In October of 2024, the Environmental Protection Agency (EPA) issued a final rule that requires drinking water systems throughout the country to identify and replace lead pipes in ten years.  What is the problem and how extensive is it?

Sources of Lead Exposure

Houses built before 1987 are a prominent source of lead exposure (chips of paint from old houses that small children eat and dust in old buildings painted with leaded paint).  Occupational exposure is also important–for instance, workers in industries that call for soldering are at risk.  Soil, especially near airports and heavy industry, have high lead content, and toys manufactured with lead machinery (especially from foreign countries) are a risk factor for lead poisoning in children.  And water from lead pipes is a significant source of lead.    

Does it Matter?

Lead is a potent neurotoxin, associated with an array of symptoms and diseases that constitute a virtual textbook of medicine.  To name a few in adults: high blood pressure, musculoskeletal pain, impaired memory, headache, abdominal pain, depression, miscarriage, premature birth, and kidney problems.

Effects on children are particularly concerning, as elevated lead levels can cause irreversible neurological symptoms, including development delay (both physical and cognitive), learning impairment, behavior disorders, deafness, and seizures.  

Research 

The National Library of Medicine recently published a review article that summarized the best research on the effects of lead exposure on the IQs of children.  Long story short:  there is no identifiable safe lead blood level (LBL).  IQ scores for children increase as lead blood levels decrease, even down to zero.  The higher the level, the greater the neurological impairment.  Similar studies have also documented the adverse effects of high lead blood levels on behavior.

Research on the effectiveness of lowering blood lead levels in adults is equally arresting.  A three percent increase in average adult IQ is correlated with a 20 percent decrease in male incarceration, poverty, high school dropout rates, and need for welfare.

Interventions

There are many ways to decrease LBLs.  For instance, soil contaminated by abandoned industry and defunct gas stations (where leaded gas can be in the soil) can be remediated.  The inhalation of dust with lead can be minimized by keeping children from playing on exposed soil.  There are effective water filters that can be fitted to faucets.  Extremely high levels of blood levels can be treated with intravenous agents that bind the lead, allowing for excretion in the urine

But Public Health interventions have been the most powerful ways to reduce the public’s exposure to lead, particularly those measures taken in the 1980s.  The last drop of leaded gasoline in the US was pumped in 1986, and leaded paint was proscribed in 1987.  The average childhood blood lead level in 1986 was 16 mcg/dL.  In 1994, it was 3.2.  The levels  have continued to fall, but, since there is no known safe level of lead in the blood, there is still work to be done.

Hence, the initiative to remove lead pipes.  Water tainted by lead is responsible for 20 percent of the lead that finds its way into the bloodstream of Americans, and even though mean blood levels in children have decreased by 95 percent since the 1980s, there is work to be done.  About 500,000 children in the US have blood lead levels greater than 3.5 mcg/d, which is the upper limit of “normal” according to the CDC. 

Cost

Of course the cost of replacing lead pipes is staggering.  Nine million homes in the US are served by lead pipes, and estimates for eliminating these pipes are about $4,700 per household.  Of But when you consider the above data about the benefits of lowering LBLs, it is clear that much of the cost, if not all of it, could be recouped with tangible societal benefit, both in terms of general health and economic impact. 

A Personal Note     

Like all primary care physicians, I have assessed many patients with complaints that defy assignment to conventional diagnostic categories.  They may complain of headaches, stomach pain, and/or diffuse muscle and joint pain.  These symptoms come and go, and these patients eventually undergo diagnostic tests (scans, endoscopies, blood tests, etc.) that do not reveal a specific cause of the complaints.  Such patients, dubbed with the title of having Somatic Symptom Disorder, often seek help from many different healthcare providers without resolution.  Anxiety and frustration are characteristic, and these patients often receive a psychiatric diagnosis. 

My research on lead poisoning has made me wonder whether I have routinely failed to identify a cause of these unfortunate  peoples’ distress that is modifiable.  Many researchers have asked the same question.  Investigations on the issue of blood levels and chronic disease are in the embryonic stage–so far nothing conclusive.