Skin irritations

Although unpleasant, skin irritation, which manifests itself as redness (erythema) and/or swelling (oedema) is not a major problem, as once the source of irritation is removed the effect diminishes. Most fragrance ingredients are classed as mild or moderate irritants when in an undiluted form only, so the low levels found in consumer products are unlikely to be a serious source of irritation. 

Aliphatic diisocyanates can have strong, adverse skin irritation effects and two are well known for this problem, namely dicyclohexylmethane diisocyanate (H12MDI) (Desmodur W by Bayer) and hexamethylene diisocyanate (HDI). Usually care in handling and good hygiene prevents undue problems. Occasionally a more serious effect has been observed in one instance a chemical worker exposed her face to the hot vapour of dicyclohexylmethane diisocyanate and within 24 h her head had swollen to 20% of its original size and characteristic red spots with a white centre were present over the exposed area. Recovery took place slowly over a period of 3 weeks with cortisone-type ointment treatments. Her central nervous system was also affected and took some months to become normal. This was a very unusual and unique incident and is recorded to show that occasionally the unexpected human response can occur with diisocyanates. 

For some isocyanates the continuous estimation of the room air concentration is necessary together with local estimations for limited periods. These short duration measurements, in partieular, enable faults in technical safety or leaks to be demonstrated and corrected. 

The growing importance of isocyanates, especially TDI and MDI, in industry means that more and more people work with these highly reactive products. Isocyanate manufacturers consider it important to carry out further research into the biological activity of this group of substances, and to inform the users of the possible health risks if they are not handled properly. 

The British Rubber Manufacturers Association (BRMA) publishes an operating and medical code of practice Isocyanates in Industry and the United Kingdom Health and Safety Executive publishes Isocyanates Toxic Hazards and Precautions, Environmental Hygiene No. 16 (1979). Additionally all isocyanate manufacturers provide free and excellent literature pertaining to the handling and use of diisocyanates. 

The following specific precautions should be taken in the handling of isocyanates. In general, the handling of isocyanates in open vessels should be avoided as much as possible. For example, liquid isocyanate preparations should be transferred to vessels by pumps or by vacuum technique. Methods of dip-leg transfer by means of air pressure applied to a supplier s drum are not acceptable since escapes of vapour may occur. Fully enclosed systems of handling should be used wherever practicable. 

The skin irritancy of anionics can be diminished by the addition of positively charged materials such as protein hydrolysates (Taves, 1986) or long-chain amine oxides that interact with the anionic and decrease its tendency to adsorb onto the skin, or by polymers that interact with them (Chapter 5, Section 1B5) to reduce the CMC and, consequently, the concentration of monomeric anionic surfactant (Goddard, 1994), since it is the latter that produces the skin irritation. 

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Crystalline solid m.p. 35-36 "C, b.p. 154--156 C, prepared by oxidizing A,A -dicycIo-hexylthiourea with HgO in carbon disulphide solution, also obtained from cyclohexylamine and phosgene at elevated temperatures. Used as a mild dehydrating agent, especially in the synthesis of p>eptides from amino-acids. Potent skin irritant. 

Nacconate 100 A lachrymatory liquid b.p. 25l°C. Manufactured from phosgene and 2,4-diaminotoJuene. Used for preparing polyurethane foams and other elastomers by reaction with polyhydroxy compounds. Produces skin irritation and causes allergic eczema and bronchial asthma. 

Cl2C = CCl CCl =CCl2. Colourless viscous liquid b.p. 210-211 C. Principally used as a dispersant material for obtaining i.r. spectra of solids in mulls. Skin irritant. 

Note. The 2 4-dinitroclilorobenzene must be handled cautiously it is a skin irritant. If any touches the skin, wash it immediately with methylated spirit. 

GA UTION. Styrene dibromide is a skin irritant and all contact with It should be avoided. Rubber gloves should be used in its preparation. 

Caution-. Use rubber gloves during the work-up, the allenyne alcohol probably is a skin irritant. 

