Skip to main content
NCBI home page
Environment & Health logoLink to Environment & Health
. 2026 Feb 11;4(6):1073–1082. doi: 10.1021/envhealth.5c00549

Identifying Chemicals of Health Concern in Hair Extensions Using Suspect Screening and Nontargeted Analysis

Elissia T Franklin †,*, Kristin Favela ‡, Radonna Spies ‡, Jacqueline M Ranger ‡, Ruthann A Rudel †
PMCID: PMC13288227  PMID: 42344585

Abstract

Chemical exposures from hair extensions pose a growing public health concern due to their poorly characterized composition and limited regulatory oversight. Extensions are commonly made of human hair, other natural fibers, or synthetic fibers that may be treated with dyes, flame retardants, waterproofing agents, pesticides, antimicrobials, and conditioning agents with hazardous properties. Hair extension use may contribute to exposure and health disparities. We used nontargeted analysis (NTA) to understand the chemical composition of 44 hair samples. We performed suspect screening and NTA using two-dimensional gas chromatography-high-resolution mass spectrometry. We used the Highlight machine-learning platform to annotate detected chemical features by comparing their mass spectra to those of the National Institute of Standards and Technology library. We detected 933 chemical signatures, with 5,275 total detections across all samples. We confirmed and tentatively identified 169 chemicals then classified their potential hazard using structure (e.g., organohalogens) and presence on public chemical lists. Nearly 10% of samples contained hazardous organotin compounds, including some above 0.4% (w/w) tin. Four organotin structures were confirmed with reference standards, and seven structures were solved de novo. The remaining structures are tentatively annotated but unambiguously contain tin or tin and halogens based on the unique isotope patterns and mass defects. Forty-eight chemicals confirmed and tentatively identified in hair extensions were on a hazard list including California’s Proposition 65. To our knowledge, this is the most comprehensive testing of hair extensions publicly reported. Follow-up research to understand exposures and policies to increase disclosure and reduce hazards will reduce health risks.

Keywords: nontargeted analysis, hair extensions, synthetic hair, braiding hair, plastics, organotins, proposition 65

graphic file with name eh5c00549_0004.jpg

graphic file with name eh5c00549_0002.jpg

Introduction

Despite the global hair extension market being projected to surpass $14 billion by 2028, with the United States (U.S.) leading in global imports, the substances in hair extensions remain poorly characterized and regulated. The limited studies on hair extensions suggest that they may be an important source of chemical exposures. Studies demonstrated the release of volatile organic chemicals (VOCs) from common hairstyling practices and detection of metals and some organic chemicals in products, some of which are known to have carcinogenic effects. −

Consumer product use is an important pathway of exposure to hazardous chemicals, though risk assessment and regulation are challenging because of lack of ingredient transparency; insufficient hazard, toxicity, and exposure data; and the difficulty associating exposure with health effect for long latency outcomes. , Research by the U.S. Environmental Protection Agency (EPA) and others recognizes the importance of consumer product use on chemical exposures, and human studies have linked certain exposures with adverse health outcomes. − Compelling examples include formaldehyde in personal care products, − , polybrominated diphenyl ether flame retardants in textiles and furnishings, and widespread consumer and food-related uses of per- and polyfluoroalkyl substances (PFAS) leading to direct exposure and drinking water contamination. − , Despite existing regulatory authority at the U.S. Food and Drug Administration (for cosmetics) and EPA (for other consumer goods), few consumer product chemicals or products have been regulated or restricted by these agencies. In response to this lack of government oversight, individual states have passed laws banning or restricting certain chemicals, for example in children’s products, food packaging, and cosmetics. − Another example is California’s Proposition 65 (Prop 65), which requires warnings to be placed on products if they may expose consumers to certain hazardous chemicals. , For example, warnings about phthalates may appear on plastic lunch boxes, nail polish, and vinyl furnishings. Prop 65 has been shown to encourage manufacturers to reformulate products to avoid product warning labels and to produce safer products. Biomonitoring data have show that exposures to chemicals have gone down after being listed on Prop 65. The Prop 65 hazardous chemicals list includes carcinogens and reproductive and developmental toxicants identified by authoritative entities such as the International Agency for Research on Cancer, the U.S. National Toxicology Program, and the California Office of Environmental Health Hazard Assessment; and this list has been incorporated by reference in other laws in California and several other states.

The cultural significance of hair paired with perceived protective styling drives Black women to be major consumers of these products. Collins et al. showed that more than 70% of Black women wore hair extensions at least once per year compared to less than 10% of Latina, Vietnamese, and White women.

Hair extensions are a likely source of chemical exposures because of intimacy, duration, and practices of use. Extensions are in extended contact with skin, particularly the neck and scalp, including during bathing and showering. It is common practice to heat, boil, and style the hair which can be a source of inhaled volatile or semivolatile constituents or combustion products. , Ingestion of leachable constituents may also occur from mouthing of extensions or hand to extension and hand to mouth contact, especially among children and hair stylists who may provide hair extension services. Many wearers continuously integrate hair extensions when styling, so exposure can be chronic. Thus, individuals wearing hair extensions experience direct and continuous skin contact for extended periods in addition to likely ingestion and inhalation exposures.

Hair extension product packaging and websites rarely disclose chemical composition. Extensions may be made of human hair, other natural fibers, or synthetic fibers and may be treated with dyes, flame retardants, waterproofing agents, pesticides/antimicrobials, and other conditioning agents. Packaging and websites sometimes describe the plastic polymers used to make hair fibers and may also include claims about heat and fire resistance and other claims that may relate to chemical composition. These characteristics may be associated with toxic flame retardants, PFAS, pesticides, and other hazards.

Suspect screening analysis (SSA) and nontargeted analysis (NTA) are useful tools for learning about the qualitative and semiquantitative chemical composition of consumer products. SSA utilizes a chemical library for tentative chemical identification while NTA aims to identify all detected chemicals. − SSA and NTA can overlap with SSA performed using the National Institute of Standards and Technology (NIST) library, for example, and chemicals outside the NIST library characterized in other ways. SSA and NTA studies may also incorporate more traditional targeted analysis to confirm the identity and sometimes the concentration of chemicals discovered.

The software Highlight was designed to enable high-throughput screening and pattern analysis of two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOF-MS) data sets. − Highlight uses a machine-learning algorithm to determine and assign a signal quality score to each feature, and high-quality signals are leveraged in iterative processing to elucidate low abundance features. It has successfully been used in previous studies to evaluate the presence of a wide variety of chemicals in consumer products. ,− High-throughput analysis of chemicals in hair extensions has not been previously reported.

To learn about potentially hazardous exposures from hair extensions, we used two-dimensional GCxGC-TOF-MS, processed data using Highlight, and performed SSA using the NIST library and NTA. Also, Parr oxygen bomb/ion chromatography (IC) was used to analyze total halogens and inductively coupled plasma-optical emission spectrometry (ICP-OES) was used for total tin analysis.

Materials and Methods

Product Selection

We bought 43 commercially available hair products from online and in-store retailers. Products were selected based on social media, blog, and search engine popularity (Google/YouTube, Instagram, TikTok), specified claims (water repellent, flame retardant, nontoxic, etc.), and marketing style (youth-focused, inexpensive, brand representation). Brands that were only available online were purchased from the brand websites. We purchased all other products from local beauty supply retailers in Houston, Texas, in September 2023. Samples were categorized based on fiber type as reported on product packaging. Each fiber type was then classified as synthetic (made of plastic polymers) or bio-based (derived from natural polymers). The final hair sample consisted of donated hair clippings that were pooled and anonymized prior to analysis. No personal or identifiable information was collected, so individual donations were not traceable. This study did not involve human or animal subjects.

