How Environmental Toxins Can Affect the Thyroid

A 2007 study PMID: 17956155 noted that recent studies show that thyroid hormone receptors may be unintended targets of chemicals manufactured for industrial purposes. It also noted environmental toxins that can interfere with thyroid function and thyroid hormone signaling include: Phthalates, Bisphenol A (aka BPA), Polybrominated diphenyl ethers, Polychlorinated biphenyls

Polychlorinated biphenyls 

*the U.S banned production of these chemicals in 1977 when it became apparent their ability to accumulate in the environment and cause harmful effects.

Even though its been banned for decades, humans are still exposed to the toxic effects because of their resistance to decomposition and their capacity of bioaccumulation.

According to the CDC people are exposed to PCBs mainly from contaminated food and breathing contaminated air.

Widely used in the electrotechnical industry, used for insulating material and also found in: electrical equipment like voltage regulators, switches, and electromagnets, oil used in motors and hydraulic systems, cable insulation, fluorescent light ballasts.

PCBs accumulate in organisms through food as the main exposure source to humans with highest concentrations being found in fish (like salmon, shellfish), dairy products and animal fat. 

The environmental exposure comes from illegal disposal of oil waste and combustion of waste products in incineration plants. 

Polybrominated diphenyl ethers 

They are released into the environment at industrial manufacturing sites and leached from household products

Products that may contain PBDE:

-furniture foam
-wire insulation
-rugs
-upholstery
-computers
-small appliances

They are resistant to metabolism and can bioaccumulate in adipose tissue. PBDEs have been found in human blood, breast milk, placental tissue and in the brain. Breast milk levels on North American women indicate the highest body burden in the world.

Phthalates 

Essentially makes plastic more durable, soft and flexible.

According to the CDC women have higher levels of phthalate metabolites measured in urine than do men

Commonly found in:

-cosmetics: perfume, nail polish, hairspray, soap, shampoo 
-insecticide
-building materials
-detergents
-vinyl flooring
-shower curtains 

Exposure includes:

Eating or drinking things packages in plastic with phthalates
Dairy or meat from animals that have been exposed
Using cosmetic products that contain it

Breathing in phthalate particles in the air 

Bisphenol A (aka BPA)

-plastic food storage containers
-thermal paper receipts
-certain food packaging materials