Prenatal PFAS Exposure and Childhood Asthma Risk: Ronneby, Sweden Cohort Study

09 Apr 20265 min read0 viewsJournal Feed

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by Annelise J. Blomberg, Christel Nielsen, Beata Borgström Bolmsjö, Marie-Abèle Bind, Linda Hartman, Anna Saxne Jöud Background Early-life exposure to per- and polyfluoroalkyl substances (PFAS) may impact the developing lungs and immune system and increase the risk of childhood asthma, but no studies have been conducted in a high-exposed population.

The objective of this study was to estimate associations between prenatal PFAS exposure and childhood incidence of asthma and wheeze in Blekinge County, Sweden, where a subset of residents in the city of Ronneby was exposed to PFAS from drinking water contaminated by aqueous film-forming foam (AFFF). Methods and findings We constructed a register-based open cohort of 11,488 children born in Blekinge county between 2006 and 2013 and followed each individual from birth until age 12 or December 31, 2022.

Maternal address history was linked to water distribution records to create a categorical proxy variable for prenatal PFAS exposure from drinking water.

Clinical Editorial

Context and objective

This study investigates whether prenatal exposure to per- and polyfluoroalkyl substances (PFAS) from drinking water is linked to childhood asthma and wheeze in a high-exposure setting in Blekinge County, Sweden, where Ronneby residents experienced PFAS contamination from aqueous film-forming foam (AFFF).

Study design and population

A register-based open cohort design was used.
The cohort included 11,488 children born in Blekinge County between 2006 and 2013, followed from birth until age 12 or December 31, 2022.
Prenatal PFAS exposure was proxied categorically by maternal address history tied to drinking water distribution records, enabling classification into exposure levels (very high, high, intermediate, background).

Methods and analyses

Incident cases of wheeze and asthma were identified from administrative health records.
Primary analysis: Cox proportional hazards models estimating hazard ratios (HRs) for asthma and wheeze, adjusted for potential confounders including maternal smoking in early pregnancy, maternal age at delivery, parity, child sex, parental asthma, and socioeconomic factors.
Secondary analysis: Rubin Causal Model (RCM) approach to estimate average marginal effects in a very highly exposed subset, using a matched dataset balanced on measured confounders, to compare very-high exposure with background exposure.

Key findings

Overall, 18% of children were diagnosed with wheeze and 17% with asthma during follow-up.
Very high prenatal PFAS exposure was associated with incident asthma (HR 1.44; 95% CI 1.08–1.92).
No associations were observed for high or intermediate exposure levels or for wheeze in the primary analysis.
In the RCM analysis, the estimated cumulative incidence of asthma was 16.1% in the background-exposed group versus 26.7% in the very highly exposed group, indicating a potential effect under the causal-model framework.

Context and interpretation

The study provides evidence linking very high prenatal PFAS exposure from AFFF-contaminated drinking water to increased asthma incidence in childhood.
Associations were not observed for wheeze or for non-very-high exposure categories in the primary analysis; the causal-model analysis supports a potential elevated risk of asthma with very high exposure.
The authors emphasize replication in other populations and settings to confirm findings.

Limitations and reporting gaps

The exposure assessment used a categorical proxy based on residential water supply and did not measure individual PFAS levels, which may introduce exposure misclassification.
Hazard ratios and cumulative incidence estimates are provided; specificity about exact exposure durations beyond prenatal period or PFAS subtypes is not detailed in the content provided.