Petrochemical Compounds: An Introduction

A petrochemical compound is an organic (based on carbon) compound derived from crude oil (petroleum) or natural gas, which were formed millions of years ago in the earth’s crust from decayed plants and animals.

These two primary classes of petrochemical are olefins (e.g. ethylene, butylene and propylene) and aromatics (e.g. benzene, toluene and xylenes) produced by chemical cracking (breaking large hydrocarbon molecules into simpler molecules, aided by a catalyst and high temperatures) and catalytic reforming (used to convert low-octane naphthas into high-octane gasoline blending components and often benzene, toluene and xylene aromatics for petrochemical uses.) Short-chain olefins, such as ethylene, are cracked from naptha or natural gas. Numerous derivates are manufactured from these petrochemical building blocks.  Olefins (also known as alkenes) are used in the production of various products including cosmetics.

Petrochemicals are made up of hydrocarbons (organic compound containing only carbon and hydrogen) and used in the automotive and aviation industries, in explosives, plastics, soaps and detergents, cosmetics, dyes, food packaging, pharmaceutical preparations, home furnishings, carpet backing, refrigerators, moulded products, technology – such as microchips in computers and CDs, synthetic fibres for clothes and furniture (such as nylon), rubbers, paints, bath and shower doors, ink, paint thinner, toys, diaper covers, textiles, antifreeze, floor polish, pens and pencils, lighters, dinnerware, insulation materials, chemical intermediates; to treat non-stick frying pans and for many more applications.

Petrochemical compounds either directly used in cosmetics or used in the production of cosmetic ingredients and their associated potential or known adverse health effects include, amongst others:

Benzoic acid – Produced by partial oxidation of toluene with oxygen, aided by a catalyst such as cobalt or manganese naphthenates for industrial uses. It is used to produce other chemicals such as benzoyl peroxide and phenol and can be found naturally in many foods. It is used as a perfume and pH adjuster in cosmetics and can cause allergic reactions and aggravate asthma in some individuals. It has also caused DNA damage in some animal studies.

Butylene glycol – Derived from butane and used as a humectant, solvent and skin conditioning agent in cosmetics. Can cause contact dermatitis and irritate the respiratory tract if inhaled.

Ethanol – Produced from ethene or the fermentation of sugar, starch or cellulose. It is used as a preservative and solvent in cosmetics. Ethanol can cause skin and eye irritation. Ingestion can cause nausea, vomiting and inebriation. Chronic ingestion can potentially cause liver damage. In animal studies reactions to ethanol have included reproductive effects, mutation, endocrine disruption and skin irritation. It is a penetration enhancer.

Ethanolamines (monoethanolamine) – Ethanolamine is an amino alcohol produced by reacting ethylene oxide with ammonia and is used in the production of surfactants and hair waving agents. It is also used as an ingredient in cosmetic products. It is a skin, eye and respiratory irritant and can cause allergic contact dermatitis. Ethanolamines are corrosive and rats repeatedly to ethanolamine via inhalation suffered from lesions to the lung, liver, kidneys, spleen and testes. It has also caused reproductive toxicity in animal studies. Ethanolamines may be contaminated with the carcinogen N-nitrosodiethanolamine (NDELA) in the presence of nitrosating agents. Long term application of ethanolamines to animals caused hepatic and liver damage. Other ethanolamines include diethanolamine (DEA) and triethanolamine (TEA).

Ethylene (Ethene) – A colourless gas produced in the petrochemical industry by steam cracking (at a very high temperature of around 850^oC) of hydrocarbons that is used to make polyethylene, ethyl benzene, ethylene oxide and other chemicals. These are then used to produce a range of products including plastic wrapping and cosmetics. Ethylene is an olefin and used in the production of polyethylenes. Its derivatives include ethylene oxide (used in the production of surfactants) and styrene monomer. Mild exposure to ethylene can cause euphoria , whilst higher concentrations can cause fatigure, dizziness, numbness, memory loss, hyperventilation and other symptoms.

