M9.2 Six Chemical Classes

Chemical Summary

1. Highly Fluorinated Chemicals 

• man made chemical that has been in production since 1940
• two most well known chemicals in this class are PFOS and PFOA (C8)
• resistant to breakdown in the environment and in organisms 
• high levels found in the animals even in remote areas
• used on products such as carpeting, upholstery, apparel, food packaging, non-stick cookware, paint, and dental floss to provide oil and water repellency 
• particulate molecules are found in air, dust, and groundwater, which are the main sources of exposure for animals and humans 
• human health effects include cancer, thyroid disease, delayed puberty, early menopause, decreased testosterone, infertility, decreased immune response, and increased cholesterol 
• C4 and C6 may not be safer alternatives (more research is needed)
• it is most likely that highly fluorinated chemicals are not necessary in most applications 

2. Antimicrobials

• specifically looking at the widespread use of triclosan and triclocarban 
• increasing use in everyday products such as personal care products, soaps, deodorant, clothing, toothpaste, cosmetics, kitchen supplies, furniture, toys, sporting equipment, and school supplies
• not bioaccumulative, but humans and animals are exposed at high levels especially through direct contact and water contamination 
• human health effects include endocrine disruption (estrogen-enhancing and testosterone-blocking), thyroid disease, and increased childhood allergies 
• safer alternatives are alcohol based products 
• triclosan and triclocarban are often unnecessary because they are not proven to be any more effective than traditional cleaning products. 
• increased use also potentiates risk for microbial resistance 

3. Flame Retardants 

• class includes PBDEs, brominated and chlorinated-containing chemicals (mostly organhalogens)
• added to products to meet safety standards established in the 1970s
• mostly used in electronics, wires/cables, polyurethane foam, building materials, furniture, and some baby/children products
• when materials that contain flame retardants burn, more toxic soot is released
• flame retardants are semi-volatile meaning they are released into the air which cases particulate matter to settle in dust à increases risk for toddlers d/t hand-to-mouth behaviors 
• human health effects are cancer, immunosuppression, delayed neurodevelopment, endocrine disruption, learning disabilities, ADHD, and infertility 
• no evidence suggests these chemicals improve fire safety 
• regrettable substitutes were put into place without proper safety and efficacy testing (example: firemaster 550 is possibly linked to obesity and anxiety) 

4. Bisphenols and Phthalates 

• these chemicals are dangerous because only a small amount can cause permanent harm due to endocrine disruption
• found in food, soil, air, and water which increases human exposure rates 
• Bisphenols include chemicals like BPA and BPS, which make plastic harder and clearer
• this class of chemicals is used in products like eyeglasses, water bottles, baby bottles, epoxy resins, and thermal paper 
• chemicals leach into products and are directly ingested or are inhaled via dust
• the adverse effects or BPA are numerous: reproductive harm, thyroid disease, immunosuppression, metabolic disorders (obesity, Type I DM), spontaneous abortion, childhood obesity/asthma, and neurodevelopmental issues 
• the alternative BPS may be equally as harmful 

• Phthalates make plastic more flexible and fragrances last longer, which contributes to their widespread use in personal care products, household products, and building materials 
• humans are exposed through many routes: skin absorption, inhalation, and absorption
• prenatal exposure has been linked with incomplete testicular descent, hypospadias, obesity, early breast development, and asthma
• we currently do not have enough data/research to know if the alternatives are safer 
• humans rely heavily on plastics in our everyday lives, so to reduce risk we should use glass whenever possible, avoid receipts, and demand labeling of products 

5. Organic Solvents: 

• purpose and function is to dissolve and disperse materials, act as a carrier, cleaning/stripping agents, and mixers 
• examples include the following:
• hydrocarbon solvents: petroleum distillates and mineral spirits
• chlorinated solvents: paint strippers and dry cleaning chemicals 
• oxygenated solvents: nail polish, nail polish remover, janitorial cleaners, personal care products 
• cyclosiloxanes: dry cleaning chemicals, cosmetics/personal care products, and conditioners 
• humans are exposed through inhalation of volatile vapors as well as through water pollution 
• these chemicals are neurotoxic, nephrotoxic, hepatotoxic, carcinogenic, and cause contact dermatitis/reproductive toxicity 
• the environment is also impacted by these chemicals through ozone and water pollution 
• scientists are currently researching safer alternatives to limit human exposure

6. Some Heavy Metals

• naturally occurring in the environment and never breakdown (meaning they are bioaccumulative in humans)
• interact with oxygen and acid 
• readily conduct heat 
• some metals are beneficial to human health, whereas others are toxic even at low levels 
• toxic metal examples include: lead, arsenic, mercury, chromium, and cadmium
• found in products such as gasoline (prior to late 1970s), paint, treated wood, toys, tattoo inks, beads, blinds, lipsticks, protein drinks, mascara*, fluorescent light bulbs*, and chicken/hog feed* (*these products unintentionally had metals added to them) 
• lead's effect on human health: attaches to RBCs, replaces calcium in bone, neurotoxic, crosses placenta, developmental deficits, kidney failure, etc. 
• arsenic's effect on human health: binds to RBCs, skin lesions, cancer, paresthesia, anemia, vascular disease, etc. 
• to reduce human exposure better recycling of metals should occur and safer alternatives should be used as metals are mostly unnecessary in everyday products