Skin contact

Liquids may get on the skin accidentally, through a spill, or through a job process. Some chemicals will cause an external reaction on the skin, such as a burn or an irritation. Other 

Breathing in toxic dust or vapors is the most difficult exposure method to control. That is because you may inhale a harmful substance without being aware of it. It is hard to take precautions if you do not realize a situation is occurring. 

As nanomaterials may invade living systems by penetrating the epidermal layer of the skin, the handhng of engineered nanomaterials and the use of cosmetic products containing nanomaterials will increase the threat of epidermal exposure. Since large, micrometer-sized particles cannot penetrate healthy skin, their only route is through open wounds and cuts [35]. However, as the size of particles reduces to the nanometer scale, the chance of particle penetration is increased dramatically, and consequently nanometer-sized particles will be more harmful than their micrometer-sized counterparts in the case of skin contact 

It has been shown that 0.5 pm fluorescent dextran beads may penetrate the stratum corneum within 60 min under flexing, whereas 1pm beads could not penetrate [95]. Small-sized nanomaterials, such as fullerene, metal nanoparticles and quantum dots, were able to penetrate the intact skin [83, 96-99], with small-sized quantum dots (15 nm) penetrating deeper (observed in the epidermal region) than the larger (40 nm) quantum dots (observed only in the stratum corneum) during the same period (8h) [98]. Aside from the size of the quantum dots, their shape also seems have a role in skin penetrance, as spherical quantum dots were seen to penetrate the epidermal barrier more easily than eUipsoids [98]. 

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For a chemical to affect health, a substance must come into contact with an exposed body surface. The three ways in which this happens are by inhalation, skin contact, and ingestion, the latter being rare. 

Port-type ted dessert wines require skin contact time to extract the anthocyanins, but the fermentation must be short to retain the sugar level neat the 6—10% level desired. The winemaker cannot always achieve desired composition in individual lots. In order to teach the desired standard, it is necessary to make new lots to enable blending to that standard. The right volume of a tedder, less sweet wine will need to be made to bring to standard a lot with low color and mote sugar, for example, while keeping the alcohol also within the desired limits. 

The U.S. Department of Labor (OSHA) has ruled that an employee s exposure to dimethyl acetamide in any 8-h work shift of a 40-h work week shall not exceed a time-weighted average of 10 ppm DMAC vapor in air by volume or 35 mg/m in air by weight (7). If there is significant potential for skin contact with DMAC, biological monitoring should be carried out to measure the level of DMAC metaboHtes in urine specimens collected at the end of the shift. One industrial limit is 40 ppm DMAC metaboHtes, expressed as AJ-methylacetamide [79-16-3] for individuals, and 20 ppm metaboHte average for workers on the job (8). 

Acetone can be handled safely if common sense precautions are taken. It should be used in a weU-ventilated area, and because of its low flash point, ignition sources should be absent. Flame will travel from an ignition source along vapor flows on floors or bench tops to the point of use. Sinks should be rinsed with water while acetone is being used to clean glassware, to prevent the accumulation of vapors. If prolonged or repeated skin contact with acetone could occur, impermeable protective equipment such as gloves and aprons should be worn. 

Acrolein is highly toxic by skin absorption. Brief contact may result in the absorption of harmful and possibly fatal amounts of material. Skin contact causes severe local irritation and chemical bums. Poly(vinyl chloride) coated protective gloves should be used (99). 

In normal practice, good ventilation to reduce exposure to vapors, splash-proof goggles to avoid eye contact, and protective clothing to avoid skin contact are required for the safe handling of acrylic monomers. A more extensive discussion of these factors should be consulted before handling these monomers (67). 

Skin contact with methanol may present a greater health threat than skin contact with gasoline and diesel fuel and is being evaluated. 

Health Safety. PET fibers pose no health risk to humans or animals. Eibers have been used extensively iu textiles with no adverse physiological effects from prolonged skin contact. PET has been approved by the U.S. Eood and Dmg Administration for food packagiug and botties. PET is considered biologically iuert and has been widely used iu medical iaserts such as vascular implants and artificial blood vessels, artificial bone, and eye sutures (19). Other polyester homopolymers including polylactide and polyglycoHde are used iu resorbable sutures (19,47). 

These salts are corrosive and are to be considered toxic because of the presence of Ag+ ions. The American Conference of Government Industrial Hygienists (ACGIH) (1992—1993) has adopted TWA values of 0.01 mg/m for silver metal and 0.01 mg/m for soluble silver salts. TWA for fluorides as F ions is 2.5 mg/m. The MSDS should be consulted prior to use. Skin contact and inhalation should be avoided. 

