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Carbopol® polymers, Pemulen™ polymeric emulsifiers and Noveon® polycarbohil are high molecular weight, cross-linked homopolymers and copolymers of acrylic acid. The first Carbopol polymers, developed in 1958, used benzene as the polymerization solvent. Starting in the 1980s new products and processes using ethyl acetate and ethyl acetate/cyclohexane cosolvents were introduced to enhance product safety.
Carbopol, Pemulen and Noveon polymers are manufactured at a number of locations around the world and sold globally. In Europe, Carbopol and Pemulen polymers are manufactured in Antwerp, Belgium. In the U.S., they are manufactured in Calvert City, Kentucky, and in Asia they are manufactured in Pohang, South Korea. Carbopol, Pemulen and Noveon polymers are not sold directly to consumers. They are sold to consumer product and pharmaceutical companies who use them to formulate their pharmaceutical, cosmetic, homecare and industrial products.
These products are used as thickeners, suspending agents, stabilizers and to control dissolving rates of other ingredients when used to manufacture pharmaceuticals, cosmetics, home and industrial products. They have important properties that make them particularly well-suited for a variety of pharmaceutical applications including use in oral solid and liquid dosage forms, topical gel and cream formulations and bioadhesive formulations. Carbopol, Pemulen and Noveon polymers provide consistent functionality in pharmaceutical applications for: controlled release properties in tablets and capsules, bioadhesion, rheology modification, suspension of insoluble ingredients and emulsification of oil-in-water systems. In pharmaceutical tablets and capsules their use can range from 3% to 30% of the finished product weight.
For personal care applications Carbopol polymers are proven thickeners, suspending agents, rheology modifiers, emulsification agents and stabilizers, utilized in a wide variety of products. Carbopol polymers are typically used at concentrations lower than 1% and offer the flexibility to develop products with a wide range of flow and rheological properties.
Carbopol, Pemulen and Noveon polymers are powders averaging two to seven microns in diameter. They are produced from primary polymer particles of about 0.2 micron diameter. Each primary particle can be viewed as a network structure of polymer chains interconnected by crosslinks. Without the crosslinks, the primary particle would be a collection of linear polymer chains intertwined but not chemically bonded. Linear polymers are usually soluble in polar solvents, such as water, while crosslinked polymers are not.
Crosslinked polymers can swell in water up to 1,000 times their original volume to form a gel. Crosslinked polymers do not dissolve in water but can be dispersed, and at times, appear to be soluble to the naked eye.
Carbopol, Pemulen and Noveon polymers, as a class, have received extensive review and toxicological evaluation. The safety of these products is supported by a history of safe use in drugs, cosmetics and household applications. Some of the Carbopol polymers are used in orally ingested drugs and dietary supplements. In some cases, the products formulated with Carbopol polymers are required to be reviewed by the U. S. FDA prior to marketing. These polymers have also been approved by the U.S. FDA for use in several other pharmaceutical dosage forms.
The Cosmetic Ingredient Review Expert Panel and subsequent toxicology testing have demonstrated a low toxicity and irritation potential of Carbopol products. As a result of this, and the properties offered by the polymers, they have gained wide acceptance in a variety of pharmaceutical, cosmetic and detergent applications. These products have a long history of safe use in pharmaceutical, personal care, and home and industrial products.
The biodegradation, bacterial inhibition and removal of a number of Carbopol polymers from wastewater in water treatment were evaluated in laboratory tests. The Bacterial Oxygen Demand (BOD) for the test materials was determined to be zero following exposure to seed bacteria from a local wastewater treatment plant after being incubated with the seed bacteria for two weeks. Other testing demonstrates that none of the polymers biodegrade or inhibit the bacteria over the concentration ranges tested.
Removal of Carbopol polymers in a wastewater treatment facility was evaluated by testing the sorption of the test material onto the biomass. Because the test concentrations were orders of magnitude higher than expected to occur in treatment facilities, the lower sorption for some test materials at high concentrations was determined to be of questionable significance.
Carbon dioxide (CO2) evolution tests were used to evaluate the ready biodegradability of Carbopol 940 polymer. The test material was considered to be ready biodegradable under the strict terms and conditions of the test.
The aquatic toxicity of Carbopol polymers was evaluated in vertebrate and invertebrate species. Based on the data generated from the testing, Carbopol 934 and 940 polymers are not considered toxic to aquatic organisms and do not require labeling for aquatic toxicity.
When used in pharmaceutical and cosmetic applications, these products are regulated by the individual country's health authority. In the United States, they are regulated by the FDA under the Federal Food, Drug and Cosmetic Act. In Europe, they are regulated under the EU Cosmetics Directive and under the European Medicines Agency. Other regulations such as the ASEAN Cosmetics Direction in Southeast Asia cover appropriate use of these products in these regions.
Noveon AA-1 polycarbophil meets the requirements of the U.S. Pharmacopeia (USP) monograph for Polycarbophil. Carbopol and Pemulen polymers meet the requirements of various Carbomer NF monographs.
Exposure Potential
Based on their expected uses as part of Lubrizol customers' formulated products, these polymers are expected in many cases to be ingested and/or to come into contact with the skin. Once they are formulated, they are not expected to pose an inhalation concern. However, the products can pose an inhalation hazard during manufacturing and formulation. As noted above, the average particle sizes for these products fall into the breathable range.
Information on the safe handling of these products is provided to workers through material safety data sheets. These documents provide a broad range of safety information including hazard warnings and recommendations on exposure controls. They note that engineering controls are needed to control exposures and specify what personal protective equipment is needed.
During the manufacture of these products, engineering controls and work practices are used to minimize exposure. Local exhaust ventilation is used to draw the dust away from workers to prevent routine exposures. Employees working in areas where exposure levels exceed the recommended workplace standard are required to wear an approved respirator equipped with a high efficiency particulate filter.
Worker health is monitored through the Lubrizol Occupational Health Surveillance Program and health studies. An occupational health survey of workers exposed to polyacrylate dust did not find any association with exposure and abnormal chest x-rays or lung functions.
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