Benzene skin absorption

Phloroglucinol (1,3,5-Trihydroxy benzene, 1,3,5-Trioxy-benzol in Ger). C6H3(OH)3,mw 126.11, white to yellowish crysts mp 200—209° when heated slowly 212—217° when heated rapidly bp, sublimes with decompn. SI sol in w, sol in ale and eth. Combustible. Can be prepd by fusion of resorcinol with caustic soda, or by reduction of trinitrobenzene. It is highly toxic. by ingestion, inhalation and skin absorption, and is a strong irritant to skin and mucous membranes Refs 1) Beil 6,1092, (545) [1075]... 

Direct contact with the liquid may cause erythema and vesiculation prolonged or repeated contact has been associated with the development of a dry, scaly dermatitis or with secondary infections. Some skin absorption can occur with lengthy exposure to solvents containing benzene and may contribute more to toxicity than originally believed, but the dermal route is considered only a minor source of exposure for the general population. ... 

The 2003 ACGIH threshold limit value-time-weighted average (TLV-TWA) for benzene is 0.5 ppm (1.6mg/m ) with a TLV STEL of 2.5ppm (8mg/m ) and an Al-confirmed human carcinogen designation and a notation for skin absorption. 

A 44-year-old male worker experienced a large skin area exposure to a mixture of CAC, benzene, and xylidine. The worker was put under a shower within 5 minutes of the accident, but shortly thereafter he began to have respiratory difficulties and experienced an apparent grand mal seizure. The patient was still comatose 2 years after the accident. Burns caused by the chloroacetyl chloride were believed to have enhanced skin absorption of the other two chemicals, although the relative contribution of the three chemicals to the... 

The rate of absorption of ethyl benzene through the skin of the hand and the forearm in human subjects was 22-33 mg/cm /hour, indicating that skin absorption could be a major route of uptake of liquid ethyl benzene. ... 

Note Moderately polar, weakly hydrogen bonding solvent, heavy liquid gradually decomposes to acquire a yellow color, air and light will accelerate this decomposition nonflammable commercial product is often stabilized by the addition of 3 to 4% (mass/mass) alcohols highly toxic by ingestion, inhalation, and skin absorption soluble in alcohols, organohalogen compounds, hydrocarbons, benzene, and many oils incompatible with many alkali and alkaline earth metals. Synonyms tribromomethane. 

Note Nonpolar solvent soluble in alcohols, ethers, chloroform, benzene, and most fixed and volatile oils insoluble in water nonflammable extremely toxic by inhalation, ingestion, or skin absorption carcinogenic incompatible with allyl alcohol, silanes, triethyldialuminum, and many metals (e.g., sodium). Synonyms tetrachloromethane, perchloromethane, methane tetrachloride, Halon-104. 

Note Polar solvent soluble in alcohols, ether, benzene, and most oils usually stabilized with methanol to prevent phosgene formation flammable and highly toxic by inhalation, ingestion, or skin absorption narcotic carcinogenic incompatible with caustics, active metals, aluminum powder, potassium, sodium, magnesium. Synonyms trichloromethane, methane trichloride. 

Note Nonpolar hydrocarbon solvent mild, gasoline-like odor soluble in hydrocarbons, alcohols, organic halides, acetone, benzene flammable moderately toxic by inhalation, ingestion, or skin absorption, may be narcotic at high concentrations reacts with oxygen (air) at elevated temperatures decomposes upon heating incompatible with strong oxidants. Synonyms benzene hexahydride, hexameth-ylene, hexanaphthene, hexahydrobenzene. 

Studies conducted in vivo in humans and in vitro using human skin indicate that benzene can be absorbed dermally. The data show that dermal absorption is not as substantial as absorption following inhalation exposure to benzene vapor or oral exposure. The movement of a substance through the skin to the blood occurs by passive diffusion and has been described mathematically by Fick s law. However, this is an oversimplification of the process of skin absorption various factors (e.g., interaction of benzene with molecules within the skin) affect the transport of the solvent through the skin (Loden 1986). 