Total Halogen Analysis

Samples were assayed for total halogen elements (fluorine, chlorine, and bromine) using a modified EPA SW-86 Test Method 5050 for preparation followed by IC. 0.2 g–0.5 g of each sample was combusted in a stainless-steel sample cup using a Parr Oxygen Bomb (P/N 1106) with approximately 0.3 g of dodecane as a combustion aid. A 10 mL aliquot of 1 mol/L sodium hydroxide (NaOH) was added to the bomb as an absorbing solution. Due to the high levels of halogens being liberated during the combustion, we selected a NaOH solution instead of the weak carbonate/bicarbonate absorbing solution specified in the method to prevent the pH of the absorbing solution becoming highly acidic. After sealing, the bomb was purged with oxygen to remove the inert atmosphere prior to pressurizing to 38–40 atom. The bomb was immersed in a water bath and ignited. The combustion products were quantitatively transferred and further diluted in deionized water for ion chromatography analysis. Three samples were randomly selected to be assayed in duplicate and spiked with targets as positive controls. A method blank was assayed as a negative control.

The analysis was performed by using a Thermo Scientific Dionex DX500 IC system equipped with a conductivity detector. The columns used were a Dionex IonPac AS14 analytical column with an AG14 guard column. A Dionex AERS-500nion self-regenerating suppressor was used. The instrument was calibrated with NIST traceable reference standards for fluoride (SPEX #AS-F9-2Y), bromide (SPEX #AS-BR9-2Y), and chloride (SPEX #AS-CL9-2Y). A calibration curve consisting of six points from 0.1 to 10 mg/L was used along with a solvent blank as a negative control. Samples were diluted to remain within the calibration curve.

GCxGC Sample Preparation and Analysis

We selected gas chromatography to capture volatile and semivolatile compounds that may be in hair extensions and to utilize an established SSA workflow with the NIST library. We do not capture the chemical space accessible only by liquid chromatography.

Each sample was prepared by weighing approximately 100 mg of product and adding 10 mL of dichloromethane. Four samples were selected at random to be extracted and analyzed in duplicate (a bio-based and three synthetic samples). Sodium sulfate (0.5 g) was added as a drying agent. The sample was capped, vortexed for 1 min, and centrifuged at 2000 rpm for 2 min. The organic layer was removed for analysis and not concentrated further. One milliliter was transferred for analysis. Sample extracts and negative controls (dichloromethane solvent blank taken through all preparation steps and dilution blank) were analyzed as-is and further diluted as necessary to mitigate overloaded regions of the chromatogram. All samples were extracted and analyzed in a single batch. Reference standard cocktails including components of method EPA 8270 were assayed along with the samples for retention time and mass spectral confirmation. Supporting Information Table B2 contains a complete list of reference standards. Prior to analysis, deuterated internal standards (1,4-dichlorobenzene-d4, naphthalene-d8, acenaphthene-d10, phenanthrene-d10, chrysene-d12, and perylene-d12) were spiked into all sample extracts and negative controls and reference standards at 1.0 μg/mL to monitor instrument performance. GCxGC-TOF-MS analysis was performed using an Agilent 7890 gas chromatograph coupled to a LECO high-resolution time-of-flight mass spectrometer (LECO, St. Joseph, MI). Instrumental conditions can be found in the Supporting Information.

GCxGC Data Processing

Initial peak finding and integration was performed using LECO’s ChromaTOF commercial software. Subsequent processing utilized the custom-built software package Highlight. Highlight is a third-generation machine-learning software package developed for processing high-resolution GCxGC-TOF-MS data and described elsewhere. − Highlight includes a fully connected artificial neural network and features including chromatographic alignment, multidilution aggregation, background subtraction, unsupervised learning for sample clustering, outlier detection, dimensionality reduction, and association rule learning.

After data collection, ChromaTOF software was used to find and integrate peaks and to identify them based on NIST (2020) library searching. The raw data (.mzml) and initial peak tables (.csv) were exported and then uploaded to Highlight to initiate batch processing. Batch processing occurs in three steps: preprocessing, initial peak grouping, and an iterative data extraction step. In brief, preprocessing consists of loading the batch, defining background samples, and defining retention time and mass accuracy settings. Initial peak grouping groups the mass spectral peaks with a sufficient signal quality score across all samples in the batch. Iteration is accomplished using the Feature Identification using Spectral Hierarchies for Iterative NTA Grouping algorithm. The algorithm uses the initial peak table to select the characteristic fingerprint ions for each peak group. The raw data are evaluated and integrated using the selected fingerprint. Highlight batch processing steps and settings are described further in the Supporting Information.

Chemical annotations were classified by confidence level using a system designed specifically for GCxGC. Confidence level 1 indicates the chemical identification confirmed with a reference standard. Level 2 indicated tentative identification of chemical structure with diagnostic evidence (e.g., accurate mass, isotope pattern, library match). Level 3 indicates the chemical class tentatively identified with uncertainty surrounding the exact structure, chain length, ring substitution pattern, etc. All other signatures were characterized as level 4.

Identification of Potentially Hazardous Chemicals

We used chemical structural features and hazardous chemical lists developed by others to flag potentially hazardous chemicals in hair extensions. We grouped detected chemical signatures into 10 structure-based groups, including 6 hazard-based structural categories (halogenated chemicals, nitroaromatics, phthalates, polyaromatics, and organotins), three other structural categories (aromatic and non-aromatic heteroatoms and other hydrocarbons), and unknown structures. While there may be other detected structures that are also hazardous but not prioritized in these groups, we highlighted these for their carcinogenic and endocrine disrupting activities. For example, organohalogen flame retardants, phthalates, and polyaromatic compounds have been a focus of legislative, regulatory, and voluntary initiatives to identify and reduce exposure sources based on these hazards. Organotins are commonly used to stabilize polyvinyl chloride (PVC) polymer and are classified in the European Union as substances of very high concern. Finally, nitroaromatics are a structural class that was enriched among chemicals that can increase synthesis of estradiol or progesterone, both likely risk factors for breast cancer.

We relied on the following hazardous chemical lists to flag level 1 and 2 chemicals of concern in hair extensions: Carcinogens or reproductive toxicants identified by the state of California under Prop 65, chemicals flagged having a hazard trait or toxicological end point by California’s Safer Consumer Products program (CalSAFER), and potential breast carcinogens or breast cancer relevant chemicals (BCChems) identified by Silent Spring Institute based on their ability to cause mammary gland tumors in experimental carcinogenesis studies or to activate the estrogen receptor or increase estradiol or progesterone synthesispathways known to increase breast cancer risk. We also flagged chemicals listed as flame retardants in the Joint U.S. Consumer Product Safety Commission-U.S. EPA Flame Retardant Inventory because we were interested in whether we would detect flame retardants in the extensions. Finally, because synthetic hair extensions are made of plastic fibers, we also highlighted compounds that are listed in the PlastChem database, and noted if they were classified as Red List (classified as hazardous and not regulated under multilateral environmental agreements), Orange List (classified as less hazardous and/or proposed for regulation), Gray List (no hazard data), and White List (classified as not hazardous). Summaries and visualizations were generated using R version 4.4.0.

Tin Analysis

The four samples with detected organotin compounds were assayed for tin content by ICP-OES using three separate preparation techniques: acid digestion of the matrix (for total tin), a water leachate, and an acid leachate.

