Dr. Steve Krieger, Cowlitz County health officer, briefed the Board of Health on recent studies linking prenatal acetaminophen (Tylenol) use to autism spectrum disorder and attention-deficit/hyperactivity disorder, and on claims about vaccines and autism. "A causal relationship has not been established," he said, summarizing an FDA communication to clinicians and the broader literature.

Krieger explained epidemiologic concepts relevant to the debate, including confounding factors and sibling-comparison studies that attempt to control for family-level influences. He said larger studies that used sibling comparisons have seen previously reported associations weaken or disappear, suggesting shared family factors—genetics, maternal conditions or infections—may explain some earlier findings.

On clinical guidance, Krieger said acetaminophen remains the safest over-the-counter option for pregnant people compared with alternatives such as ibuprofen or naproxen, which have known fetal risks. "Use acetaminophen only when needed. It's the safest over the counter option," he said, and recommended using the lowest effective dose for the shortest period and consulting a healthcare provider.

Krieger also addressed vaccine safety and autism. He noted many studies claiming links are low quality or concentrated in a small set of flawed publications; high-quality, independent studies have not demonstrated a causal link between vaccination and autism. He described the scientific process and the importance of replication and controlling for confounders when interpreting conflicting research.

During Q&A, board members raised the possibility that underlying infection or fever—rather than acetaminophen itself—could be related to developmental risks, and expressed concern about study funding and potential bias. Krieger said those are reasonable concerns and reiterated that individual clinical decisions should be made with a healthcare provider.

The board did not adopt any new clinical directives or policies; the presentation was informational and intended to help members respond to constituent questions.