Benzene in air was rapidly absorbed through the skin of hairless mice that were attached to respirators to avoid pulmonary uptake of the benzene vapors (Tsuruta 1989). The rate of absorption of benzene through the skin increased linearly with dose. The skin absorption rate for 200 ppm was 4.11 nmol/cm2/hour (0.31 pg/cm2/hour) at 1,000 ppm the rate was 24.2 nmol/cm2/hour (1.89 pg/cm2/hour) and at 3,000 ppm the rate was 75.5 nmol/cm2/hour (5.90 pg/cm2/hour). The skin absorption coefficient was 0.619 cm/hour. 

Based on data for skin absorption of benzene vapors in mice and occupational exposure data, Tsuruta (1989) estimated the ratio of skin absorption rate to pulmonary uptake to be 0.037 for humans. Dermal absorption could account for a relatively higher percentage of total benzene uptake in occupational settings where personnel, using respirators but not protective clothing, are exposed to high concentrations of benzene vapor. 

Several in vivo and in vitro studies conclusively demonstrate that benzene can be absorbed through human skin (Blank and McAuliffe 1985 Franz 1984 Susten et al. 1985 Tsuruta 1989). In general, skin absorption is considered a minor source of concern in the occupational environment as it occurs at a much lower rate and extent compared with benzene absorption through the respiratory system (OSHA 1989). However, benzene absorption through the skin as a result of benzene contamination in rubber solvents is a major route of exposure in tire building operations (Susten et al. 1985). Benzene is an irritant to the skin and, by defatting the keratin layer, may cause erythema, vesiculation, and dry and scaly dermatitis... 

Carbon tetrachloride is colorless, heavy, non-flammable liquid with a characteristic odor. It has a boiling point of 78 Celsius, and a melting point of -23 Celsius. Carbon tetrachloride is insoluble in water, but miscible with alcohol, benzene, chloroform, ether, and carbon disulfide. Carbon tetrachloride is a potential poison, and inhalation, ingestion, and skin absorption should be avoided at all cost. Carbon tetrachloride may be a carcinogen. It is prepared on an industrial scale by the chlorination of methane, but can be conveniently prepared by reacting chlorine with carbon disulfide in the presence of iron fillings the carbon tetrachloride is recovered by distillation. 

Aliphatic EC5-EC8 Fraction. In vitro studies with human skin indicate that the permeability of /7-hexane through skin was about 100-fold lower than the permeability of benzene, suggesting that hydrocarbons in this fraction may have a low potential for skin absorption (ATSDR 1999b). 

Properties Colorless, mobile liquid becomes yellowish under the action of light and air. Fruitlike odor (high dilution). Decomposed by water. Attacks brass but not iron (dry). D 1.742 (14C), bp 156C (decomposes), fp —65C, coefficient of thermal expansion 0.0011, vap d 6 (air = 1.29), volatility 20,000mg/m3(20C), vap press 2.29 mm Hg (21.5C). Soluble in alcohol, benzene, ether, and water. Derivation Chlorination of ethyl arsenious oxide. Hazard Toxic by ingestion, inhalation, and skin absorption strong irritant. 

Benzene (Aldrich Chemical Company, Inc. or EM Science) was purified by distillation from sodium benzophenone ketyl. CAUTION Benzene is harmful as a vapor and by skin absorption, and it should always be handled in a well-ventilated hood. Chronic exposure may cause fatal blood disease. 

Most of the alkane, alkene, and alkyne hydrocarbon compounds are considered to be flammable as their major hazard, and the toxicity is considered as moderate to low. The vapors are more likely to be asphyxiant than toxic. TLVs range from 50 ppm for hexane to 300 ppm for octane. Decane is listed as having a narcotic effect. Many of these hydrocarbons are found in mixtures, and it will be necessary to look at the Material Safety Data Sheets (MSDS) to obtain toxicity information on particular mixtures. Benzene, toluene, and xylene are aromatic hydrocarbons. They are considered highly toxic and human carcinogens. Benzene has a TLV of 0.1 ppm in air, according to the NIOSH Guide 1997 Addition, and an STEL of 1 ppm. The OSHA STEL is 5 ppm and a PEL of 1 ppm. Toluene is toxic by ingestion, inhalation, and skin absorption. The TLV for toluene is 100 ppm in air. Xylenes are toxic by... 

