Environ Sci Technol: The higher the cotton content, the greater the harm! The school uniform material can enter the bloodstream, but it cannot be drained but there is permanent damage!

At this moment, you are in close contact with per-fluoroalkyl substances and polyfluoroalkyl substances (PFAS)! So do you know what PFAS is? How much impact does it have on health? Why is there PFAS in my child's school uniform?

Before starting this article, in order to facilitate a comprehensive understanding of the environmental and health impacts of PFAS, the protagonist of this article, we recommend a film based on real events: Dark Waters
.
In 1998, when the American lawyer Rob Bilott investigated the unexplained death of livestock, he found that the DuPont chemical perfluorooctanoic acid (PFOA, a type of PFAS) caused serious harm
to the human body and the ecological environment.
As a result, Rob Bilott embarked on a 17-year litigation path challenging the entire fluorine industry
.
The story was made into the movie Dark Waters in 2019
.

How does PFAS, which never decompose, enter the human body? What is the hazard?

PFAS, known as the "chemical that never decomposes", is an artificial organic substance containing strong carbon fluorine bonds, which has been widely used in industrial and daily necessities for more than 60 years
because of its good hydrophobic and oleophobic properties and stability.
PFAS include PFOA, perfluorooctanesulfonic acid (PFOS) and many other compounds
.
Your mobile phones, computers, tablets, cars and other electronic devices, non-stick pans, fast food boxes, oilproof paper, food packaging, tablecloths and napkins and other food-related items, shampoo, dental floss, nail polish, foundation and eye makeup and other washing products, paints, sealants, furniture coatings, mattresses and other household products, raincoats, mountaineering, clothing, curtains, quilts and carpets and other textile products all contain PFAS
.

Figure 1 PFAS life cycle (Source: [1])

Health risk assessment studies divide the routes of exposure to PFAS into 3 categories: oral, respiratory and percutaneous
.
Among them, the PFAS of oral exposure route mainly came from diet and drinking water; PFAS through respiratory exposure is mainly derived from dust and air, and percutaneous PFAS exposure is mainly from clothing and washing
.
PFAS is basically non-degradable in the natural environment, and once it enters the human body, it will even be "inherited" to the next generation
.
A growing number of animal and population studies have shown that PFAS is multi-organ toxic, with known adverse effects including genetic, reproductive, neurological and developmental toxicity, endocrine disruption, liver and heart damage, immune and hormonal disorders, and suspected carcinogenicity
.

Fig.
2 Health effects of PFAS (Source: [1])

North American Studies: School Uniforms Are the Hardest Hit Area for PFAS! Call for increased attention

PFAS is fouling and waterproof, and is used as a raw material in garment manufacturing
.
Clothing also serves as an important source of
PFAS entering the environment and direct human contact.
Children's exposure to PFAS is of particular concern
.
Due to their lower body weight and sensitive developmental periods, exposure to children can lead to greater physical burden and higher health risks
compared to adults.
Previous studies have linked childhood exposure to PFAS to overweight and obesity, neurodevelopmental and behavioural problems, dyslipidemia, immunity (including vaccine response and asthma), renal function, and age at menarche
.
The U.
S.
Centers for Disease Control and Prevention recently reported widespread PFAS in blood samples from children ages 3 to 11, but the source and route are unknown
.

On October 4, 2022, a research team from the University of Notre Dame, Indiana University, the University of Toronto, and the Green Science Policy Institute presented a study entitled "Per-and Polyfluoroalkyl Substances in North American School Uniforms" in Environ Sci Technol (Figure 3) [2].

。 The study found that fluorine was detected in 65% of North American children's textile test samples; The PFAS content in school uniforms is comparable to outdoor clothing, much higher than that of infant textile products; Among all types of school uniforms, the total concentration of PFAS in school uniforms made of 100% cotton is higher than that of school uniforms
made of synthetic fiber materials.

Figure 3 Research results (Source: [2])

The researchers purchased large quantities of school uniforms, outdoor clothing, and infant textiles in the United States and Canada to determine
the total fluorine content and PFAS category and content in the samples.
Based on the assay data, the skin exposure of clothing was calculated, and the amount of PFAS used, absorption pathway, and final destination in children's clothing was analyzed (Figure 4).

Figure 4 Schematic diagram of experimental design (Source: [2])

It turned out that:

01 Fluorine was detected in 65% of the test samples, with the highest content in school uniforms

Fluorine was detected in 65% of the tested products in the range of ND–5,020,000 μg/m2 and a median of 67,200 μg/m2
.
School uniforms with the highest total fluorine content followed, followed by waterproof and windproof outdoor clothing, followed by other products (Figure 5).