The xylenes are mildly toxic. They ate mild skin irritants, and skin protection and the cannister-type masks are recommended. The oral LD q value for rats is 4300 ppm. The STEL for humans is 150 ppm. Xylenes show only mild toxicity to fish, and the threshold limit for crop damage is 800—2400 ppm. Biodegradation with activated seed is slow, and sewage digestion is impaired by 0.1% concentrations. In the event of a spih, oil-skimming equipment, adsorbent foam, and charcoal maybe used for cleanup. 

Propargyl alcohol is a primary skin irritant and a severe eye irritant and is toxic by all means of ingestion all necessary precautions must be taken to avoid contact with Hquid or vapors. The LD q is 0.07 mL/kg for white rats and 0.06 mL/kg for guinea pigs. 

Butynediol is a primary skin irritant and sensitizer, requiring appropriate precautions. Acute oral toxicity is relatively high LD q is 0.06 g/kg for white... 

Health nd Safety Factors. Butenediol is noncorrosive and stable under normal handling conditions. It is a primary skin irritant but not a sensitizer contact with skin and eyes should be avoided. It is much less toxic than butynediol. The LD q is 1.25 mL/kg for white rats and 1.25—1.5 mL/kg for guinea pigs. 

Health and Safety Factors. Butanediol is much less toxic than its unsaturated analogs. It is neither a primary skin irritant nor a sensitizer. Because of its low vapor pressure, there is ordinarily no inhalation problem. As with all chemicals, unnecessary exposure should be avoided. The LD q for white rats is 1.55 g/kg. 

Health and Safety Factors. Butyrolactone is neither a skin irritant nor a sensiti2er however, it is judged to be a severe eye irritant in white rabbits. The acute oral LD q is 1.5 ml,/kg for white rats or guinea pigs. Subacute oral feeding studies were carried out with rats and with dogs. At levels up... 

The lower vinyl ethers do not appear to be skin irritants or sensitizers. 

With respect to acute toxicity, based on lethaHty in rats or rabbits, acryhc monomers are slightly to moderately toxic. Mucous membranes of the eyes, nose, throat, and gastrointestinal tract are particularly sensitive to irritation. Acrylates can produce a range of eye and skin irritations from slight to corrosive depending on the monomer. 

The cured 2-cyanoacryhc ester polymers are relatively nontoxic. Oral doses of 6400 mg/kg failed to kill laboratory rats. Mild skin irritation was observed with guinea pigs, but there was no evidence of sensitization or absorption through the skin (15). 

Material Acute oral LD q tats, s/V Eye irritation, rabbits Primary skin irritation, rabbits... 

Primary human skin irritation of tetradecanol, hexadecanol, and octadecanol is nil they have been used for many years ia cosmetic creams and ointments (24). Based on human testing and iudustrial experience, the linear, even carbon number alcohols of 6—18 carbon atoms are not human skin sensitizers, nor are the 7-, 9- and 11-carbon alcohols and 2-ethylhexanol. Neither has iudustrial handling of other branched alcohols led to skin problems. Inhalation hazard, further mitigated by the low vapor pressure of these alcohols, is slight. Sustained breathing of alcohol vapor or mist should be avoided, however, as aspiration hazards have been reported (25). 

Formaldehyde causes eye, upper respiratory tract, and skin irritation and is a skin sensitizer. Although sensory irritation, eg, eye irritation, has been reported at concentrations as low as 0.1 ppm in uncontrolled studies, significant eye/nose/throat irritation does not generally occur until concentrations of 1 ppm, based on controlled human chamber studies. Odor detection has commonly been reported to occur in the range of 0.06—0.5 ppm (133—135). 

Health and Safety Factors (Toxicology). No special precautions are necessary in the handling of malonic acid beyond normal safe handling measures. Due to its acidity malonic acid is classified as a mild irritant (skin irritation, rabbits). The LD q value (oral, rats) for malonic acid is 2750 mg/kg. Transport classification RID/ADR, IMDG-Code, lATA/lCAO not restricted. 