Approximately 300 mg of sample was subjected to microwave digestion with 9 mL of nitric acid and 3 mL of hydrochloric acid. The samples were heated to 190 °C in 20 min and held for an additional 15 min. The final digestates were brought to 50 mL with DI water.

The water leachate was intended to simulate a hot shower. It was prepared by taking 1 g of each sample and adding 30 mL of deionized water to a plastic centrifuge tube. The samples were incubated at 40 °C for 60 min and then centrifuged at 2300 rpm for 30 min. The aqueous portion was transferred to another centrifuge tube and then assayed by ICP.

The acid leachate was intended to simulate apple cider vinegar, which is a home remedy employed to prewash artificial hair before wearing. The acid leachate was prepared by taking 1 g of each sample and adding 30 mL of 5% acetic acid in a plastic centrifuge tube. The 5% acetic acid solution was prepared by volumetric dilution using deionized water and glacial acetic acid (Fisher Scientific), resulting in a pH of approximately 3. The samples were held at room temperature for 60 min and then centrifuged at 2300 r/min for 30 min. The aqueous portion was transferred to another centrifuge tube and then assayed by ICP-OES.

For the leachates, negative controls were also prepared and consisted of deionized water and 5% acetic acid taken through the same preparation steps as the samples.

Results and Discussion

Sample Description

Hair extension manufacturers use many fiber types to accommodate a range of styling desires, budgets, and consumer expectations. For example, a common hairstyling practice is to burn or heat synthetic hair to set and seal braids; thus, consumers may choose products labeled as flame retardant or heat resistant. We evaluated 43 hair extensions across nine fiber type categories, some with varying claims that may be related to chemical composition (Table ). The synthetic fiberswhich are plasticswere 16 Kanekalon, 3 Aquatex, 2 Spetra, and 7 Mastermix. Eight additional synthetic hair samples were analyzed that did not identify the fiber type on the label (unspecified).

1. Hair Extensions Tested.

polymer category hair type number of samples chemical related claims
synthetic Kanekalon 16 flame resistant
Aquatex 3 water resistant
Mastermix 7 heat resistant
Spetra 2 antibacterial
toxic-free
chloride-free
unspecified 3 flame resistant
2 heat resistant
2  
1 non-toxic
bio-based banana 2 no polyvinyl chloride
no phthalates
biodegradable
silk 1 hypoallergenic
virgin human 1 100% virgin human hair
mostly unprocessed
raw human 3 100% unprocessed human hair
no synthetic fibers
single donor
Open in a new tab
a

The pooled hair sample is excluded from the table.

b

Green claim.

c

On label as “7A unprocessed”.

d

A full list of claims is provided in the supporting document.

Synthetic fibers are marketed as having varying claims and properties. Kanekalona synthetic fiber with a modacrylic copolymer and vinyl chloridehas a large share of the global synthetic hair market alongside acrylic, polyester, and PVC. In the U.S., modacrylic fibers are regulated to be composed of 35 to 85% by weight of acrylonitrile units. Kanekalon is a proprietary polymer fiber, claiming to mimic human hair while maintaining flame retardant properties, as labeled on all samples. Aquatex is a Kanekalon-based product marketed as a water-repellent modacrylic fiber. All of the Aquatex samples were labeled with water-repellent claims, suggesting the presence of PFAS chemicals that can be used to achieve water-repellency. PFAS are widely regarded as hazardous and are flagged on many hazardous chemical lists such as Prop 65. Spetra is described as an “antibacterial fiber” that claims to be “toxic-free”, “chloride-free”, and contain “no phthalates”. Mastermix is marketed as a blend of human hair (usually about 10%) and undefined synthetic fibers. Nineteen synthetic samples claimed to be flame retardant, three water resistant, nine heat resistant, and three samples made green claims (e.g., No PVC, nontoxic).

The bio-based fibers were 3 raw human, 1 virgin human, 2 banana, 1 silk, and a pooled human hair sample (Tables , S1–S4, and B1). The human hair products were distinctively sold as “virgin” and “raw”, conveying consumer expectations to distinguish how human hair is produced. Virgin human hair is described as processed without using chemicals to dye, bleach, or modify the texture; however, chemical treatments may have been used to enhance shine or conditioning. In contrast, raw human hair is marketed as completely unprocessed, and the purest form of human hair. Each unit is expected to be from a single donor who, in some cases, donated their hair in a temple as a spiritual or religious practice or for financial compensation. The silk samples were eyelash extensions. More details about each product and their claims are provided in the Supporting Information Tables S1–S4.

Total Halogen

Total halogen concentrations in the fiber provided insight into the material composition. Specifically, this measure pointed to polymeric makeup and suggested the presence of certain halogenated flame retardants, plastic fiber coatings, and additives. We measured total fluorine, bromine, and chlorine in all of the samples with reporting limits in the ranges of 10–20, 1,000–2,000, and 10,000–20,000 μg/g, respectively.

We detected chlorine in all of the Kanekalon hair at 223,000–277,000 μg/g (Tables and S5). Flame retardants are of health concern, with many halogenated aromatics and organophosphates included on hazard lists such as Prop 65 or the Registration, Evaluation, Authorisation, and Restriction of Chemicals (REACH) candidate list of substances of very high concern in the EU. Fluorine or bromine was not detected in Kanekalon, suggesting that chlorine may be the only halogen contributing to the flame retardant properties of the fiber.

2. Total Halogen .

hair type relevant claim n mean fluorine(μg/g) mean bromine(μg/g) mean chlorine(μg/g)
Kanekalon flame retardant 16     257,000
Aquatex water repellent 3 461   258,000
Mastermix   7 46.2 (4/7) 34,500 (7/7) 1,530 (1/7)
unspecified flame retardant 3     458,000
heat resistant 2 57.8 50,100  
  2     372,000
virgin human heat resistant 1     4,680
Open in a new tab
a

Spetra, the unspecified fiber labeled as nontoxic (U8), banana, silk, pooled hair, and raw human samples did not have detectable concentrations of halogen and are not included in this table for brevity.

b

Reporting limit range 10–20 μg/g.

c

Reporting limit range 1,000–2,000 μg/g.

d

Reporting limit range 10,000–20,000 μg/g

Fluorine was detected at 419–493 μg/g in Aquatex hair. Although we did not detect any PFAS in a targeted analysis of 40 compounds using EPA Method 1633, this method only includes a few ionic PFAS and does not capture ultrashort-chain PFAS like trifluoroacetic acid, fluorotelomer alcohols, or other neutral PFAS that may have been present. Aquatex and Kanekalon had similar amounts of chlorine, consistent with Aquatex being a Kanekalon-related fiber with fluorinated compounds.

We did not detect fluorine, bromine, or chlorine in Spetra hair, supporting the chloride-free claim.

We detected bromine in all Mastermix hair at concentrations ranging from 25,200 to 44,400 μg/g, suggesting a bromine-containing polymer or flame retardant, or a combination. We detected fluorine in four of the seven Mastermix samples at 31.5–54.7 μg/g. Three of the fluorine-containing samples were colors 1B (“natural” black), and one was 613 (light blonde), while the other colors did not contain fluorine, suggesting that color variation may contribute to this difference. Possibly some colors need thermal, chemical, or weather stabilizers. One Mastermix sample contained chlorine (1530 μg/g), bromine (33,100 μg/g), and fluorine (37.5 μg/g).

