Vaping uses electronic cigarettes or vape devices to heat a liquid, producing an inhalable aerosol. The thyroid gland, located in the neck, produces hormones that regulate metabolism, growth, and development.
Vaping Product Ingredients and Potential Risks
E-liquids, heated in vape devices, typically contain propylene glycol (PG), vegetable glycerin (VG), nicotine, and flavorings. PG and VG form the e-liquid base and produce the aerosol. Nicotine, a highly addictive chemical, is present in most e-liquids, though nicotine-free options exist.
Vape aerosol can also contain other substances, some formed during heating. These include heavy metals like lead, cadmium, nickel, tin, arsenic, and chromium, which can leach from heating coils or be contaminants in the e-liquid. Formaldehyde and acrolein, known harmful chemicals, can also be generated during heating, particularly at higher temperatures.
Flavorings, including chemicals like cinnamaldehyde, vanillin, and benzaldehyde, are also a concern. While some are safe for food consumption, their safety when inhaled is not always established, as lungs process substances differently than the digestive system. Many of these chemicals, including heavy metals and volatile organic compounds (VOCs), are toxic or irritating to human tissues.
Mechanisms of Thyroid Disruption
Chemicals in vape aerosols may interfere with thyroid function. Heavy metals, such as lead, cadmium, mercury, and arsenic, are known endocrine disruptors. These metals can damage thyroid cells, impair hormone synthesis, or interfere with iodine uptake, a mineral essential for hormone production. Mercury, for instance, can bind to selenium, crucial for converting inactive thyroid hormone (T4) to its active form (T3).
Vaping can also induce oxidative stress and inflammation. Oxidative stress, an imbalance between free radicals and antioxidants, can lead to cellular damage affecting endocrine glands like the thyroid. Chronic inflammation can also disrupt hormone regulation.
Vape aerosol components can also modulate immune function. Some endocrine-disrupting chemicals, including certain heavy metals, may alter immune responses. This could trigger or worsen autoimmune thyroid conditions like Hashimoto’s thyroiditis or Graves’ disease in genetically predisposed individuals. Nicotine, a primary e-liquid component, can indirectly affect the endocrine system by influencing the hypothalamic-pituitary-thyroid axis, which regulates thyroid hormone production. This disruption could lead to thyroid hormone imbalances.
Emerging Research and Scientific Evidence
Research into the direct link between vaping and thyroid health is in its early stages. Studies are limited by the products’ newness, diverse e-liquid formulations, and the long-term nature of potential health effects. While theoretical mechanisms exist, definitive long-term human studies are needed.
Preliminary findings have begun to explore this connection. For example, a case-control study involving young men who used e-cigarettes found increased free triiodothyronine (FT3) and free thyroxine (FT4) levels and decreased thyroid-stimulating hormone (TSH) compared to a control group, indicating a possible effect on thyroid function. Another case report suggested a potential reversible association between vaping and subclinical hypothyroidism, with possible contributing factors including lithium exposure from vape device batteries.
While some vape aerosol components are known endocrine disruptors, their specific impact on the thyroid is an area of ongoing investigation. The scientific community continues to gather comprehensive data through long-term human studies.