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. 

Health and Safety Factors. Handling of cyanoacetic acid and cyanoacetates do not present any specific danger or health hazard if handled with the usual precautions. Cyanoacetic acid is classified as a moderate irritant (skin irritation, rabbits) and has an LD q (oral, rats) of 1500 mg/kg. Methyl and ethyl cyanoacetate are both classified as slight irritants (skin irritation, rabbits) and have an LD q (oral, rats) of 3062 and 2820 mg/kg, respectively. Transport classification cyanoacetic acid RID/ADR 8 IMDG-Code 8 lATA/ICAO 6.1. Methyl and ethyl cyanoacetate RID/ADR 6.1 IMDG-Code 6.1 lATA/ICAO 6.1. 

Health and Safety Factors. Malononitrile is usually available as a soHdifted melt in plastic-Hned dmms. Remelting has to be done carefully because spontaneous decomposition can occur at elevated temperatures, particularly above 100°C, in the presence of impurities such as alkaHes, ammonium, and 2inc salts. Melting should be carried out by means of a water bath and only shordy before use. Occupational exposure to malononitrile mainly occurs by inhalation of vapors and absorption through the skin. Malononitrile has a recommended workplace exposure limit of 8 mg/m, an LD q (oral, rats) of 13.9 mg/kg, and is classified as slight irritant (skin irritation, rabbits). Transport classification RID/ADR 61, IMDG-Code 6.1, lATA/ICAO 6.1. 

Dinitrochlorobenzene is used primarily in the manufacture of azo dyes other areas include the manufacture of fungicides, mbber chemicals, and explosives. It is produced by Eastman Kodak Company and Sandoz Chemical Corporation and its bulk fob price is 2.73/kg. 2,4-Dinitrochlorobenzene is more toxic than nitrobenzene. It is an extremely powerful skin irritant and must be handled with great cate. 

Phosphoms(V) sulfide is a mild skin irritant and may cause dermatitis in sensitive individuals. The primary health ha2ard results from the Hberation of hydrogen sulfide after contact with moisture. Contact with moisture also forms phosphoric acid. A secondary ha2ard is the formation of sulfur dioxide when phosphoms(V) sulfide bums. The oral LD q of in rats is 389 mg/kg the OSHA standard time-weighted average (TWA) is 1 mg /m (33). 

Derivatives. Scopoletin [92-61-5] (6-methoxyumbeUiferone) (38) occurs, for example, in Solanaceae as a growth factor in plants. Primin [15121 -94-5] (2-methoxy-6-pentyl-l,4-benzoquinone) is a skin irritant isolated from Primula ohconica. Versicolin [4389 4-0]... 

Skin Irritation. Monoethan olamine and monoisopropan olamine, being strongly alkaline, are skin irritants, capable of producing serious injury in concentrations of 10% or higher upon repeated or prolonged contact. Occasional short contact, assurning the material is thoroughly washed off, should have httle adverse effect. 

Diethanolamine, diisopropanolamine, and isopropan olamine mixtures are less irritating to the skin than MEA and MIPA however, any one of them may produce severe skin irritation, even mild bums, if contact is prolonged or frequently repeated. Occasional short contact should not result in more than slight irritation. Undiluted triethanolamine and triisopropan olamine are slightly to moderately irritating to the skin. A bum may result from prolonged and repeated contact. Short occasional contact and solutions of less than 10% concentration are unlikely to cause more than very slight irritation, if any. 

In studies of the polymerization kinetics of triaUyl citrate [6299-73-6] the cyclization constant was found to be intermediate between that of diaUyl succinate and DAP (86). Copolymerization reactivity ratios with vinyl monomers have been reported (87). At 60°C with benzoyl peroxide as initiator, triaUyl citrate retards polymerization of styrene, acrylonitrile, vinyl choloride, and vinyl acetate. Properties of polyfunctional aUyl esters are given in Table 7 some of these esters have sharp odors and cause skin irritation. 

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