Table 2.
Synthetic ingredients in shampoo and the associated risk reported.
| Synthetic ingredients | Functions in shampoo formulation | Associated risk reported | References |
|---|---|---|---|
| Sodium Lauryl Sulphate (SLS) and Sodium Laureth Sulphate (SLES) | Surfactant | Caused skin irritation, dry, cracked, and inflamed skin; could provoke slight to moderate allergy reaction at concentrations as low as 0.5–10 %; caused skin dryness was noticed after one-week usage of products with 5 % SLS and 5 % SLES surfactants; caused skin irritation to the stratum corneum layer of the skin; disrupted the skin barrier; disturbed the skin physiology and skin integrity; reduced the stratum corneum layer; resulted in dry, irritated, itchy, and flaky hair scalp; disturbed the balance between commensals and pathogens (i.e. Propionibacterium spp., Corynebacterium spp., and Micrococcus spp.) and resulting in skin disease; increased in sensitisation reaction in seborrheic dermatitis patients; and may lead to the development of benign, premalignant, or malignant tumour, morphological change of epithelium cells, organ toxicity (predominantly heart, liver, lungs, and brain), ophthalmic irritation, cataract formation, carcinogenic effect, and hair loss upon long term exposure. |
[[7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17]] |
| Cocamidopropyl Betaine (CAPB) | Surfactant | Increased the prevalence rates of allergic contact dermatitis among young children after exposure to baby shampoos containing CAPB; cosmetic-allergic patients experienced scalp itching, inflammation on the ears, neck, and forehead, and developed eczema on the face and neck; and caused dermatological sensitisation upon exposure to impurities in CAPB, such as 3-dimethylaminopropylamine (DMAPA) and amidoamine (AA). |
[[18], [19], [20], [21], [22]] |
| Ethylene oxide (EtO) | Sterilant | Increased in the risk of breast and lymphohematopoietic cancer; exerted a genotoxicity effect and increased in prevalence of mortality; and potentially form macromolecular adducts with nucleic acids and proteins and causes mutation. |
[[23], [24], [25]] |
| Alkanolamines: Triethanolamine (TEA) Diethanolamine (DEA) Monoethanolamine (MEA) Cocamide diethanolamine (CDEA) |
Surfactants, Emulsifying agents pH adjusters |
Caused skin sensitisation; developed occupationally and dermatitis and skin sensitivity upon exposure; resulted in carcinogenicity effect with continuous exposure of DEA, even at low doses; and caused choline deficiency and resulted in irreversible changes in hippocampal function, including altered long-term potentiation and memory. |
[6,[26], [27], [28], [29], [30], [31], [32], [33], [34], [35]] |
| Ethylenediaminetetraacetic acid (EDTA) | Sequestering agents | Developed recurrent pruritic erythema on the scalp, neck, and face upon exposure to cosmeceutical products containing 0.1 % and 1 % disodium EDTA. | [36] |
| Formaldehyde | Preservative | Caused allergic contact dermatitis; and resulted in carcinogenicity, toxicity, and genotoxicity effects after prolong exposure. |
[[37], [38], [39]] |
| Parabens: Methylparaben Ethylparaben, Propylparaben Butylparaben |
Preservative | Caused contact allergic dermatitis; caused breast cancer in females; reduced fertility in males; and increased the prevalence of obesity, gestational diabetes mellitus, adipogenesis, necrosis, collagen degradation, risk of malignant melanoma, skin cancer. |
[[40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52]] |
| Selenium sulphide | Anti-dandruff | Increased sebum excretion; and caused scalp discolouration and dysplasia of hair roots in young children and adults; exerted a toxic effect on the hair root papillae; and caused alopecia (baldness) and fragile hair. |
[[53], [54], [55], [56]] |