Ethylene glycol – Toxic substance produced using a cataylsed condensation reaction between ethylene oxide and water and widely used as automotive anti-freeze, a solvent in the paint and plastic industries, for de-icing aeroplanes and it is also used in hydraulic brake fluids, wood stains, adhesives, tobacco and cosmetics as a fragrance, humectant, solvent and viscosity decreasing agent. Most of it is used in the production of polyethylene terephthalate (PET) resins used for cosmetic and other packaging. It can cause eye nose and throat irritation and is a reproductive and developmental toxicant. Ethylene glycol poisoning produces Central Nervous System effects such as coma, nausea and vomiting; and progressive kidney damage. Ingestion of ethylene glycol increases the amount of acid in the body causing metabolic problems. It is readily absorbed through the skin. Prolonged skin contact can cause irritation. Products containing ethylene glycol may be contaminted with suspected reproductive toxicants, ethoxyethanol and methoxyethanol.

Ethylene oxide – Non-ionic surfactants used in detergents and ethanolamines used in soaps and detergents are produced from ethylene oxide. It is likely to be a human skin, immune system, cardiovascular, reproductive, nervous system and respiratory toxicant. It is also a skin irritant, known human carcinogen and possible neurotoxicant that is banned from cosmetic products in the EU.

Glycol ethers – A large group of chemicals often used in industrial solvents and as ingredients in paints, varnishes, jet fuel de-icing additives, hydraulic fluids, as well as perfumes and cosmetics. The starting materials used for glycol ethers are ethane oxide and proprane oxide and the appropriate alcohols. Glycol ethers can be absorbed from skin contact with the liquid or through inhalation of the vapour. Most glycol ethers are readily absorbed through the skin and can dissolve the skin’s protective oils. Some of them can evaporate rapidly reaching hazardous levels in the air. Overexposure to glycol ethers can cause anaemia (a reduced number of red blood cells), intoxication, nausea and irritation of the skin, respiratory tract and eyes. Short term exposure can cause fluid accumulation in the lungs and severe liver and kidney damage. Glycol ethers have been shown to induce spontaneous abortion and possibly affect exposed female worker’s ability to deliver a live birth. Most glycol ethers can damage red blood cells or the bone marrow.

Isopropyl alcohol – An isomer of propanol produced by combining water and propylene used as an antibacterial, denaturant, fragrance ingredient and solvent used for oils, resins, cosmetics, hair colourants and household products. It is also used as a petrol additive. Isopropyl alcohol can irritate the eyes and mucous membranes. Repeated use can dry out the skin and cause flaking. Prolonged skin contact can cause corrosion. Ingestion of isopropyl alcohol can cause abdominal pain, shortness of breath, vomiting, nausea, hallucinations, unconsciousness and death. Acute inhalation can cause coughing, dizziness, headache and sore throat, along with the above symptoms. It is also a central nervous system depressant.

Mineral Oil (Paraffinum Liquidum) – Mixture of hydrocarbons obtained from petroleum that is used in cosmetic products as an emollient and film-former. Untreated and mildly treated mineral oils are known carcinogens according to the U.S. National Toxicology Program (NTP). It is said to cause photosensitivity, increasing the risk of skin damage upon exposure to the sun. Mineral oil is also said to trap dirt and toxins under the skin, which can promote acne. Mineral oil derivatives can be contaminated with carcinogenic polycyclic aromatic hydrocarbons (PAHS).

Parabens (Hydroxybenzoates) – Produced by esterification of the acid part of 4-hydroxybenzoic acid with the appropriate alcohol. They are used a preservatives in cosmetics. A number of studies have found parabens (commonly used in cosmetic products and deodorants as preservatives) to be oestrogenic (mimic oestrogen in the body) and certain parabens have been detected in the breast tissue of women diagnosed with breast cancer. Reportedly, the main influence in the onset of breast cancer is exposure to oestrogen over a lifetime. Some chemicals in the environment can be stored in the breast tissues and present oestrogenic effects, which is worrying because women frequently apply underarm deodorants containing parabens on shaved skin (which aids absorption of these compounds). Parabens have also been found in human blood and urine. Parabens may also cause contact dermatitis and skin sensitisation in some individuals.

Paraffin Wax – A solid mixture of hydrocarbons obtained from petroleum. Paraffin wax is often used as a moisturiser in cosmetics and as a food additive. It has caused skin irritation in animal studies and tumours (see also petrolatum.)

