Lead service lines raise infant blood lead 1.6 times. Most infants are never tested in the window when this matters.

2025 JAMA Network Open study analyzed 1,210 Milwaukee infants 12 months or younger. Living in a residence with a lead service line raised the odds of an elevated blood lead level (3.5 µg/dL or higher) by 1.6 times after adjustment, and 2.26 times at the higher 5 µg/dL cutoff.

1.60x

adjusted odds of BLL above 3.5 µg/dL with LSL (95% CI 1.04-2.46)

2.26x

adjusted odds at higher BLL cutoff of 5 µg/dL (95% CI 1.23-4.16)

9.2M

estimated US homes with lead service lines (EPA 2023)

The dose-response is sharper at higher cutoffs.

Balza et al. 2025 ran logistic regressions at three different elevated-blood-lead cutoffs. The relative risk of LSL exposure increases as the cutoff increases, suggesting that LSL water is contributing meaningfully to the upper tail of childhood blood lead distribution, not just nudging a low-level baseline.

Adjusted odds of elevated infant BLL with LSL at primary residence

Balza et al. 2025, JAMA Network Open 8(12):e2550444. Adjusted for age, sex, race/ethnicity, Medicaid status, zip-code poverty, season of testing, age of residence.

Why infants are the worst case.

Infants 0-6 months reconstitute formula with tap water. They consume an average of 800 mL of formula per day, scaled to a 5-7 kg body weight. Per kilogram of body weight, that is roughly 6-8x the daily water consumption of an adult. If the source water has 5 ppb lead from corrosion of an LSL, the infant's effective dose is multiplied accordingly.

Lead absorption in young children is also higher than in adults: 40-50% of ingested lead is absorbed in children 0-6, vs 10-15% in adults. Put the higher per-kg intake together with the higher absorption rate and a still-developing brain, and infancy is the worst exposure window in a person's whole life. CDC's advice to start screening at age 1 misses that window.

What you can verify yourself in 10 minutes.

Find out if your home has an LSL: most US water utilities now publish an interactive map of service line materials by address. Search "[your city] lead service line lookup." If your municipality does not have one, your house was probably built before 1986 and your service connection should be assumed lead until verified.

Screening starts at age one, but the damage from reconstituted formula starts on day one. That year-long gap is the entire exposure window for the most vulnerable period in a child's neurological development.

If you have an LSL, the corrective interventions are concrete: run cold-water taps for 30-60 seconds before drawing water after any period of standing (overnight, after work). Use NSF/ANSI 53-certified filters for cooking and drinking. Never use hot tap water for formula or cooking, hot water dissolves more lead than cold. Replace the line on your side of the curb stop when financially feasible. Many municipalities now offer subsidized replacement programs.

If you have a formula-fed infant, the biggest thing you can do is easy. Never mix formula with hot tap water, run the cold tap first, and use bottled or filtered water for the first year. All of it is backed by evidence and it costs less than one can of formula.

Try it yourself.

Test the source closest to the formula bottle: your kitchen tap.

Fluoro-Spec is for painted dishware, the second-biggest direct exposure source after water. Use an NSF/ANSI 53 filter for the water and Fluoro-Spec for the dishware. You need both. A second kit drops to $30 automatically at checkout.

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The filter you bought may not cover lead.

NSF 42 filters skip lead, only NSF 53 catches it. And the pipe from the main to your meter may still be lead. This is happening now, not decades ago.

Support the mission to end lead poisoning. Get a FluoroSpec for someone you care about.

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Or keep reading. All of it is free.

Citations

Balza JS, Dawson AZ, Nelson D, Kaeppler C, Cusatis R, Flynn KE. Lead service lines and infant blood lead levels. JAMA Network Open. 2025;8(12):e2550444.
Hanna-Attisha M, LaChance J, Sadler RC, Champney Schnepp A. Elevated blood lead levels in children associated with the Flint drinking water crisis. Am J Public Health. 2016;106(2):283-290.
EPA Lead Service Line Inventory and Lead and Copper Rule Revisions. 2023.