HormonesMelatonin

Chloroxylenol (PCMX) impairs visual system development and induces circadian rhythm disorders with sleep/wake behavioral abnormalities in zebrafish larvae, which can be ameliorated by melatonin intervention.

Exposure to PCMX at concentrations ≥0.4 mg/L caused ocular malformations and suppressed photoreceptor development in zebrafish larvae, while higher concentrations (≥1.2 mg/L) disrupted circadian clock gene expression and led to daytime hyperactivity and insomnia-like sleep fragmentation at night. Melatonin intervention effectively alleviated the sleep/wake behavioral deficits.

Last updated: Jul 27, 2026•0 RCTs•📖 Read as article →

Evidence Score

Evidence Score24/100
Human RCT☆☆☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Chloroxylenol impairs the visual system, induces visually-mediated behavioral abnormalities and circadian rhythm disorders in zebrafish (Danio rerio).

observational

Man X, Bao Y, Feng X · Comparative biochemistry and physiology. Toxicology & pharmacology : CBP (2026)

Participants: N/A
Duration: Not specified in abstract
Intervention: PCMX exposure at 0.4, 1.2, 2, and 2.8 mg/L; melatonin intervention for sleep/wake deficits
Outcome: Ocular morphology, retinal development, visual-mediated behaviors (image-forming and non-image-forming vision), circadian rhythmic expression of melanopsin and core clock genes, sleep/wake behaviors
Effect Size: N/A
Population: Zebrafish (Danio rerio) larvae

Result:

PubMed: 42442645DOI: 10.1016/j.cbpc.2026.110616

Mechanism Graph

PCMX suppresses key genes regulating photoreceptor proliferation and differentiation
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PCMX disrupts thyroid hormone signaling
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This inhibits photoreceptor development and causes retinal pathology
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Result: Impaired image-forming vision and visuomotor responses, plus disrupted circadian rhythms and sleep/wake behavior

Limitations

  • ⚠Study conducted in zebrafish larvae, not directly translatable to humans or mammals
  • ⚠Only acute exposure effects reported; chronic or low-dose effects not assessed

Frequently Asked Questions

What is PCMX and where is it found?▼

PCMX (p-Chloro-m-xylenol) is a broad-spectrum antimicrobial agent widely used in disinfectants and personal care products, frequently detected in aquatic environments.

Does melatonin help with PCMX-induced sleep problems?▼

Yes, the study found that melatonin intervention effectively alleviated the sleep/wake behavioral deficits caused by PCMX exposure in zebrafish larvae.

What concentrations of PCMX caused visual damage in this study?▼

Ocular malformations were observed at concentrations as low as 0.4 mg/L, with more severe visual impairments at 2 and 2.8 mg/L.

What behavioral changes were seen in PCMX-exposed zebrafish?▼

Zebrafish showed daytime hyperactivity and insomnia-like sleep fragmentation at night, along with impaired visuomotor responses to light-dark transitions.

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References

  1. 1.Man X, Bao Y, Feng X. "Chloroxylenol impairs the visual system, induces visually-mediated behavioral abnormalities and circadian rhythm disorders in zebrafish (Danio rerio).." Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, 2026. PMID: 42442645 DOI: 10.1016/j.cbpc.2026.110616
Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.