The highest concentration of chlorine among all samples (507,000 μg/g) was in one of the three samples with the claim “flame retardant” and this was the only hair tested from this company (Tables S3–S5). Four samples from one manufacturer had chlorine (370,000–436,000 μg/g) and no fluorine or bromine. Interestingly, chlorine concentrations in the two with the flame retardant claims were higher than in those without, suggesting that all four are made with a PVC-type polymer, and the ones with flame retardant claims may also contain chlorinated flame retardants (Tables , S3–S5). A pair of samples from one manufacturer with a heat-resistant claim contained both fluorine and bromine at concentrations of 51.5/64.1 and 47,600/52,600 μg/g, respectively, possibly indicating brominated polymers and flame retardants, and possibly some PFAS. The last unspecified sample was labeled as nontoxic and had no detected halogens (Tables S3 and S5). Overall, concentrations of chlorine and bromine in the unspecified fibers were higher than in other fiber types. It is difficult to predict halogen content in synthetic hair samples that do not disclose fiber types, regardless of claims.

Among bio-based fibers, the virgin human was the only one that contained any detectable halogen, with a chlorine concentration of 4,680 μg/g (Table ). Our findings suggest that some chlorinated compounds are used for treatment or enhancement of virgin hair. Elemental halogens were not detected in any of the five products that had health-related claims and green marketing (2 banana, 2 Spetra, and 1 unspecified fiber).

SSA and NTA of Hair Extracts

Following dichloromethane extraction, GCxGC separation, TOF-MS detection, signature annotation, and averaging replicates, we found a total of 933 chemical signatures and 5,275 individual detections across all samples. A heatplot shows each signature detected in each sample (Figure S1). We classified 18% of the chemical signatures as an identification confidence level of 1 or 2 and another 55% as a confidence level 3 (Table S6). The remaining signatures were classified as unknown structures, or confidence level 4.

Kanekalon, Spetra, and Aquatex had the lowest median number of unique detected signatures (Table S7). We detected the greatest number of unique chemical signatures in a raw human hair sample and the least number of signatures in a Kanekalon sample. The number of chemical signatures detected in each sample represents the complexity of the fiber, as signatures in bio-based fibers include both synthetic and naturally occurring chemicals. Of the unspecified samples, the sample labeled as nontoxic had less than 50 chemical signatures, compared with over 200 signatures found in most other unspecified samples (Table S7). Of synthetic hair types, unspecified fibers had the most total chemicals with confidence levels 1–2, with the sample labeled as nontoxic again having the least number of chemicals compared with other unspecified samples (Table S6 and S7).

The structural categories “other hydrocarbon”, and “other non-aromatic heteroatom” had the most detected chemicals across samples and accounted for the greatest number of chemical signatures (confidence levels 1–3, Table ). Compared to synthetic hair, bio-based fibers generally had more signatures in these categories, which excluded our designated hazardous categories: halogenated chemicals, nitroaromatics, phthalates, polyaromatics, and organotins.

3. Range and Median Values for the Number of Compounds Detected in Signatures with Confidence Levels of 1–3,

hair type value type halogenated aromatic (N = 11) halogenated non-aromatic (N = 19) phthalate (N = 17) nitroaromatic (N = 32) other aromatic heteroatom (N = 86) other hydrocarbon (N = 124) other non-aromatic heteroatom (N = 355)
Kanekalon (N = 16) range 0–2 0–7 0–3 0–3 0–4 7–23 8–29
median 0 5.5 0 1 2 14.5 13
Aquatex (N = 3) range 0–2 7–8   1–3   11–18 10–25
median 2 7 0 3 2 17 20
Mastermix (N = 7) range 0–4 2–3 1–3 0–7 4–16 19–63 3–54
median 1 2 3 1 8 27 12
Spetra (N = 2) range 0–1 0–2   0–1 1–4 22–35 6–9
median 0.5 1 0 0.5 2.5 28.5 7.5
unspecified (N = 8) range 0–5 1–6 0–7 0–10 1–19 29–78 5–92
median 3.5 3 2 3 12 68 82.5
banana (N = 2) range   11–14 1–3   1–6 41–50 124–134
median 0 12.5 2 2 3.5 45.5 129
silk (N = 1) range              
median 1 3 3 4 29 64 74
virgin (N = 1) range              
median 2 8 6 4 14 63 115
raw (N = 3) range 0–4 3–5 8–10 2–8 19–41 77–87 127–181
median 1 3 10 2 28 77 148
pool (N = 1) range              
median 0 2 14 2 18 72 157
Open in a new tab
a

Organotins (N = 23) were detected only in unspecified samples (range = 0–12, median = 12).

b

Polyaromatics (N = 14) were detected only in unspecified samples (range = 0–9, median = 8) and silk (N = 1).

c

Number of unique signatures for the structural category.

d

Number of samples.

We found 11 unique halogenated aromatics, 19 halogenated non-aromatics, and thirty-two nitroaromatics across all of the samples (Table ). Halogenated aromatic signatures (confidence levels 1–3) were detected in all synthetic hair categories, with the most unique signatures detected in the unspecified category. Fourteen unique halogenated non-aromatics were detected in a banana sample and also, six in an unspecified sample. Nitroaromatics were detected in all of the sample categories. Seventeen phthalates were detected across about half of the samples, most abundantly in products made from bio-based fibers, although there were detections in some synthetic fibers as well. Bio-based fibers may have phthalates taken into the fibers while being grown or adsorbed onto the fibers from subsequent treatment with phthalate-containing products. Polyaromatic compounds were detected in unspecified samples, and one was detected on silk. Unknown/unidentified (level 4) chemicals were most commonly detected in unspecified and banana fiber samples (Table S6).

Potentially Hazardous Chemicals in Hair Extensions

Organohalogens and Nitroaromatics

Organohalogens and nitroaromatics were detected in the hair samples (Figure ). Bromomethyl benzene and benzyl chloride were the only halogenated aromatics (level 1 and 2) detected in Kanekalon, Aquatex, and virgin samples, and were both also detected in a raw sample. Benzyl chloride and structurally related chemicals are also detected in most of the unspecified synthetic hair samples. The pesticide cis-permethrin was detected in one of the raw human hair samples, highlighting donor’s past exposures, postdonation treatment for removal of insects, or contamination during the manufacturing process. Among halogenated non-aromatics, we detected chloromethyl octanoate, hexanoate, and many level 3 signatures in banana fiber samples (Figure ). Also, we detected tetrachloroethane in multiple samples.

1.

1

Open in a new tab

Heatplot of estimated abundance for halogenated, phthalate, nitroaromatic, and polyaromatic compounds. Chemicals confirmed at confidence level 1 (*) and tentatively identified at level 2 (**) are represented. Abbreviations: banana (B), silk (L), and virgin (V); other categories are listed in full.

We detected 18 nitroaromatic chemicals (confidence levels 1 and 2), with the greatest number of detections in unspecified and raw hair and scattered detections in Kanekalon, Mastermix, and other bio-based hair samples. We found the carcinogenic dye-related chemical aniline in silk and raw hair samples (Figure ).

Phthalates and Polyaromatic Compounds

We detected five phthalates at confidence levels 1 or 2, mostly in bio-based hair, unspecified samples, and Mastermix. We also detected phthalates in a few Kanekalon samples. Polyaromatic compounds were only detected in the unspecified synthetic hair samples, with none detected in the unspecified sample labeled as nontoxic.