Toxicity studies on trifluoroethanol show acute oral LD q, 240 mg/kg acute dermal LD q, 1680 mg/kg and acute inhalation L(ct) Q, 4600 ppmh. Long-term subchronic inhalation exposure to 50—150 ppm of the alcohol has caused testicular depression in male rats, but no effects were noted at the 10 ppm level (32). Although the significance of the latter observations for human safety is unknown, it is recommended that continuous exposure to greater than 5 ppm or skin contact with it be avoided. 

Exposure to PTFE can arise from ingestion, skin contact, or inhalation. The polymer has no irritating effect to the skin, and test animals fed with the sintered polymer have not shown adverse reactions. Dust generated by grinding the resin also has no effect on test animals. Formation of toxic products is unlikely. Only the heated polymer is a source of a possible health hazard (120). 

Olefins, Diolefins, and Acetylenes. Members of this category having up to four carbon atoms are both asphyxiants and anesthetics, and potency for the latter effect increases with carbon chain length. Skin-contact effects are similar to those of paraffins. 

Health nd Safety Factors. Isophorone is considered moderately toxic by ingestion and skin contact. Some rat tumor formation evidence has been found (264), but no demonstration as a human carcinogen has been proven. Isophorone is considered an Environmental Protection Agency (EPA) priority pollutant, and has a permissible acute toxicity concentration of 117, 000 ///L to protect freshwater aquatic life, 12, 900 ///L to protect saltwater aquatic life, and 5, 200 ///L to protect human life (265). Isophorone is mildly toxic by inhalation, but because of its low volatiUty it is not a serious vapor hazard. 

Lithium ion is commonly ingested at dosages of 0.5 g/d of lithium carbonate for treatment of bipolar disorders. However, ingestion of higher concentrations (5 g/d of LiCl) can be fatal. As of this writing, lithium ion has not been related to industrial disease. However, lithium hydroxide, either dHectly or formed by hydrolysis of other salts, can cause caustic bums, and skin contact with lithium haHdes can result in skin dehydration. Organolithium compounds are often pyrophoric and requHe special handling (53). 

Health and Safety Factors. Magnesium hydroxide is not absorbed by the skin. Dry magnesium hydroxide may irritate the eyes, skin, nasal passages, and respiratory tract. Routes of body entry are skin contact, eye contact, inhalation, and ingestion. No LD q values for Mg(OH)2 are available. 

Maleic Anhydride. The ACGIH threshold limit value in air for maleic anhydride is 0.25 ppm and the OSHA permissible exposure level (PEL) is also 0.25 ppm (181). Maleic anhydride is a corrosive irritant to eyes, skin, and mucous membranes. Pulmonary edema (collection of fluid in the lungs) can result from airborne exposure. Skin contact should be avoided by the use of mbber gloves. Dust respirators should be used when maleic anhydride dust is present. Maleic anhydride is combustible when exposed to heat or flame and can react vigorously on contact with oxidizers. The material reacts exothermically with water or steam. Violent decompositions of maleic anhydride can be catalyzed at high temperature by strong bases (sodium hydroxide, potassium hydroxide, calcium hydroxide, alkaU metals, and amines). Precaution should be taken during the manufacture and use of maleic anhydride to minimize the presence of basic materials. 

Health and Safety Factors. Dimethyl malonate and diethyl malonate do not present any specific danger of health ha2ard if handled with the usual precautions. Nevertheless, inhalation and skin contact should be avoided. Dimethyl malonate has a LD q (oral, rats) of 4520 mg/kg and is classified as nonirritant (skin irritation, rabbits). Diethyl malonate has an LD q (oral, rats) greater than 5000 mg/kg and is also classified as nonirritant (skin irritation, rabbits). Transport classification for both esters is RID/ADR 3, IMDH-Code, lATA-ICAO not restricted. 

Acids such as sulfuric, hydrochloric, nitric, and especially hydrofluoric as well as strong alkaUes such as caustic soda and caustic potash are extremely corrosive to animal and vegetable tissue. Extreme caution must be taken to prevent skin contact, inhalation, or ingestion. Violent reactions may occur when dissolving or diluting many of these chemicals with water. 

Workers in the metals treatment industry are exposed to fumes, dusts, and mists containing metals and metal compounds, as well as to various chemicals from sources such as grinding wheels and lubricants. Exposure can be by inhalation, ingestion, or skin contact. Historically, metal toxicology was concerned with overt effects such as abdominal coHc from lead toxicity. Because of the occupational health and safety standards of the 1990s such effects are rare. Subtie, chronic, or long-term effects of metals treatment exposure are under study. An index to safety precautions for various metal treatment processes is available (6). As additional information is gained, standards are adjusted. 

