Flame retardants pose exposure and health risks

Most flame retardant (FR) chemicals used in products like car seats are not strongly bound to the fabric or foam they are added to, so they easily migrate out and become airborne via dust. Human exposure may occur through breathing or ingesting dust and even through the skin.

A number of FRs are known endocrine disruptors and some are linked to cancer. Other FRs are lacking in toxicity information. Many FRs contain chlorine or bromine (these are called halogenated FRs because chlorine and bromine are halogens) and don’t break down easily in the environment. Chemical persistence can lead to bioaccumulation, the buildup of a substance in people and animals.

Although the historically used brominated FR chemicals called PBDEs have been phased out due to health concerns, we continue to find bromine in a large portion of children’s car seats.  Decabromodiphenyl ethane, or DBDPE, for example, is common in vehicle interiors and was found in this year’s study of children’s car seats.1 DBDPE is highly persistent and bioaccumulative and exhibits developmental and other types of toxicity.2,3

Phosphorus-based FRs (PFRs) can be made without any halogens and have increased in popularity as the health and environmental concerns about halogenated FRs have grown. Triphenyl phosphate (TPHP) is one example of a widespread PFR that is used in some car seats. While eliminated from the body more quickly than other FRs, TPHP is nevertheless found extensively in the environment and accumulates in breast tissues.4 It exhibits hormonal and developmental toxicity.5–7  

 

Fluorinated “forever chemicals” pose exposure and health risks

For the first time in the Ecology Center’s series of car seat studies, we are reporting the likely use of per- and poly-fluorinated alkyl substances (PFAS) on the fabrics of children’s car seats.

PFAS encompass a class of chemicals used, among other applications, to make fabrics water- and stain-resistant. Fluorine is a halogen, so PFAS are halogenated chemicals. Even more so than brominated FRs, PFAS are highly stable and don’t break down easily. In fact, the incredibly strong carbon-fluorine bond gives some PFAS chemicals their reputation as “forever chemicals.”

When PFAS chemicals enter the human body— and virtually every human tested has PFAS in their blood— the chemicals build up in the liver and kidneys and may contribute to elevated cholesterol, immune problems, thyroid disease, kidney cancer and testicular cancer.8  

The original processing chemicals (called C8 or “long-chain” PFAS) used for Teflon™ cookware coatings and Scotchgard™ fabric treatments have been phased out in the U.S. Yet new, closely related substances have taken their place. The newer PFAS processing chemicals for nonstick and stain-proofing are called C6 (or “short-chain”). C6 chemicals are marketed as safe because they don’t build up in the body as efficiently as C8, but new research suggests C6 may nevertheless present a significant health risk.

PFAS in fabrics can easily enter the body through the skin and inhalation. Are children exposed to a significant amount of PFAS from a car seat? The answer is still uncertain. But a recent study by the Commission for Environmental Cooperation9 (CEC), a collaboration of the three North American countries, sheds some light. The study detected PFAS in all waterproof baby mats, pads, and blankets tested and nearly half of bibs tested. The researchers used artificial saliva and mouthing simulations as well as artificial sweat and abrasion simulations to test the migration of PFAS. The Commission found that nearly one half of PFAS present in bibs and other children’s items transferred in the saliva simulation, and one-fifth transferred in the sweat simulation.7

A particularly worrisome finding from the CEC study was that the newer-generation C6 PFAS chemicals more readily migrated into sweat and saliva than the original C8 chemicals.

While infant and child exposure to PFAS from car seat use is the most apparent concern, the manufacturing and disposal— landfilling or incineration— of the chemicals are highly problematic. The entire lifecycle of PFAS releases chemicals of concern into our water and air.

 

Chemicals added to products must undergo toxicological assessment

Chemical hazard assessments should be completed on all FRs and other additives prior to their use in products. One option is Clean Production Action’s GreenScreen® For Safer Chemicals. This tool uses authoritative lists and trained assessors to determine the hazard profile of a substance. GreenScreen assessments for each of the major FRs found in 2018 and 2016 children’s car seats are in the tables below.  

 

Phosphorus Flame Retardants

 
Chemical Name GreenScreen Assessment Score Human Hazards Environmental Hazards
Ammonium polyphosphate 68333-79-9 Benchmark 3: Use but still opportunity for improvement
  • Moderate skin irritation/corrosivity
  • Very high persistence
PMMMPs: Cyclic phosphonates 41203-81-0, 42595-45-9 Benchmark unknown
  • Unknown
  • Unknown
RDP: Resorcinol bis(diphenyl phosphate) 125997-21-9 Benchmark 2: Use but search for safer substitutes
  • Moderate developmental toxicity
  • Moderate endocrine activity
  • Moderate neurotoxicity - repeated exposure
  • Moderate eye irritation/corrosivity
  • Very high acute and chronic aquatic toxicity
  • High bioaccumulation
  • Moderate persistence
TBEP: Tris(2-butoxyethyl) phosphate 78-51-3 Possible Benchmark 1: Avoid
  • High endocrine activity
  • High skin sensitization
  • Very high persistence
TEHP: Tris(2-ethylhexyl) phosphate 78-42-2 Possible Benchmark 1: Avoid
  • High to moderate endocrine activity
  • High eye and skin irritation/corrosivity
  • Very high acute aquatic toxicity
  • High persistence
TEP: Triethyl phosphate 78-40-0 Benchmark unknown
  • High systemic toxicity
  • High eye irritation/corrosivity
  • Moderate reproductive toxicity
  • Moderate acute mammalian toxicity
  • Very high persistence
  • Moderate terrestrial ecotoxicity
TPHP: Triphenyl phosphate 115-86-6 Benchmark 2: Use but search for safer substitutes
  • High endocrine activity
  • Moderate acute mammalian toxicity
  • Moderate carcinogenicity
  • Moderate endocrine activity
  • Moderate systemic toxicity from repeated exposure
  • Moderate neurotoxicity from single exposure
  • Moderate eye irritation/corrosivity
  • Very high acute and chronic aquatic toxicity
  • Moderate terrestrial ecotoxicity
 