Fig.
5 Total fluorine concentration of three types of test products (Source: [2])

02 The PFAS forms in all clothing are dominated by FTOH and FTMAc

Among the three product categories, PFAS is dominated by FTOH and FTMAc, but the composition is different
.
School uniforms were dominated by 6:2FTOH, which accounted for 98% of the total target PFAS concentration; For outdoor clothing and other products, the ingredients were more diverse, with 6:2FTOH contributing less (31% and 65%, respectively), while 6:2FTMAc (22% and 7.
9%, respectively) and 8:2FTOH (26% and 12%, respectively) contributed higher
.
Large amounts of FTMAc and FTOH indicate that these products are treated
with side-chain fluorinated polymers.
Ionic PFAS, including PFCA, PFSA, or FTSA, were detected in all of these products, but accounted for less than 5%
of total PFAS.

03 The higher the cotton content of the school uniform, the higher the PFAS content

Compared to cotton blends or synthetic fabrics, cotton is more hydrophilic and requires additional PFAS treatment to achieve the desired waterproof or stain repellent properties
.
The median total PFAS concentration in uniforms of pure cotton (100% cotton) and cotton spandex (97-98% cotton) was similar, but both were higher than those made of cotton/polyester (about 50%)
.

04 Traditional detection cannot completely determine PFAS, and the true content is more than 1000 times higher

Because fluorinated polymers are not extractable and lack analytical methods and standards, there are large amounts of unknown or unquantifiable PFAS
in common consumer products.
In this study, 49 PFAS were targeted by
TOP assay and hydrolysis treatment.
The average concentration of PFAS increased from 21,600 ng/g to 126,000 ng/g, with concentrations of PFPrA, PFBA, PFPeA, PFHxA, and PFHpA increasing at least 1000-fold
.

05 School uniforms may be an important source of inhaled PFAS for children in North America

School uniforms contain unknown PFAS precursors that can be converted to FTOH, which in turn can be converted to PFCA
.
The high concentration of PFAS in school uniforms can be absorbed by the skin, and there is a possibility of
conversion from FTOH metabolism to PFAA.
The use of PFAS in school uniforms offers greater potential
for direct exposure to children.
25% of school-age children in the United States and Canada spend up to 8-10 hours
a day in contact with the skin in their uniforms.
The estimated daily intake (EDI) for the skin ranged from 0.
0002 to 222 ng/kg bw/day, with a median of 1.
03 ng/kg bw/day
.
There is no uniform standard for the acceptable dose of PFAS for dermal absorption, the European Food Safety Authority (EFSA refers to a total daily tolerable dose of PFAS 0.
63 ng/kg bw/day) and the US EPA provides an oral non-carcinogenic reference dose of 20 ng/kg bw/day
for PFOA and PFOS.

Global consumption of all fluoropolymers is 297,000 tons, with the US market accounting for 22%, equivalent to about 65,000 tons
per year.
About 25 percent of U.
S.
used clothes are exported abroad, especially in low-income countries
.
Eventually, most countries dump these clothes into the environment
as untreated waste.
PFAS is released into water, soil and air through the washing and drying process of laundry, where it is further absorbed by the body; PFAS can also be released
through fiber loss when handling, wearing, washing, and drying treated garments.

The study concluded that many children's products that advertise as "dirt-proof" or "waterproof" do contain high levels of PFAS; School uniforms with high levels of PFAS may be a daily pathway for millions of children to be exposed to these harmful chemicals through inhalation, ingestion and possibly absorption through the skin, and are an important source of release of PFAS into the environment during the washing process and end-of-life phase; The need for antifouling in children's products should be re-evaluated and safe alternatives
without PFAS should be used if consumers deem it necessary.

Resources:

[1] Straková， J.
， Schneider， J.
， Cingotti， N.
et al.
， 2021.
Throwaway Packaging， Forever Chemicals： European wide survey of PFAS in disposable food packaging and tableware.
54 p.

[2] Xia C， Diamond ML， Peaslee GF， et al.
Per- and Polyfluoroalkyl Substances in North American School Uniforms.
Environ Sci Technol.
2022 Oct 4；56(19)：13845-13857.
doi： 10.
1021/acs.
est.
2c02111.
Epub 2022 Sep 21.
PMID： 36129192； PMCID： PMC9535897.