Petrolatum – Petrolatum, most commonly known as petroleum jelly is a translucent jellylike mixture of semi-solid hydrocarbons derived from petroleum. It is used in cosmetic products such as moisturising creams, wax depilatories, make-up and baby creams, as an emollient. It may be contaminated with carcinogenic polycyclic aromatic hydrocarbons (PAHs).

Petroleum Distillates – Petroleum distillates are a group of hydrocarbon-based chemicals extracted by distillation during the refining of crude oil and used in a range of products and applications as solvents. Examples include gasoline, naptha, mineral spirits, kerosene, paraffin wax and tar. They are used as the main ingredient in consumer products such as, furniture polishes, adhesives, paint solvents, motor oil and cosmetic products. Cosmetic grade petroleum distillate mainly consists of C10-C16 paraffinic, naphthenic, and isoparaffinic hydrocarbons. Many consumer products contain hydrocarbons that are not petroleum distillates, but still cause toxic effects, such as benzene, toluene, xylene, pine oil, turpentine and limonene. Petroleum distillates are suspected cardivascular and blood toxicants, neurotoxicants and respiratory toxicants. Inhaling small amounts of petroleum distillates and other hydrocarbons can cause chemical pneumonia, pulmonary damage and even death. They can also cause skin irritation and sensitivity to light. Petroleum distillates can cause anaesthesia and dermatitis. Many petroleum based products have been linked to cancer and petroleum distillates can be contaminated with butadiene, a known carcinogen. In the EU a number of petroleum distillates are banned for use in cosmetic products, with others being permitted provided certain impurity limits are not exceeded. In some cases particular distillates are permitted if it can be shown that the substances from which it they were produced are not carcinogens.

Phthalates – Phthalates, used as plasticisers and fixatives in cosmetic products and ubiquitous in consumer products, have been lambasted by some quarters for their potential endocrine disrupting properties in animal studies. Research has shown that they have an additive effect and can block the male hormone testosterone. A Harvard study found that men had greater phthalate levels in their urine within 48 hours of applying cologne or aftershave, suggesting that these sorts of personal care products are a source of exposure. They have also been found to cause abnormal reproductive hormone levels in 3-month old infants who were exposed via their mothers breast milk, and have been linked in some studies with male reproductive disorders such as cryptorchidism (undescended testes), hypospadias (where the urethra is abnormally positioned on the underside of the penis, testicular atrophy (shrinking of the testes), lows sperm counts and testicular cancer. Three have been banned in the UK but diethyl phthalate is still widely used in a range of cosmetic products. Certain phthalates such as dibutyl phthalate (banned in EU cosmetic products, but not in the U.S.) can block male hormones, known as androgens, leading to feminisation of male offspring in animal studies. They have also been linked to reproductive abnormalities in human epidemiological studies. When used as fragrance carriers there is no legal requirement to feature phthalates on cosmetic ingredients labels and there is still a risk of contamination. Phthalates are classified as hazardous waste.

Phenol – A carbolic acid that used to be obtained from coal tar but is now manufactured from petroleum. It is is used in phenol-formaldehyde resins, as a antiseptic in lipsticks, lipbalms, shaving creams and hand lotions; and is the starting material for chemicals such as alkylphenol, phenoxy acids, salicylic acid and phenolphthalein. Phenol is a toxic agent that can adversely affect the central nervous system (CNS). It was used by the Nazis as a means of rapid individual execution during the Second World War. It is neurotoxic and nephrotoxic (toxic to the kidneys), poisonous by ingestion, toxic by skin contact and a severe skin and eye irritant. Because phenol damages the skin, it can increase the penetration of other toxic substances. Phenol may be a skin tumour promoter in certain strains of mice.

Polyethylene (polyethene) – A themoplastic produced by cracking petroleum distillates into small ethylene molecules that can be re-arranged. Poly basically means many ethylene (ethene) groups. It is used in cosmetics as an abrasive, bulking agent, viscosity increasing agent, oral care agent, emulsion stabiliser and film former. There is limited evidence of polyethylene having a carcinogenic effect in animal studies, causing liver and kidney damage and brain and nervous system effects, and some evidence of immune system toxicity. It may be a human immune system toxicant. Ethylene can contain impurities such as propylene, carbon dioxide, carbon monoxide, sulphur, hydrogen and acetylene, although these are said by the Cosmetic Ingredient Review to be of a concentration too low to warrant concerns about potential toxicity.