Organotins

Twenty-three organotins were detected in four of the unspecified samples (Tables and S8). Total Sn was measured to estimate concentrations (Table ). These results suggest actual tin abundances above 0.4%. Tin was also measured in water and weak acid hair leachate samples, indicating the potential for leaching under normal use and limited extraction during acid prewashes. Several different organotin compounds were detected, including four with a level 1 identification, seven with a level 2, and 12 with a level 3 (Tables and S8). Dibutyldichlorotin was confirmed in four samples, which is a common additive to stabilize PVC polymers. ,

4. Organotin Compound Identities and Elemental Tin Concentrations in μg/g for Unspecified (U) Fiber Samples (U3, U4, U5, and U6; See Supplemental Information for More Sample Details).
ID method formula CASRN ID level U3 U4 U5 U6
butyltrichlorotin GCxGC-TOF-MS compound identification C4H9Cl3Sn 1118-46-3 1 x x    
dibutyldichlorotin C8H18Cl2Sn 683-18-1 1 x x x x
tributyltin chloride C12H27ClSn 1461-22-9 1 x x    
dimethyldichlorotin C2H6Cl2Sn 753-73-1 1     x x
dibutyltin C8H20Sn 1002-53-5 2 x x    
butyldibromochlorotin C4H9Br2ClSn   2 x x    
dibutylbromochlorotin C8H18BrClSn   2 x x    
butyloctyldibromotin C12H26Br2Sn   2 x x    
methyloctyldichlorotin C9H20Cl2Sn   2     x x
dioctyldichlorotin C16H34Cl2Sn 3542-36-7 2     x x
octylbromodichlororotin C8H17BrCl2Sn   2       x
total tin–acid digestion ICP-OES quantification Sn 7440-31-5   4,480 4,260 637 821
total tin–DI leachate Sn 7440-31-5   1.9 3.0 (<1.1) (<1.1)
total tin–acid leachate Sn 7440-31-5   93 95 (<7.0) (<7.0)
Open in a new tab

Dibutyltin compounds are “severely restricted” in the European Union (EU) and considered substances of very high concern. Most of the use for these chemicals is as a heat stabilizer for PVC. , In the EU, dibutyltin compounds are not permitted in articles for the general public if the concentration in the article is above 0.1% by weight of tin, ,, and the concentrations in some of these extensions exceed this limit (range: 0.06–0.45%). We are not aware of any biomonitoring study to measure organotin exposures in a population and characterize hair extension use. Two published studies detected very little tin in reproductive aged female participants from Iowa and Denmark, and race and ethnicity of these populations are not described. ,

Tributyltin chloride was also confirmed in the hair samples (Table ) along with several related organotins. Tributyltin chloride is a well-known endocrine disruptor that causes changes consistent with metabolic syndrome, lipid disruption, and insulin resistance in experimental animals. Tributyltin chloride has been historically used in marine antifouling paints, but this use is banned because of aquatic toxicity. Dibutyltin compounds have also been shown to cause similar metabolic changes in experimental studies. Other health outcomes that have been reported in toxicology studies include mutations, reproductive and immune system toxicity, and skin sensitization. The EPA, Agency for Toxic Substances and Disease Registry, and World Health Organization have set maximum safe doses in the range of 0.3–5 μg/kg-day, though these do not consider the studies showing metabolic changes. , The EPA risk assessment also notes that dermal irritation has been documented in humans, which may be related to reports of skin irritation (contact dermatitis, scalp disease, and traction alopecia) − from people wearing hair extensions.

Identified Chemicals on Hazard Lists

Across the products analyzed, we found 48 chemicals characterized at confidence levels 1 and 2 on at least one of three hazard lists: Prop 65, CalSAFER, and BCChems (Tables and S9). Of the confirmed and tentatively identified chemicals, 12 were listed on Prop 65. Ninety-one percent of the hair extension samples contained at least one chemical on the Prop 65 list, highlighting the relevance of these products for further assessment under the Prop 65 framework. Of the extensions, one unspecified sample and one Spetra sample, which claimed to be non-toxic and toxic-free, were the only samples to contain no chemicals on a hazard list. The remaining seven unspecified fiber samples had more chemicals on hazardous lists than other synthetic fiber samples, excluding one Mastermix sample, which claims to contain both human hair and synthetic fiber (Tables S10–S12). The other Spetra sample and a Kanekalon sample contained one chemical that was listed as a BCChem (Tables S10 and S11). The two banana fiber samples, which claimed to contain no phthalates, contained two and four chemicals on a hazard list, including bis­(2-ethylhexyl) phthalate (Tables and S13). Four flame retardants were found in both synthetic and bio-based samples: tributyl phosphate, triphenylphosphine oxide, tributyl-phosphine oxide, and 2,4,6-tribromophenol (Table S9). Seventeen BCChems were confirmed and tentatively identified across 36 samples (Table S9).

5. Confidence Level 1 and 2 Carcinogens or Reproductive or Developmental Toxicants Listed by California under Proposition 65 Detected in Hair Samples,
name CASRN Kanekalon (N = 16) Aquatex (N = 3) Mastermix (N = 7) unspecified (N = 7) banana (N = 2) silk (N = 1) virgin (N = 1) raw (N = 3)
bis(2-ethylhexyl) phthalate, 117-81-7 3   7 3 2 1 1 3
benzyl chloride 100-44-7 5 2 2 5     1 1
benzophenone, 119-61-9 7     2   1 1 2
ethane, 1,1,2,2-tetrachloro- 79-34-5 6 1 1 3     1  
dibutyl phthalate b, 84-74-2     5 2   1 1 3
styrene 100-42-5       3        
ethylbenzene 100-41-4       2       1
a-methylstyrene 98-83-9       3        
aniline 62-53-3           1   1
benzene, 1,4-dichloro- 106-46-7       1        
1,3-benzenediamine, 4-methyl- 95-80-7     1          
naphthalene 91-20-3       1        
Open in a new tab
a

Values Represent the Number of Samples in which the Compound was Detected.

b

Chemicals detected in pooled hair samples.

c

Also potential breast carcinogens identified by the Silent Spring Institute.

d

Prop 65 chemicals were not found in Spetra samples and one unspecified sample (not included in table).

We also used the PlastChem database to evaluate differences in the presence of potentially hazardous plastic-related chemicals across the hair samples. Collectively, the unspecified fibers had the highest number of chemicals on the PlastChem Red list, while Spetra fibers had the fewest (Figure S2). In all, 74 chemicals confirmed and tentatively identified across all hair samples were on the Red List, showing hazardous plastic chemicals to be ubiquitous (Table S14).

Strengths and Challenges of This Approach

We demonstrated a novel application of NTA to a previously understudied consumer product with a probability of exposure to users, providing evidence to guide new policies that will better protect health by reducing hazardous chemicals in these products and providing greater transparency. To our knowledge, this is the most comprehensive testing of hair extensions publicly reported and the first evaluation of both synthetic and bio-based hair extensions for hazards. This study represents a significant advance beyond previous analyses, which have been limited to a handful of studies, including measurements of VOCs, metals, and other organics in hair, − VOCs released from heating hair extensions, and biomarkers for VOCs in salon workers.

While our work characterizes a diverse range of compounds and compound classes detected in hair extension products, several areas of uncertainty remain and make it challenging to develop clear health-based guidance about the safety of these products. Over 80% of detected signatures could not be fully annotated due to the lack of availability of analytical standards and mass spectra in library databases for these chemicals, many of which may be widely used in products. Although feasible, the manual identification of chemicals presents challenges due to the volume of data acquired in a high-throughput workflow. We also did not detect chemicals fit only for liquid chromatography–mass spectrometry, including categories of interest like organophosphate flame retardants and many PFAS. Finally, structural alerts and presence on hazard lists are crude ways to define hazard, but data for higher confidence approaches are not available for many chemicals of interest and require new resources.

