Jet Fuel-Induced Hypothyroidism Mechanisms and Clinical Implications

Proposed Pathophysiologic Mechanisms

Aromatic hydrocarbons in jet fuel may directly disrupt thyroid hormone synthesis by interfering with iodine uptake and utilization by the thyroid gland, analogous to how other environmental chemicals cause thyroid dysfunction, as reported by Clinical Nutrition 1
Disruption of thyroid peroxidase enzyme activity, which is essential for thyroid hormone production, and alteration of thyroid hormone receptor binding, affecting genomic and non-genomic thyroid hormone activity, have been documented, as reported by Environment International 2

Perturbation of lipid metabolism pathways, particularly unsaturated fatty acids and phospholipids, has been documented with hydrocarbon exposure, and amino acid metabolism disruption, which may affect thyroid hormone precursor availability, as reported by Environmental Health Perspectives 3

Phthalates and bisphenol A (BPA) cause hyperthyroid and subclinical hyperthyroid conditions by stimulating thyroid hormone production, and alter thyroid-stimulating hormone (TSH) regulation and modify concentrations of thyroid hormones including triiodothyronine and thyroxine, as reported by Environment International 2

The American Academy of Family Physicians recommends that while routine screening for asymptomatic thyroid disease is not recommended, targeted evaluation may be warranted for heavily exposed workers, as reported by American Family Physician 4
Annual TSH and free T4 measurement should be considered for personnel with chronic high-level jet fuel exposure, as reported by Genetics in Medicine 5
TSH >6.5 mU/L with normal T4/T3 indicates subclinical hypothyroidism requiring further evaluation, as reported by American Family Physician 4

Human epidemiology studies show weak and inconsistent thyroid effects without identification of specific causative chemicals, and confounding variables cannot be excluded as explanations for observed associations, according to the American Medical Association, as reported in JAMA 6
A systematic review of epidemiologic studies found slight evidence of associations between jet fuel exposure and various health outcomes, including neurologic, cognitive, behavioral, respiratory, and cancer outcomes, though thyroid-specific outcomes were not prominently featured, as published in Environmental Health Perspectives 7

Airport personnel in ground-support functions show biomarkers of exposure and effect, with proximity to running jet engines associated with increased disease risk and hospital admissions, as reported in Clinical Nutrition 8
The available epidemiologic data is sparse with low consistency in methods, limiting definitive conclusions about thyroid-specific effects, as noted in Chest 9