Cresols, xylenols and cresylic acids are hazardous substances and dangerous both to people and the environment if handled improperly. Cresols, xylenols and cresylic acid products produced by Sasol Chemicals (USA) LLC are highly versatile materials and are used as intermediates in the manufacture of a wide variety of industrial products such as resins, flame retardants, antioxidants, and coatings. In these and other applications, cresylic acids can be stored, transferred, processed and disposed of safely when proper procedures and safeguards are used.
“Cresol” refers to any of the three isomers of methylphenol (C7H8O) or combinations thereof. “Cresols” commonly refer to a mixture which is predominantly methylphenol but may also contain lesser amounts of other alkylphenols. “Xylenol” is a common name for any of the six isomers of dimethylphenol (C8H10O) or their various combinations. Material which is predominantly dimethylphenol but which also contains ethylphenols and other alkylphenols may be referred to as “Xylenols”. “Cresylic acid” is a generic term referring to various combinations of cresols, xylenols, phenol or other alkylphenols (ethylphenols, propylphenols, trimethylphenols, etc.).
Purpose & Scope
The purpose of this document is to provide information gathered through Sasol’s long experience in the safe handling of cresylic acids. It focuses on basic and practical information about working safely with these substances. Additional references are provided and it is strongly recommended that these and others be consulted prior to working with cresylic acids. Please do not hesitate to contact your regional Sasol office if we can be of assistance in the safe storage, handling, processing and disposal of our products.
The primary dangers posed in handling cresylic acids are those resulting from physical exposure. Cresylic acids are highly corrosive and contact with exposed skin or mucous membranes causes severe burns. These burns progress from an initial whitening of the exposed skin to blackishbrown necroses within 24 hours after exposure. Cresylic acids also exhibit anesthetic properties. Therefore, victims frequently misjudge the extent of their exposure when the initial burning sensation rapidly subsides. This can result in prolonged contact, causing toxic effects in addition to the corrosive damage.
Cresylic acids are readily absorbed through the skin and mucous membranes in liquid or vapor form and act as systemic toxins for which there is no established treatment. Relatively small areas of exposure (e.g. an arm or a hand) can allow sufficient absorption to cause severe poisoning. Progressive symptoms of such poisoning include headache, dizziness, ringing in the ears, nausea, vomiting, muscular twitching, mental confusion, loss of consciousness and, possibly, death from lethal paralysis of the central nervous system. Chronic exposure can lead to loss of appetite, vomiting, nervous disorders, headaches, dizziness, fainting and dermatitis.
The Occupational Health & Safety Administration (OSHA) has established 5ppm or 22 mg/m3 permissible exposure limits (PEL’s) for cresols on an 8-hour time-weighted average basis. OSHA guidelines also indicate that adequate personal protective equipment (PPE) should be employed to avoid skin contact with cresols. Cresylic acids are not listed as carcinogens by OSHA, the International Agency for Research on Cancer (IARC) or the National Toxicology Program (NTP).
Cresylic acids show high acute toxicity towards both fish and aquatic invertebrates and must be prevented from entering surface or ground waters. Depending upon the specific composition, the material may be classified as a marine pollutant. Please refer to the current label and safety datasheet.
Controls for Working with Cresols
Safe storage, handling, processing and disposal of cresylic acids begin long before they ever arrive on-site. Measures necessary to ensure the health and well-being of employees, customers, the community and the environment include the development of effective administrative and engineering controls designed to specifically address the hazards associated with cresylic acids. Personal protective equipment (PPE) is integral to safe handling and should be viewed as the last line of defense against an accidental failure of the administrative and/or engineering controls.
Administrative controls are the foundation of any program designed for safely handling cresylic acids. Every company is unique in how they run their business and establish administrative controls. Those specifically developed for working with cresylic acids should address comprehensive process planning, thorough communication of hazards to employees and extensive training of employees on the proper implementation of all safety measures.
Personal Protective Equipment (PPE)
All personnel who work with or near cresylic acids must use adequate personal protective equipment (PPE). The extent of the potential exposure and consideration of established permissible exposure limits (PEL’s) should dictate the level of protection necessary. Personnel working with or near lab-scale quantities should always wear safety glasses with side-shields or
chemical mono-goggles, chemical-resistant or impermeable gloves, long-sleeved shirts and trousers as a minimum.
Circumstances such as elevated temperature and pressure or vacuum conditions should dictate if more substantial protection is necessary, including face shields, chemically impermeable outerwear, and breathing protection. Personnel transferring larger quantities of cresylic acids, or working in areas where a line-break could result in similar exposure, should always wear full protective equipment.
Physical Exposure – External
The primary dangers involved in working with cresylic acids are the corrosive and toxic effects resulting from a physical exposure. Studies suggest that the severity of the exposure depends more on the magnitude of the exposed skin area than the concentration of cresylic acid. Therefore, the critical factor in dealing with an external physical exposure to cresylic acids is to minimize the extent and duration of the contact. To this end, the immediate response must be thorough flushing of the exposed areas with copious amounts of running water to remove all the cresylic acid in contact with the skin or eyes. Any contaminated clothing should be removed as quickly and carefully as possible during this process to avoid any additional skin contact.
Any exposed areas will have readily absorbed the cresylic acids and may be evidenced by a characteristic whitening of the skin. After thorough flushing with water, a solution consisting of 2 parts polyethylene glycol 400 to 1 part ethanol (PEG/EtOH) should be liberally applied to any affected skin (avoid contact with eyes), allowed to remain 15 to 30 seconds and then flushed away with fresh running water. Continue the cycling of PEG/EtOH and water for at least 15 minutes and then finish with thorough washing with soap and water. This decontamination procedure reduces the severity of the exposure, but does not completely eliminate damage to the skin or toxic effects. Medical attention should be sought as soon as possible.
Spill Containment & Clean-Up
Spill containment and cleanup of cresylic acids should only be performed by properly trained personnel employing an appropriate level of protective equipment as dictated by the extent of the spill. Small to medium spills on land should be surrounded by and absorbed onto inert clay absorbent and transferred to a disposal container. Larger land-spills should be diverted away from waterways, contained with booms, dikes or trenches, and collected in a vacuum truck. Any residual cresylic acids remaining after vacuuming should be cleaned up using the clay absorbent. All soils affected by the spill should be removed and placed in approved disposal containers.
Water spills are of particular concern due to the acute toxicity of cresylic acids to marine life. Clean up efforts should focus on containing the spill and quickly removing the cresylic acids that settle in deeper areas of the waterway. This can be aided greatly if the flow of water can be slowed or stopped. Further efforts should focus on removing as much of the dissolved cresylic acids as possible from the water using activated charcoal.
The composition and extent of any spill should be evaluated against local guidelines (ex. SARA Title III and RCRA in the U.S.) and reported to the proper agencies, if necessary. Any non disposable clean-up equipment should be thoroughly decontaminated with soap and water after use.
Source : SASOL / USA
Some significant points to note about Cresylic Acid
Below is a photo taken 10 years ago in the Irish Army Air Corps NDT shop, part of the Avionics / ERF building complex. Ardrox 666 can be seen spilled on the ground where it was free to leach through a shore onto the grass verge outside.
- 25% of fresh Ardrox 666 used by the Air Corps was Cresylic Acid. This percentage was higher in waste Ardrox 666 as Dichloromethane evaporated.
- That greenish / yellow stain dripping from the extractor fan is also Ardrox 666 from the air.