Methylparaben (Methyl 4-hydroxybenzoate) CAS 99-76-3

Methylparaben (Methyl 4‑hydroxybenzoate) – Versatile Preservative for Food, Cosmetics, and Pharmaceuticals

Basic Information

• CAS Number: 99-76-3

• Molecular Formula: C₈H₈O₃

• Molecular Weight: 152.15 g/mol

• Appearance: White crystalline powder

• Melting Point: 125–128°C

• Solubility: Slightly soluble in water (≈2.5 g/L at 25°C); freely soluble in alcohol, propylene glycol, and oils

Overview
Methylparaben (methyl p‑hydroxybenzoate) is a widely used antimicrobial preservative in food, cosmetic, and pharmaceutical products. Its effectiveness against a broad spectrum of bacteria, yeasts, and molds, combined with good water‑solubility and compatibility with many formulation ingredients, has made it a standard choice for preservation. It is often used in combination with other parabens (ethyl, propyl, butyl) for synergistic activity and extended spectrum.

Biochemical Mechanisms and Metabolism

• Penetration: Methylparaben can penetrate the skin barrier, especially when damaged.

• Metabolism: In the body, it is rapidly hydrolyzed to p‑hydroxybenzoic acid and other metabolites, which are excreted in urine.

• Estrogenic activity: Some studies indicate weak estrogenic activity at very high doses in vitro, but clinical relevance in humans remains unclear.

Safety and Side Effects

• Allergic reactions: A small percentage of individuals may experience itching, redness, or contact dermatitis.

• Toxicity: At typical use concentrations (0.1–0.4%), methylparaben is considered safe. Excessive doses may cause irritation.

• Compatibility: In the presence of strong oxidizers, methylparaben may degrade, reducing efficacy and potentially forming by‑products.

Environmental Impact

• Water contamination: Parabens, including methylparaben, can be detected in wastewater after rinsing cosmetic and household products.

• Biodegradation: Methylparaben is readily biodegradable by many microorganisms, reducing the risk of accumulation.

• Aquatic toxicity: At high concentrations, it may have negative effects on aquatic life, but real‑world levels are generally low.

Applications

• Food: Preservative in baked goods, beverages, sauces, and dairy products.

• Cosmetics: Used in creams, lotions, shampoos, makeup, and sunscreens.

• Pharmaceuticals: Preservative in oral liquids, topical ointments, and injectable formulations.

• Industrial: As a biocide in paints, adhesives, and coatings.

Recommended Use
Typical usage levels: 0.1–0.4% in food; 0.1–0.3% in cosmetics and pharmaceuticals (combined with other parabens for maximum efficacy). The concentration should be optimized based on product type, pH, and water activity.

New Developments and Alternatives

• Alternative preservatives: Research is ongoing for compounds with similar efficacy but more favorable safety profiles (e.g., organic acids, plant extracts).

• Encapsulation: Microcapsules and liposomes are being developed to reduce skin contact and improve stability.

• Regulatory alignment: The EU, US, and other regions continue to harmonize labeling, concentration limits, and safety testing protocols for parabens.

Handling and Storage

• Store in a cool, dry, well‑ventilated area, away from light and strong oxidizers.

• Keep containers tightly sealed to prevent moisture absorption.

• Use appropriate personal protective equipment (gloves, safety goggles, dust mask) when handling.

• Avoid inhalation of dust and contact with skin and eyes.

Packaging
Available in 1 kg, 5 kg, 25 kg, and 50 kg containers (bags, drums, or boxes). Custom packaging upon request.

Quality Assurance
Each batch is tested for purity (by HPLC), melting point, and heavy metal content to ensure compliance with food, cosmetic, and pharmaceutical standards.