Figures (7)  Tables (2)

    • Figure 1. 

      (a) Structures of trihydroxybenzene and (b) the reaction of pyrogallol with oxygen.

    • Figure 2. 

      Synthesis of pyrogallol from (a) gallic acid, (b) para-chlorophenoldisulfonic acid, and (c) cyclohexanol.

    • Figure 3. 

      Potential sources of pyrogallol in the environment.

    • Figure 4. 

      Industrial applications of pyrogallol.

    • Figure 5. 

      Potential pathways of pyrogallol in the environment.

    • Figure 6. 

      Pyrogallol impacts both terrestrial and aquatic organisms.

    • Figure 7. 

      Impacts of pyrogallol in vivo.

    • Concentration of pyrogallol Ref.
      1 - Field study
      Tap water 0.012, 0.066, 0.119 mg/L Rao et al.[37]
      River water 0.012, 0.061, 0.121 mg/L
      Domestic wastewaters 1.19, 2.28, 3.54 mg/L Rajkumar & Kim[38]
      Industrial area 1.15, 2.46, 3.66 mg/L
      Sewage 1.00, 2.38, 3.52 mg/L
      2 - Experimental study
      Fish exposure 1, 5, and 10 mg/L Hamed et al.[13−15]
      Invertebrate exposure 10 mg/L Hamed et al.[17]

      Table 1. 

      Concentration of pyrogallol in various aquatic environments and experimental studies

    • Species Conc. Time Effects Ref.
      C. gariepinus
      		0, 1, 5, 10, 20, 30, 40, 50, 75, and
      100 mg/L      		 96 h No mortality with exposure to 0, 1, 5, 10, and 20 mg/L at 96 h. At 96 h, the mortality rates for exposure to 30, 40, and 50 mg/L concentrations were 20%, 50%, and 75%, respectively. At 75 and 100 mg/L, mortality was 100% after 24 h. [13,15]
      1, 5, and 10 mg/L 15 d • Water quality (dose-dependent):
      DO ↓ (11.5 → 5.9 mg/L), pH ↓ (7.01 → 5.3), Temperature ↑ (26.7 → 28.7 °C)
      • Behavior and feeding:
      ↓ Daily food intake; altered swimming/striking
      • Repulsive behavior: bottom dwelling, reduced movement
      •↓ RBCs, Hb, PCV, MCH, MCHC, thrombocytes, lymphocytes (large and small), monocytes, HCO3−, Na+, Cu2+, Cl−, Ca2+
      •↑ MCV, WBCs, neutrophils, eosinophils, creatinine, uric acid, AST, ALT, G6PDH, glucose, total protein, cholesterol, K+, Fe2+, anion gap, % poikilocytosis, % RBC nuclear abnormalities
      C. gariepinus 1, 5, and 10 mg/L 15 d •↓ Lysozyme activity, immunoglobulin (Ig), phagocytic activity
      •↑ Nitro blue tetrazolium (NBT), IL-1β, IL-6
      • Semi-quantitative histopathological scoring: liver, spleen
      • Liver: melanomacrophages, vacuolated hepatocytes, blood clots, severe architectural distortion, haemorrhage
      • Spleen: inflammatory cell infiltration, shrunken white pulp, ↑ red pulp, enlarged melanomacrophage centers, ellipsoid formations (dose-dependent)      		 [14,69]
      C. gariepinus 1, 5, and 10 mg/L 15 d •↑ Catalase, MDA, hydroperoxides, lipid peroxidation, oxidized proteins, DNA fragmentation
      •↓ SOD activity and total antioxidant capacity (TAC)
      • Semi-quantitative histopathological scoring: intestine, kidney, muscle
      • ↑ Collagen fiber deposition (kidney, muscle, intestine) at 1, 5, 10 mg/L pyrogallol (Masson's trichrome)
      • Significant fibrosis associated with observed histological alterations      		 [15]
      C. gariepinus 1, 5, and 10 mg/L 15 d •↓ Follicle-stimulating hormone (FSH), testosterone, sperm count, spermatocrit
      •↑ Luteinizing hormone (LH), 17β-estradiol
      • Testes: necrosis, spermatozoa loss, vacuolation, thickened basement membrane, hypertrophied seminiferous tubules, melanomacrophage aggregation, distorted tubules
      • Ovary: atretic follicles, degraded yolk globules, deteriorating mature oocytes, ↑ perinucleolar oocytes      		 [14]
      C. gariepinus 1, 5, and 10 mg/L 15 d •↓ Acetylcholinesterase (AChE), nitric oxide (NO)
      •↑ Monoamine oxidase (MAO), aldehyde oxidase (AO) (brain & serum)
      • Brain: neuropile deformities, ↓ Purkinje cells
      • Heart: cardiomyocyte degeneration, ↑ collagen fibers
      • Dose-dependent histopathological alterations      		 [16]

      Procambarus clarkii      		 10 mg/L 15 d •↓ Lysozyme (LYZ), phenoloxidase (PO), acid phosphatase (ACP), acetylcholinesterase (AChE), nitric oxide (NO)
      • Intestine: epithelial disorganization, tissue tearing, necrosis, enlarged lamina propria, disrupted epithelium, connective tissue rupture      		 [17]

      Procambarus clarkii      		 10 mg/L 15 d • Hemocytes: altered granular and semigranular cell counts (vs control)
      •↑ AST, ALT, total protein → hepatopancreatic stress/damage
      •↓ SOD, GSH, TAC; ↑ CAT, MDA → oxidative stress
      • Hepatopancreas: vacuolation, degraded tubules, eosinophilic deposits, hemocytic infiltration, abnormal tubule structure      		 [70]
      Zebrafish (Danio rerio) 100, 50, 20, 10, and 2 nM 5-d post fertilization • High toxicity to zebrafish larvae (even at nanomolar levels): ↓ survival, impaired development, altered behavior
      • Time-dependent toxicity: LC50 ↓ (2.049 μM at 24 h → 0.210 μM at 96 h)
      • Developmental defects: ↓ body length, yolk sac edema, body axis deformities, pigmentation defects, swim bladder defects
      • Neurobehavior: ↓ acoustic response, ↑ visual response → neurological disruption      		 [40]

      Table 2. 

      Pyrogallol toxicity and impacts on aquatic species