EPA’s 10-year review finds stronger evidence of harmful effects of lead

What Happened?

EPA finalized its Integrated Science Assessment (ISA) for Lead last week, updating its 2013 version with evidence published in the past decade about the potential effects associated with exposure to lead. Based on the new evidence, the agency revised its 2013 findings of the connection between lead and specific harms. 

Focusing on harmful human health effects from lead exposure that EPA found to be causal—the highest level—or likely to be causal, EPA made the following changes:

• Total nonaccidental mortality is causal: New finding, includes cardiovascular mortality.
• Cognitive effects in adults are causal: Upgraded from likely to be causal in 2013. 
• Renal effects are causal: Upgraded from suggestive of a causal relationship in 2013.
• Pregnancy and birth outcomes effects are likely to be causal: Upgraded from suggestive of a causal relationship in 2013.
• Female reproductive function effects are likely to be causal: Upgraded from suggestive of a causal relationship in 2013.

Why it Matters

ISAs are important because they are comprehensive analyses that EPA conducts in a rigorous manner with multiple levels of internal and external scientific review. They are a critical step in the multi-year process of determining whether the National Ambient Air Quality Standard (NAAQS) for Lead should be revised. Next up is a risk/exposure assessment. 

The ISA also impacts policy decisions made by other EPA programs and by other agencies. 

Our Take

EPA’s conclusions reinforce its overall efforts to reduce people’s exposure to lead. Last year, EPA found that lead in aviation gas for small engine airplanes contribute to harmful air pollution. Also, it quantified for the first time the socioeconomic benefits of reducing lead in drinking water that are associated with fewer premature adult cardiovascular disease deaths, ADHD cases, and low birth weight in babies in addition to improved IQ. 

However, the finding is no guarantee that EPA will tighten the NAAQS. In 2008, EPA dramatically tightened the 1978 NAAQS for lead after declining to make changes in 1991. In its 2016 review, EPA declined to tighten the standards despite the 2013 ISA finding stronger evidence about the harm associated with lead exposure.¹ 

Summary of Harmful Health Effects of Lead Found to be Causal

• Cognitive effects in children: Recent epidemiologic studies add to the evidence of harm below 5 microgram per deciliter (µg/dL) blood lead levels (BLLs). Recent animal studies support the finding.
• Attention, impulsivity, and hyperactivity behaviors in children: Recent studies of children with mean BLLs at or below 5 µg/dL support and extend 2013 conclusions.
• Cognitive effects in adults: Recent epidemiologic studies provide additional evidence of association with cumulative and early childhood exposure. 
• Cardiovascular effects and cardiovascular-related mortality: Strongest new evidence comes from studies demonstrating that lead increases blood pressure. There is substantially more evidence of cardiovascular-related death and changes in physiology.
• Renal effects: Recent studies support and extend 2013 conclusions particularly for mean BLLs at or below 5 µg/dL.
• Development effects: Recent studies show delays in onset of puberty in both boys and girls, particularly at lower BLLs. 
• Male reproductive function effects: Recent epidemiologic studies show consistent association with decreased sperm/semen production and quality.
• Total nonaccidental mortality: Recent epidemiologic studies build on evidence including at mean BLLs less than 2.5 µg/dL.

Lead is Bad for Plants and Animals Too! 

While we often ignore the impacts of lead on the environment, EPA confirmed its 2013 findings that the harm can be significant. Lead is causally associated with harm to reproduction, development, and hematology for both invertebrates and vertebrates as well as survival of invertebrates in terrestrial and freshwater (but not saltwater) biotas. It also harms growth of invertebrates and survival of vertebrates for freshwater biota and adds to harmful physiological stress on terrestrial plants. 

Next Steps 

Unleaded Kids will continue to track the NAAQS revision process and strive to translate ISA’s findings into policy affecting other routes of exposure.

1. See 2015 letter from EPA’s Childrens Health Protection Advisory Committee (CHPAC). ↩︎