Future Work

Our findings provide evidence to support a range of next steps to advance health equity. Notably, nearly 10% of our samples contained hazardous organotin compounds, a chemical class not commonly reported in consumer products, and some abundances exceeded the European Union concentration limits. This study represents a qualitative screening of gas-chromatography-compatible organic chemicals. Future work should focus on quantification, especially for the most high-risk chemicals, and aim to identify the source of fluorine for those samples with elevated concentrations of total fluorine. Overall, a more comprehensive and systematic assessment of hazards, coupled with studies to better understand exposure pathways, can shape manufacturers’ and consumer choices and consumer protection policies. For example, California residents can advocate for protection under Prop 65, which requires warnings on products about the presence of listed chemicals, and manufacturers may choose to reformulate to avoid these hazardous chemicals. Currently, lack of ingredient disclosure limits consumers’ ability to choose products without hazardous ingredients. We did find two hair product samples without identified hazard list chemicals in our analysis. We encourage producers to act on these findings by disclosing fiber composition and avoiding hazardous chemicals.

Supplementary Material

eh5c00549_si_001.pdf (2.5MB, pdf)

Acknowledgments

This work was funded by a Beauty Justice Grant from the Environmental Defense Fund and charitable donations to Silent Spring Institute, including the Institute’s Safer Chemicals Program. Study funders had no role in study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication. We used the Nontargeted Analysis Study Reporting Tool during the review of this manuscript (DOIs: 10.1021/acs.analchem.1c02621 and 10.6084/m9.figshare.19763503).

Glossary

Abbreviations

SSA

suspect screening analysis

NTA

nontargeted analysis

NIST

National Institute of Standards and Technology

EPA

United States Environmental Protection Agency

PVC

polyvinyl chloride

Prop 65

California’s Proposition 65

BCChems

breast cancer relevant chemicals

CalSAFER

California’s safer consumer products program

PFAS

per- and polyfluoroalkyl substances

FR

flame retardant

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/envhealth.5c00549.

  • The Supporting Information contains product information for all hair extension samples; label claim identifiers and summary table; instrumental analysis conditions and data preprocessing steps; reference standards used in suspect screening; total halogen results by sample; suspect screening detection statistics across fiber types and samples; estimated abundances and annotations for organotin detections; chemical abundances by fiber category; and hazard and regulatory classifications of detected chemicals (PDF)

The authors declare no competing financial interest.