Methanol is not classified as carcinogenic, but can be acutely toxic if ingested 100—250 mL may be fatal or result in blindness. The principal physiological effect is acidosis resulting from oxidation of methanol to formic acid. Methanol is a general irritant to the skin and mucous membranes. Prolonged skin contact with methanol vapor or Hquid can cause dermatitis. Methanol vapor can cause eye and respiratory tract irritation, nausea, headaches, and dizziness. 

Eye and Skin Contact. Some nickel salts and aqueous solutions of these salts, eg, the sulfate and chloride, may cause a primary irritant reaction of the eye and skin. The most common effect of dermal exposure to nickel is allergic contact dermatitis. Nickel dermatitis may occur in sensitized individuals following close and prolonged contact with nickel-containing solutions or metallic objects such as jewelry, particularly pierced earrings. It is estimated that 8—15% of the female human population and 0.2—2% of the male human population is nickel-sensitized (125). 

Handling of soluble uranium compounds requires appropriate clothing to prevent skin contact and eye protection to prevent any possible eye contact. Protective clothing requirements for insoluble uranium compounds should prevent repeated or prolonged skin contact. Eye protection for use in handling insoluble uranium compounds should prevent any possibiUty of eye contact. Respirators should always be worn to prevent inhalation of uranium dust, fumes, or gases (38). 

Properties of other higher a-olefins and those of some commercially significant cycloolefins are given in Table 2. These monomers are fiquids at ambient temperature and pressure. They are highly combustible and can form explosive mixtures with air. The primary health hazards presented by these monomers are associated with inhalation or prolonged skin contact that can cause irritation. 

Oxahc acid is not flammable but its decomposition products, both formic acid and carbon monoxide, are toxic and flammable. Its dust and mist are irritating, especially under prolonged contact. Personnel who handle oxahc acid should wear mbber gloves, aprons, protection masks or goggles, etc, to avoid skin contact and inhalation. Adequate ventilation also should be provided in areas in which oxahc acid dust fumes are present. 

Dusts associated with these oxidising compounds produce caustic irritation of skin, eyes, and nasal membranes. Appropriate protection should be worn when handling. Skin contact should be treated as for any caustic material, ie, flush with water and neutralize. Toxicity is low to moderate and is the same as for the hydroxides. Toxicity of the chlorate is greater than for the peroxides and superoxides, and the chlorate material also causes local irritation. 

Extreme caution must be taken to prevent the possibility of fire when using flammable removers. Extra care must be taken when stripping on location to secure the area of ignition sources. When used on lacquer finishes, the dissolved finish and remover combined are extremely flammable. Natural mbber, neoprene, or other gloves suitable for use with the remover formula must be worn. The effect of skin contact with the remover is limited because there is immediate irritation and discomfort. Canister respirators are available for most petroleum and oxygenate remover solvents. Symptoms of long-term overexposure should be compared to symptoms of the major ingredients in the formula. 

Specially designed impervious suits, eg. Level A suits, are utili2ed by workers handling some rocket fuels and other highly ha2ardous compounds (see Explosives and propellants). Barrier creams are much less effective than gloves for preventing skin contact. 

Propylene oxide is a primary irritant, a mild protoplasmic poison, and a mild depressant of the central nervous system. Skin contact, even in dilute solution (1%), may cause irritation to the eyes, respiratory tract, and lungs. Propylene oxide is a suspected carcinogen in animals. The LC q (lowest lethal concentration by inhalation in tats) is 4000 mg/kg body weight. The LD q (oral) is 930 mg/kg. The LD q (dermal) is 1500 mg/kg. The TWA (8-h exposure) is 100 ppm and the STEP (15-min exposure) is 150 ppm. 

Potassium forms corrosive potassium hydroxide and Hberates explosive hydrogen gas upon reaction with water and moisture. Airborne potassium dusts or potassium combustion products attack mucous membranes and skin causing bums and skin cauterization. Inhalation and skin contact must be avoided. Safety goggles, full face shields, respirators, leather gloves, fire-resistant clothing, and a leather apron are considered minimum safety equipment. 

Monoethan olamine and monoisopropan olamine may be moderately toxic by absorption through the skin. The other amines are low in toxicity by this route and are not likely to be absorbed in acutely toxic amounts. In the event of skin contact, clothing and shoes should be removed promptly, and the skin thoroughly washed with water. Contaminated clothing should be thoroughly cleaned before reuse shoes and leather products should be discarded. 

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