular, we’ll look at where in Detroit these children are located.  We’ll also map these areas against the age of the housing stock, locations where demolitions are taking place and the locations of schools that reported particularly high levels of lead in their water to see if we can establish any inference between concentrations of children with EBLLs and environmental factors that may increase exposure to lead.

Stay tuned for more data about child lead testing in the near future on the State of the Detroit Child, both for Detroit and for other areas of Michigan.

If you’re worried about lead exposure, click here to see some helpful tips from the Environmental Protection Agency on how you can protect your family.

This blog series was created with the support of The Skillman Foundation.