 

Brominated Flame Retardants

 
Chemical Name GreenScreen Assessment Score Human Hazards Environmental Hazards
Brominated polystyrene 88497-56-7 Likely Benchmark 1: Avoid
  • High endocrine activity
  • Very high persistence, bioaccumulation, and toxicity
DBDPE: Decabromodiphenyl ethane 84852-53-9 Benchmark 1: Avoid
  • High developmental toxicity
  • High endocrine activity
  • Moderate carcinogenicity
  • Moderate reproductive toxicity
  • Very high persistence, bioaccumulation, toxicity
HBCD: Hexabromocyclodecane 25495-98-1 Likely Benchmark 1: Avoid
  • High reproductive toxicity
  • High developmental toxicity
  • High endocrine activity
  • Very high persistence, bioaccumulation, and toxicity
  • High chronic aquatic toxicity
TBBPA: Tetrabromobisphenol A 79-94-7 Likely Benchmark 1: Avoid
  • High reproductive toxicity
  • High endocrine activity
  • High carcinogenicity
  • Moderate developmental toxicity
  • Moderate eye irritation/corrosivity
  • Moderate acute mammalian toxicity
  • Very high acute and chronic aquatic toxicity
  • Very high persistence, bioaccumulation, and toxicity
TBC: Tris(2,3-dibromopropyl isocyanurate 126-72-7 Likely Benchmark 1: Avoid
  • High carcinogenicity
  • High endocrine activity
  • Moderate mutagenicity
  • Moderate reproductive toxicity
  • Moderate acute mammalian toxicity
  • Moderate systemic toxicity from repeated exposure
  • Very high acute aquatic toxicity
  • Very high persistence, bioaccumulation, and toxicity
 

 

Other Flame Retardants

 
Chemical Name GreenScreen Assessment Score Human Hazards Environmental Hazards
Antimony Trioxide 1309-64-4 Benchmark 1: Avoid
  • High systemic repeat dose toxicity/organ effects
  • Moderate carcinogenicity and mutagenicity
  • Moderate reproductive toxicity
  • Very high persistence
  • High acute aquatic toxicity
  • Moderate chronic aquatic toxicity
Melamine 108-78-1 Possible Benchmark 1: Avoid
  • Moderate carcinogenicity
  • High to moderate endocrine activity
  • Very high to high persistence

 

References

1.           Besis, A., Christia, C., Poma, G., Covaci, A. & Samara, C. Legacy and novel brominated flame retardants in interior car dust – Implications for human exposure. Environmental Pollution 230, 871–881 (2017).

2.           Smythe, T. A. et al. Impacts of Unregulated Novel Brominated Flame Retardants on Human Liver Thyroid Deiodination and Sulfotransferation. Environ. Sci. Technol. 51, 7245–7253 (2017).

3.           Nakari, T. & Huhtala, S. In vivo and in vitro toxicity of decabromodiphenyl ethane, a flame retardant. Environmental Toxicology 25, 333–338 (2010).

4.           Kim, U.-J. & Kannan, K. Occurrence and Distribution of Organophosphate Flame Retardants/Plasticizers in Surface Waters, Tap Water, and Rainwater: Implications for Human Exposure. Environ. Sci. Technol. 52, 5625–5633 (2018).

5.           Zhang, Q. et al. Potential Estrogenic Effects of Phosphorus-Containing Flame Retardants. Environ. Sci. Technol. 48, 6995–7001 (2014).

6.           Isales, G. M. et al. Triphenyl phosphate-induced developmental toxicity in zebrafish: Potential role of the retinoic acid receptor. Aquatic Toxicology 161, 221–230 (2015).

7.           Hendriks, H. S. & Westerink, R. H. S. Neurotoxicity and risk assessment of brominated and alternative flame retardants. Neurotoxicology and Teratology 52, 248–269 (2015).

8.           Agency for Toxic Substances and Disease Registry. An Overview of Perfluoroalkyl and Polyfluoroalkyl Substances and Interim Guidance for Clinicians Responding to Patient Exposure Concerns. (2018).

9.           CEC. Furthering the Understanding of the Migration of Chemicals from Consumer Products - A Study of Per- and Polyfluoroalkyl Substances (PFASs) in Clothing, Apparel, and Children’s Items. 201 (Commission for Environmental Cooperation, 2017).

         
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