Toxicity of polymers

Several TLC related reviews have appeared, namely on polymers and oligomers [523], and on the toxicity of polymer additives [524]. Wilson and Morden [525] have reported practical applications of TLC. Applications of TLC have been described in a monograph [526]. 

Table 1. The data on biocidicity and toxicity of polymer derivatives of AG, MAG and...

Green N K, Herbert C W, Hale S J, et al. (2004). Extended plasma circulation time and decreased toxicity of polymer-coated adenovirus. Gene Ther. 11 1256-1263. 

The new nanocomposite materials can be produced having improved physical, thermal and flammability properties with controlled durability, by having various types of nanoparticles. However, the degradation durability and toxicity of polymer-nanoparticles systems have to be evaluated for each nanoparticle with different polymers matrix under different environmental conditions for realizing the potential of nanomaterials. 

Higher molecular weight polyethylene usually shows a low toxicity [2]. The degradation of the molecules results in formation of low molecular weight fragments and even of monomers. The reciprocal dependence of the toxicity of polymers of a certain homologous series on their molecular weight has been reported [2]. 

Poly(lactic acid) (PLA) has gained tremendous attention in the past decade due to its desirable characteristics, namely, degradability under biotic or abiotic conditions, non-toxicity of polymer and degradation by-products, and adequate mechanical properties for use in select applications. Copolymerization of naturally occurring L-lactic acid with various polyester-forming monomers may potentially yield materials that display novel physical properties while maintaining reasonable degradation profiles. This approach also offers economical and environmental benefits due to the fact that L-lactic acid can be obtained from renewable resources, such as com. ... 

Acrylic polymers are considered to be nontoxic. In fact, the FDA allows certain acrylate polymers to be used in the packaging and handling of food. However, care must be exercised because additives or residual monomers present in various types of polymers can display toxicity. For example, some acryflc latex dispersions can be mild skin or eye irritants. This toxicity is usually ascribed to the surfactants in the latex and not to the polymer itself. 

In the area of municipal and iadustrial wastewater treatment, the principal environmental issue is the toxicity of residual flocculating agents ia the effluent. Laboratory studies have shown that cationic polymers are toxic to fish because of the iateraction of these polymers with giU. membranes. Nonionic and anionic polymers show no toxicity (82,83). Other studies have shown that ia natural systems the suspended inorganic matter and humic substances substantially reduce the toxicity of added cationic polymer, and the polymers have been used successfully ia fish hatcheries (84—86). Based on these results, the EPA has added a protocol for testing these polymers for toxicity toward fish ia the presence of humic acids (87). The addition of anionic polymers to effluent streams containing cationic polymers to reduce their toxicity has been mentioned ia the patent Hterature (83). 

The self-ignition temperature of PVF film is 390°C. The limiting oxygen iadex (LOI) for PVF is 22.6% (98), which can be raised to 30% ia antimony oxide-modified film (99). Hydrogen fluoride and a mixture of aromatic and aUphatic hydrocarbons (100) are generated from the thermal degradation of PVF. Toxicity studies, ie, survival and time to iacapacitation, of polymers, ceUulosics (101,102), and airplane iaterior materials (103) expose... 

Daylight fluorescent pigments (qv) are considered to be nontoxic. Since they are combinations of polymers and dyestuffs, the combined effect of the ingredients must be taken into account when considering the net toxic effect of these materials. Table 5 gives results of laboratory animal toxicity tests of standard modified melamine—formaldehyde-type pigments, the Day-Glo A Series, and the products recommended for plastic mol ding, Day-Glo Z-series. 

Health and Safety Factors. Animal-feeding studies of DMPPO itself have shown it to be nontoxic on ingestion. The solvents, catalyst, and monomers that are used to prepare the polymers, however, should be handled with caution. Eor example, for the preparation of DMPPO, the amines used as part of the catalyst are flammable toxic on ingestion, absorption, and inhalation and are also severe skin and respiratory irritants (see Amines). Toluene, a solvent for DMPPO, is not a highly toxic material in inhalation testing the TLV (71) is set at 375 mg/m, and the lowest toxic concentration is reported to be 100—200 ppm (72). Toxicity of 2,6-dimethylphenol is typical of alkylphenols (qv), eg, for mice, the acute dermal toxicity is LD q, 4000 mg/kg, whereas the acute oral toxicity is LD q, 980 mg/kg (73). The Noryl blends of DMPPO and polystyrene have PDA approval for reuse food apphcations. 

Nonionic surfactants and phenoUc resins based on alkylphenols are mature markets and only moderate growth in these derivatives is expected. Concerns over the biodegradabiUty and toxicity of these alkylphenol derivatives to aquatic species may limit their use in the future. The use of alkylphenols in the production of both polymer additives and monomers for engineering plastics is expected to show above average growth as plastics continue to replace traditional building materials. 

Polymer Solvent. Sulfolane is a solvent for a variety of polymers, including polyacrylonitrile (PAN), poly(vinyhdene cyanide), poly(vinyl chloride) (PVC), poly(vinyl fluoride), and polysulfones (124—129). Sulfolane solutions of PAN, poly(vinyhdene cyanide), and PVC have been patented for fiber-spinning processes, in which the relatively low solution viscosity, good thermal stabiUty, and comparatively low solvent toxicity of sulfolane are advantageous. Powdered perfluorocarbon copolymers bearing sulfo or carboxy groups have been prepared by precipitation from sulfolane solution with toluene at temperatures below 300°C. Particle sizes of 0.5—100 p.m result. 

Because chloroprene is a flammable, polymerisable Hquid with significant toxicity, it must be handled with care even in the laboratory. In commercial quantities, precaution must be taken against temperature rise from dimerisation and polymerisation and possible accumulation of explosive vapor concentrations. Storage vessels for inhibited monomer require adequate cooling capacity and vessel pressure rehef faciUties, with care that the latter are free of polymer deposits. When transportation of monomer is required, it is loaded cold (< — 10° C) into sealed, insulated vessels with careful monitoring of loading and arrival temperature and duration of transit. 

The chemical industry uses esters for a variety of purposes. Ethyl acetate, for instance, is a commonly used solvent, and dialkyl phthalates are used as plasticizers to keep polymers from becoming brittle. You may be aware that there is current concern about possible toxicity of phthalates at high concentrations, although a recent assessment by the U.S. Food and Drug Administration found the risk to be minimal for most people, with the possible exception of male infants. 

Another concern, is the potential reactivity of 10 as a transfer agent under polymerization conditions (see 3.3.1.1.4).103 Tetramethylsuccinonitrile (9) appears to be essentially inert under polymerization conditions. However, the compound is reported to be toxic and may be a problem in polymers used in food contact applications.1" 30 Methacrylonitrile (MAN) formed by disproportionation readily copolymerizes.7"34 The copolymerized MAN may affect the thermal stability of polymers. A suggestion103 that copolymerized MAN may be a "weak link" in PS initiated with AIBN has been disputed.14... 

With the increasing use of polymers in both the home and the workplace, there seems to have been a change in the nature of fires. Fire brigades now report fires that are shorter and more intense than previously there is also much more smoke and significantly greater amounts of toxic gases. All of these arise from the nature of the polymers being used in everyday life. 

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