References

  1. Hair Extension & Wigs Market Outlook, 2028; Bonafide Research, March 2023. https://www.researchandmarkets.com/reports/5775024/hair-extension-and-wigs-market-outlook?srsltid=AfmBOorNKSn5s1iC11_xypDTZw3Ohl4mvqJY5iHXSsa4u3wQf_rCKLbR [Google Scholar]
  2. Hair Extensions Market Size, Share, Competitive Landscape and Trend Analysis Report, by Type, by Fitting Type, by Distribution Channel, by End Use: Global Opportunity Analysis and Industry Forecast, 2021–2031; Allied Market Research, 2023. [Google Scholar]
  3. Auguste D., Miller S. L.. Volatile Organic Compound Emissions From Heated Synthetic Hair: A Pilot Study. Environ. Health Insights. 2020;14:117863021989087. doi: 10.1177/1178630219890876. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Dike Ijere N., Okereke J. N., Ezeji E. U.. Potential Hazards Associated with Wearing of Synthetic Hairs (Wigs, Weavons, Hair Extensions/Attachements) In Nigeria. J. Environ. Sci. Public Health. 2022;06(03):299–313. doi: 10.26502/jesph.96120175. [DOI] [Google Scholar]
  5. Odoh R., Yebpella G., Archibong C., Udegbunam I., Onwuka J.. Comparative Assessment of Heavy Metal Profile of Hair Attachments Marketed in Nigeria. Int. J. Modern Chem. 2013;5(3):181–193. [Google Scholar]
  6. Jackson, L. A. Dangerous Chemicals Were Detected in 100% of the Braiding Hair We Tested. Consumer Reports, Inc 2025, https://www.consumerreports.org/health/wigs-hair-extensions/dangerous-chemicals-detected-in-braiding-hair-cr-tested-a4850978424/ (accessed Sept 02, 2025).
  7. Hall L., Iles A., Morello-Frosch R.. Litigating Toxic Risks Ahead of Regulation: Biomonitoring Science in the Courtroom. Stanf. Environ. Law J. 2012;31(1):3. [PMC free article] [PubMed] [Google Scholar]
  8. Judson R., Richard A., Dix D. J., Houck K., Martin M., Kavlock R., Dellarco V., Henry T., Holderman T., Sayre P.. et al. The toxicity data landscape for environmental chemicals. Environ. Health Perspect. 2009;117(5):685–695. doi: 10.1289/ehp.0800168. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Wambaugh J. F., Rager J. E.. Exposure forecasting - ExpoCast - for data-poor chemicals in commerce and the environment. J. Expo. Sci. Environ. Epidemiol. 2022;32(6):783–793. doi: 10.1038/s41370-022-00492-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Eskenazi B., Chevrier J., Rauch S. A., Kogut K., Harley K. G., Johnson C., Trujillo C., Sjödin A., Bradman A.. In utero and childhood polybrominated diphenyl ether (PBDE) exposures and neurodevelopment in the CHAMACOS study. Environ. Health Perspect. 2013;121(2):257–262. doi: 10.1289/ehp.1205597. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Formaldehyde in Hair Smoothing Products: What You Should Know. U.S. Food and Drug Administration, 2021, https://www.fda.gov/consumers/consumer-updates/formaldehyde-hair-smoothing-products-what-you-should-know (accessed April 01, 2025).
  12. Hair Salons: Facts About Formaldehyde in Hair Products. U.S. Department of Labor, Occupational Safety and Health Administration 2023, https://www.osha.gov/hair-salons (accessed April 01, 2025).
  13. Lamplugh A., Harries M., Xiang F., Trinh J., Hecobian A., Montoya L. D.. Occupational exposure to volatile organic compounds and health risks in Colorado nail salons. Environ. Pollut. 2019;249:518–526. doi: 10.1016/j.envpol.2019.03.086. [DOI] [PubMed] [Google Scholar]
  14. Quiros-Alcala L., Pollack A. Z., Tchangalova N., Desantiago M., Kavi L. K. A.. Occupational Exposures Among Hair and Nail Salon Workers: a Scoping Review. Curr. Environ. Health Rep. 2019;6(4):269–285. doi: 10.1007/s40572-019-00247-3. [DOI] [PubMed] [Google Scholar]
  15. Rodgers K. M., Swartz C. H., Occhialini J., Bassignani P., Mccurdy M., Schaider L. A.. How Well Do Product Labels Indicate the Presence of PFAS in Consumer Items Used by Children and Adolescents? Environ. Sci. Technol. 2022;56:6294–6304. doi: 10.1021/acs.est.1c05175. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Rappazzo K. M., Coffman E., Hines E. P.. Exposure to Perfluorinated Alkyl Substances and Health Outcomes in Children: A Systematic Review of the Epidemiologic Literature. Int. J. Environ. Res. Public Health. 2017;14(7):691. doi: 10.3390/ijerph14070691. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Beesoon S., Genuis S. J., Benskin J. P., Martin J. W.. Exceptionally high serum concentrations of perfluorohexanesulfonate in a Canadian family are linked to home carpet treatment applications. Environ. Sci. Technol. 2012;46(23):12960–12967. doi: 10.1021/es3034654. [DOI] [PubMed] [Google Scholar]
  18. Registry, A. f. T. S. a. D. . Toxicological Profile for Perfluoroalkyls. U.S. Department of Health and Human Services, Public Health Service 2021, https://www.atsdr.cdc.gov/toxprofiles/tp200.pdf (accessed April 01, 2025).
  19. Dodson R. E., Franklin E. T., Zota A. R., Jameson R. L., Flint J. R., Edwards L., Weaver E. B., Shamasunder B.. Formaldehyde and Formaldehyde Releasing Preservatives in Personal Care Products Used by Black Women and Latinas. Environ. Sci. Technol. Lett. 2025;12:1205–1210. doi: 10.1021/acs.estlett.5c00242. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Wicks A., Brady S., Whitehead H. D., Hedman T., Zachritz A., Venier M., Peaslee G. F.. Per- and Polyfluoroalkyl Substances in Reusable Feminine Hygiene Products. Environ. Sci. Technol. Lett. 2025;12(8):924–929. doi: 10.1021/acs.estlett.5c00553. [DOI] [Google Scholar]
  21. FDA Regulation of Cosmetics and Personal Care Products Under the Modernization of Cosmetics Regulation Act of 2022 (MoCRA). Library of Congress, Washington, D.C. 2023, https://www.congress.gov/crs-product/R47826 (accessed April 01, 2025).
  22. Brennan N. M., Evans A. T., Fritz M. K., Peak S. A., von Holst H. E.. Trends in the regulation of per-and polyfluoroalkyl substances (PFAS): a scoping review. Int. J. Environ. Res. Public Health. 2021;18(20):10900. doi: 10.3390/ijerph182010900. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Sharkey M., Harrad S., Abou-Elwafa Abdallah M., Drage D. S., Berresheim H.. Phasing-out of legacy brominated flame retardants: The UNEP Stockholm Convention and other legislative action worldwide. Environ. Int. 2020;144:106041. doi: 10.1016/j.envint.2020.106041. [DOI] [PubMed] [Google Scholar]
  24. California Safe Cosmetics Program. California Department of Public Health, 2022, https://www.cdph.ca.gov/Programs/CCDPHP/DEODC/OHB/CSCP/Pages/About-CSCP.aspx (accessed April 01, 2025).
  25. New York Environmental Conservation Law . § 37–0209: Prohibition on the Use of Perfluoroalkyl and Polyfluoroalkyl Substances in Food Packaging. Legislature, N. Y. S., Ed.; Albany, NY. 2024.
  26. Knox K. E., Dodson R. E., Rudel R. A., Polsky C., Schwarzman M. R.. Identifying Toxic Consumer Products: A Novel Data Set Reveals Air Emissions of Potent Carcinogens, Reproductive Toxicants, and Developmental Toxicants. Environ. Sci. Technol. 2023;57(19):7454–7465. doi: 10.1021/acs.est.2c07247. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Knox K. E., Schwarzman M. R., Rudel R. A., Polsky C., Dodson R. E.. Trends in NHANES Biomonitored Exposures in California and the United States following Enactment of California’s Proposition 65. Environ. Health Perspect. 2024;132(10):107007. doi: 10.1289/EHP13956. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Phthalates . Proposition 65 Warning 2017, https://www.p65warnings.ca.gov/fact-sheets/phthalates (accessed Dec 30, 2024).
  29. Ohayon J. L., Polsky C., Schwarzman M. R.. How a Right-to-Know Law Shifts Industry away from Chemicals of Concern: The Case of California’s Proposition 65. Environ. Sci. Technol. 2025;59(7):3344–3354. doi: 10.1021/acs.est.4c07495. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Polsky C., Schwarzman M.. The Hidden Success of a Conspicuous Law. Ecology Law Quarterly. 2020;47(3):823–886. [Google Scholar]
  31. Collins H. N., Johnson P. I., Calderon N. M., Clark P. Y., Gillis A. D., Le A. M., Nguyen D., Nguyen C., Fu L., O’Dwyer T., Harley K. G.. Differences in personal care product use by race/ethnicity among women in California: implications for chemical exposures. J. Exposure Sci. Environ. Epidemiol. 2023;33:292–300. doi: 10.1038/s41370-021-00404-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Liu J., Jiang J., Patra S. S., Ding X., Huang C., Cross J. N., Magnuson B. H., Jung N.. Indoor Nanoparticle Emissions and Exposures during Heat-Based Hair Styling Activities. Environ. Sci. Technol. 2025;59(32):17103–17115. doi: 10.1021/acs.est.4c14384. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Sobus J. R., Wambaugh J. F., Isaacs K. K., Williams A. J., Mceachran A. D., Richard A. M., Grulke C. M., Ulrich E. M., Rager J. E., Strynar M. J., Newton S. R.. Integrating tools for non-targeted analysis research and chemical safety evaluations at the US EPA. J. Exposure Sci. Environ. Epidemiol. 2018;28(5):411–426. doi: 10.1038/s41370-017-0012-y. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Schymanski, E. L. ; Jeon, J. ; Gulde, R. ; Fenner, K. ; Ruff, M. ; Singer, H. P. ; Hollender, J. . Identifying Small Molecules via High Resolution Mass Spectrometry: Communicating Confidence; ACS Publications, 2014; pp 2097–2098. [DOI] [PubMed] [Google Scholar]