Properties Paie yei. to amber translucent solid si. tuq)entine odor and taste sol. in alcohol, benzene, ether, glacial acetic acid, oils, carbon disulfide insol. in water m.w. 302.46 dens. 1.07-1.09 soften, pt. (R B) 78 C m. p. 100-150 C flash pt. 187 C anionic Toxicobgy May be harmful by inh., ing., or skin absorption may cause eye/skin irritation may cause contact dermatitis may cause sensitization by inh., skin contact TSCA listed Precaution Combustible incompat. with strong oxidizing agents Hazardous Decomp. Prods. CO, CO2 emits toxic fumes under fire conditions... 

Properties Colorless clear liq., benzene odor sol. in alcohol, benzene, ether, acetone, chloroform, petrol, ether, ethyl acetate misc. with most org. soivs. very si. sol. in water m.w. 92.13 dens. 0.866 (20/4 C) vapor pressure 36.7 mm Hg (30 C) m.p. -94.5 C b.p. 110.7 C flash pt. (CC) 4.4 C ref. index 1.4967 (20 C) KB value 105 Toxicology ACGIH TLV/TWA 100 ppm STEL 150 ppm LD50 (oral, rat) 7.53 g/kg, (skin, rabbit) 12,124 mg/kg toxic by ing., inh., IP, and skin absorption irritant to eyes, skin, respiratory tract severe dermatitis on direct contact ing. may cause lung aspiration overexposure by inh. may cause CNS excitation/depression high cones, may cause paresthesia, vision disturbances, dizziness, nausea, headache, narcosis, death experimental teratogen. 

Empiricai CsHioO Formuia (CH3)2C6H30H Properties M.w. 122.17 Commercial mixt. wh. cryst. solid sol. in aq. alkali, oxygenated and aromatic soivs., mostorg. soivs., alcohol, chloroform, ether, benzene si. sol. in water dens. 1.02-1.03 (15 C) m.p. 20-76 C b.p. 203-225 C Toxicoiogy LDLo (oral, man) 5 g/kg poison toxic by ing., skin absorption TSCA listed Precaution Combustible Hazardous Decomp. Prods. Heated to decomp., emits acrid smoke and irritating fumes Uses Disinfectant solvent for wire enamels pharmaceuticals insecticides fungicides herbicides plasticizers rubber chemicals ... 

Lipophilic chemicals are absorbed most easily (for example, benzene). These can include liquid solvents or solvents having low vapor pressure. "" Vapors absorbed by dermal uptake can significantly contribute to the body burden as a result of the whole body exposure e.g. 1-2 %ofxylene or toluene, up to 5-10% l-methoxypropane-2-ol. For other substances, much higher skin absorption rates were measured after the whole body exposure 2-methoxyethanol up to 55 %, 2-ethoxy-eflianol up to 42 %. ... 

The major route of exposure to benzene is inhalation through the lungs of benzene vapors, however skin absorption of benzene has been shown to be significant depending on the circumstances of the exposure such as time of contact between the benzene and the skin. Benzene absorption, as other solvents, through the skin is enhanced if the skin condition is altered by either disease or loss of skin or cracking of the skin. The dermal absorption of benzene deserves much more attention than previously described in various texts of toxicol-... 

Therefore, workers who are exposed to solvents containing benzene should be evaluated for skin absorption dosimetry, in addition to other sources such as inhalation, to address the range of levels of exposure. 

Dermal (skin) absorption is a significant hazard for a number of volatile substances. These include aromatic compounds such as benzene and toluene nitro-compounds such as nitrobenzene, trinitrotoluene and nitro-propane several insecticides and herbicides hydrogen cyanide and organo phosphates. Protective clothing can minimize risks except where splashing and adsoprtion into cloth concentrates exposure to the skin. 

---