Polyethylene glycol (PEG) - Polyethylene glycols (PEGs) are a group of polymers of ethylene oxide. They are used in cosmetics as surfactants, solvents, cleansing agents, skin conditioning agents and humectants. PEG compounds can become contaminated with the probable carcinogen 1,4-dioxane, along with other toxic impurities such as ethylene oxide, polycyclic aromatic hydrocarbons (PAHs) and heavy metals, including lead, iron, cobalt, nickel, cadmium and arsenic. They are readily absorbed through damaged skin.

Propylene – Found in coal gas and can be produced by cracking petroleum. Large quantities of propylene are used in the manufacture of resins, fibres and plastics. It can be produced as a byproduct of ethylene production using steam cracking or as a by-product of refinery operations. Inhalation can cause anaesthetic effects at high concentrations.

Propylene glycols – The collective name for monopropylene glycol (MPG), dipropylene glycol (DPG) and tripropylene glycol (TPG), derivates of propylene oxide. Propylene glycol (monopropylene glycol) is produced by non-catalytic hydrolysis of propylene oxide using high temperatures and pressures and is used in anti-freeze and de-icing solutions for cars, boats and aircraft as well as being commonly used in food and cosmetics. In cosmetics it is widely used as a humectant, fragrance ingredient, viscosity decreasing agent, solvent and wetting agent. It can cause skin irritation, eye irritation and contact allergies. Propylene glycol is a penetration enhancer and weak skin sensitiser in humans. If ingested it may cause irritation of the gastrointestinal tract. It may be absorbed through the skin and cause similar effects to exposure by ingestion. Propylene glycol can defat the skin, removing its natural protective sebum. There is some evidence suggesting that it may be toxic to the central nervous system (CNS) and a respiratory toxicant. High oral doses in children have caused CNS depression and high doses administered to animals have caused brain, nervous system and reproductive effects. It may be mutagenic in humans and cause reproductive effects and birth defects based on animal test data.

Surfactants – Until the 1940s soap was used for personal and laundry washing, but a shortage in oils and fats during World War II resulted in the development of various synthetic detergents and in the 1950s petroleum based alkylbenzenesulphonate (ABS) began to serve as a large-scale replacement. Petrochemical surfactants are produced from small building blocks such as ethylene, n-paraffins and benzene obtained from crude oil. The main products are then converted to a variety of intermediates such as alpha-olefins, oxo-alcohols, primary alcohols, ethylene oxide and alkyl benzene, which undergo further transformation to produced the appropriate surfactants. Petrochemical surfactants include linear alkyl benzene (LAS), linear alkylbenzene sulphonate (LABS), alcohol sulphate (AS), alcohol ether sulphate (AES), alcohol ethoxylate (AE), alkyl phenol ethoxylates (APE), alkyl ammonium quaternary compounds and fatty acid alkanolamides/mines (which are commercially prepared from alkanolamines, particularly diethanolamine via reaction with a fatty acid at high temperatures and can be contaminated with carcinogenic nitrosamines.) Some surfactants are toxic and have given rise to health and environmental concerns, due to their presence in wastewaters and in some cases poor diodegradibility and toxicity to aquatic organisms. For example, alkyl phenol ethoxylates (APEs) have been found to be oestrogenic, mimicking the sex hormong oestradiol in cultured cells and living organisms, even at low levels. During the washing process detergent constitutents are released into wastewaters. Sewage treatment problems were noticed in the UK and Germany as far back as the 1950s when increased surfactant concentrations were found in sewage waters, rivers and groundwater supplies receing effluents from cesspools or septic tanks. It was later discovered that the surfactant dodecylbenzene sulphonate did not readily biodegrade and excess foam in rivers and sewage waters was in turn, the result of propylene-based alkylbenzenesulphonates (ABS) not being adequately biodegraded by the natural bacteria in effluents. Consequently ABS was replaced with linear alkene benzene sulphonate (LAS). Crude oil and natural gas supplies are also limited which has turned people’s attention to renewable resources.

Solvents (such as acetone, benzene, ethanol, isopropyl alcohol, toluene, xylenes) – