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Table 14: Partial List of Environmental Agents
That Interfere with Thyroid Function
Agent Example of Sources Mode of Action Human Studies
PCBs* Coolants and lubricants
Thyroid receptor
agonist/antago-
nist, can alter
levels of T4 and
TSH
Increase in TSH,
thyroid volume,
thyroid
antibodies
Organochlorine
pesticides
Pesticide on
crops
Accelerate
metabolism of T4
No human
studies
PBDEs* retardantsFlame^
Bind to thyroid
receptors,
displacing T4
from binding
proteins
Increase in
Hashimoto’s
BPA Plastic bottles
Antagonizes
thyroid
receptors
No human
studies
Perchlorate,
thiocyanate
Rocket fuel,
fertilizer, smoking
Inhibits iodine
uptake
No human
studies
Triclosan Antibacterial soaps Reduces serum T4 No human studies^
Isoflavones* Soy products Inhibits TPO activity
Potential
increase in
Hashimoto’s
Adapted from Eschler DC, Hasham A, Tomer Y. Cutting edge: the etiology of autoimmune thy-
roid diseases. Clin Rev Allergy Immunol. Oct 2011:41(2):190–197.
*Human studies associated this as a trigger or accelerator in the development of Hashimoto’s.