  35. Ulrich E. M., Sobus J. R., Grulke C. M., Richard A. M., Newton S. R., Strynar M. J., Mansouri K., Williams A. J.. EPA’s non-targeted analysis collaborative trial (ENTACT): genesis, design, and initial findings. Anal. Bioanal. Chem. 2019;411:853–866. doi: 10.1007/s00216-018-1435-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Phillips K. A., Yau A., Favela K. A., Isaacs K. K., McEachran A., Grulke C., Richard A. M., Williams A. J., Sobus J. R., Thomas R. S., Wambaugh J. F.. Suspect Screening Analysis of Chemicals in Consumer Products. Environ. Sci. Technol. 2018;52(5):3125–3135. doi: 10.1021/acs.est.7b04781. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. Place B. J., Ulrich E. M., Challis J. K., Chao A., Du B., Favela K., Feng Y.-L., Fisher C. M., Gardinali P., Hood A.. et al. An introduction to the benchmarking and publications for non-targeted analysis working group. Anal. Chem. 2021;93(49):16289–16296. doi: 10.1021/acs.analchem.1c02660. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Hartnett M. J., Watson W. D., Janssen J. A., Hua J., Grossman J., Peng Q., Hartnett P., Favela K. A.. Rapid Screening of Consumer Products by GCxGC-HRT and Machine Learning Assisted Data Processing. J. Am. Soc. Mass Spectrom. 2023;34(8):1653–1662. doi: 10.1021/jasms.3c00107. [DOI] [PubMed] [Google Scholar]
  39. Favela K. A., Hartnett M. J., Janssen J. A., Vickers D. W., Schaub A. J., Spidle H. A., Pickens K. S.. Nontargeted Analysis of Face Masks: Comparison of Manual Curation to Automated GCxGC Processing Tools. J. Am. Soc. Mass Spectrom. 2021;32(4):860–871. doi: 10.1021/jasms.0c00318. [DOI] [PubMed] [Google Scholar]
  40. Johnson P. I., Favela K., Jarin J., Le A. M., Clark P. Y., Fu L., Gillis A. D., Morga N., Nguyen C., Harley K. G.. Chemicals of concern in personal care products used by women of color in three communities of California. J. Exposure Sci. Environ. Epidemiol. 2022;32:864–876. doi: 10.1038/s41370-022-00485-y. [DOI] [PMC free article] [PubMed] [Google Scholar]
  41. Lowe C. N., Phillips K. A., Favela K. A., Yau A. Y., Wambaugh J. F., Sobus J. R., Williams A. J., Pfirrman A. J., Isaacs K. K.. Chemical characterization of recycled consumer products using suspect screening analysis. Environ. Sci. Technol. 2021;55(16):11375–11387. doi: 10.1021/acs.est.1c01907. [DOI] [PMC free article] [PubMed] [Google Scholar]
  42. Module 1 Data Validation Guidelines: Data Validation Procedure for Organic Analysis by GC/MS. United States Department of Defense, Environmental Data Quality Workgroup: 2020. [Google Scholar]
  43. Guidance Document on Hazardous Additive, Non-Polymeric Organohalogen Flame Retardants in Certain Consumer Products. 82 FR 45268. CPSC Docket No; CPSC Consumer Product Safety Commission, 2017. [Google Scholar]
  44. Substance Information: Dibutyltin dichloride, https://echa.europa.eu/substance-information/-/substanceinfo/100.010.610 (accessed Dec 29, 2024).
  45. Borrel A., Rudel R. A.. Cheminformatics analysis of chemicals that increase estrogen and progesterone synthesis for a breast cancer hazard assessment. Sci. Rep. 2022;12(1):20647. doi: 10.1038/s41598-022-24889-w. [DOI] [PMC free article] [PubMed] [Google Scholar]
  46. The Proposition 65 List. California's Office of Environmental Health Hazard Assessment, 2023. [Google Scholar]
  47. Candidate Chemicals List. State of California, https://calsafer.dtsc.ca.gov/cms/search/?type=Chemical (accessed Dec 29, 2024).
  48. Kay J. E., Brody J. G., Schwarzman M., Rudel R. A.. Application of the Key Characteristics Framework to Identify Potential Breast Carcinogens Using Publicly Available in Vivo, in Vitro, and in Silico Data. Environ. Health Perspect. 2024;132(1):017002. doi: 10.1289/EHP13233. [DOI] [PMC free article] [PubMed] [Google Scholar]
  49. Joint US Consumer Product Safety Commission-US Environmental Protection Agency Flame Retardant Inventory. U.S. Environmental Protection Agency, https://comptox.epa.gov/dashboard/chemical-lists/FRFULLLIST (accessed Dec 20, 2024).
  50. Wagner, M. ; Monclús, L. ; Arp, H. P. H. ; Groh, K. J. ; Løseth, M. E. ; Muncke, J. ; Wang, Z. ; Wolf, R. ; Zimmermann, L. . et al. State of the science on plastic chemicals-Identifying and addressing chemicals and polymers of concern. 2024; Vol. 949. [Google Scholar]
  51. Product Lineup. Kaneka Corporation 2024, https://www.kanekalon-hair.com/en/lineup (accessed Dec 30, 2024).
  52. Acrylic and Modacrylic Fibers Production: National Emission Standards for Hazardous Air Pollutants (NESHAP) for Area Sources. U.S. Environmental Protection Agency (EPA), https://www.epa.gov/stationary-sources-air-pollution/acrylic-and-modacrylic-fibers-production-national-emission (accessed Dec 30, 2024).
  53. Vitale A., Bongiovanni R., Ameduri B.. Fluorinated oligomers and polymers in photopolymerization. Chem. Rev. 2015;115(16):8835–8866. doi: 10.1021/acs.chemrev.5b00120. [DOI] [PubMed] [Google Scholar]
  54. European Union Bans Certain Organotin Compounds. European Virtual Institute for Speciation Analysis 2009, https://speciation.net/News/EU-bans-certain-organotin-compounds-;~/2009/06/05/4298.html (accessed Dec 29, 2024).
  55. Commission Decision of 28 May 2009 amending Council Directive 76/769/EEC as Regards Restrictions on the Marketing and Use of Organostannic Compounds for the Purpose of Adapting its Annex I to Technical Progress; Official Journal of the European Union: Brussels, 2009. [Google Scholar]
  56. Gadogbe M., Bao W., Wels B. R., Dai S. Y., Santillan D. A., Santillan M. K., Lehmler H. J.. Levels of tin and organotin compounds in human urine samples from Iowa, United States. J. Environ. Sci. Health, Part A: Toxic/Hazard. Subst. Environ. Eng. 2019;54(9):884–890. doi: 10.1080/10934529.2019.1605779. [DOI] [PMC free article] [PubMed] [Google Scholar]
  57. NTP Research Report on Organotin and Total Tin Levels in Danish Women of Reproductive Age; National Toxicology Program, 2016. [PubMed] [Google Scholar]
  58. Amato A. A., Wheeler H. B., Blumberg B.. Obesity and endocrine-disrupting chemicals. Endocr. Connect. 2021;10(2):R87–R105. doi: 10.1530/EC-20-0578. [DOI] [PMC free article] [PubMed] [Google Scholar]
  59. Chamorro-García R., Shoucri B. M., Willner S., Käch H., Janesick A., Blumberg B.. Effects of Perinatal Exposure to Dibutyltin Chloride on Fat and Glucose Metabolism in Mice, and Molecular Mechanisms, in Vitro. Environ. Health Perspect. 2018;126(5):057006. doi: 10.1289/EHP3030. [DOI] [PMC free article] [PubMed] [Google Scholar]
  60. Harper, C. ; Llados, F. ; Diamond, G. ; Chappell, L. L.. ; Toxicological Profile for Tin and Tin Compounds; Agency for Toxic Substances and Disease Registry, 2005. [PubMed] [Google Scholar]
  61. Provisional Peer-Reviewed Toxicity Values for Mono-, Di- and Tri- Butyltin Compounds. U.S. Environmental Protection Agency, https://cfpub.epa.gov/ncea/pprtv/documents/ButyltinCompounds.pdf 2006.
  62. Dlova N. C., Ferguson N. N., Rorex J. N., Todd G.. Synthetic hair extensions causing irritant contact dermatitis in patients with a history of atopy: A report of 10 cases. Contact Dermatitis. 2021;85:141–145. doi: 10.1111/cod.13825. [DOI] [PubMed] [Google Scholar]
  63. Hwang J. C., Beatty C. J., Khobzei K., Kazlouskaya V.. Allergic contact dermatitis of the scalp: a review of an underdiagnosed entity. Int. J. Women’s Dermatol. 2024;10(3):e167. doi: 10.1097/JW9.0000000000000167. [DOI] [PMC free article] [PubMed] [Google Scholar]
  64. Ahdout J., Mirmirani P.. Weft hair extensions causing a distinctive horseshoe pattern of traction alopecia. J. Am. Acad. Dermatol. 2012;67(6):e294–e295. doi: 10.1016/j.jaad.2012.07.020. [DOI] [PubMed] [Google Scholar]
  65. Rucker Wright D., Gathers R., Kapke A., Johnson D., Joseph C. L.. Hair care practices and their association with scalp and hair disorders in African American girls. J. Am. Acad. Dermatol. 2011;64(2):253–262. doi: 10.1016/j.jaad.2010.05.037. [DOI] [PubMed] [Google Scholar]
  66. Louis L. M., Kavi L. K., Boyle M., Pool W., Bhandari D., De Jesús V. R., Thomas S., Pollack A. Z., Sun A., McLean S., Rule A. M., Quirós-Alcalá L.. Biomonitoring of volatile organic compounds (VOCs) among hairdressers in salons primarily serving women of color: A pilot study. Environ. Int. 2021;154:106655. doi: 10.1016/j.envint.2021.106655. [DOI] [PMC free article] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

eh5c00549_si_001.pdf (2.5MB, pdf)

Articles from Environment & Health are provided here courtesy of American Chemical Society

RESOURCES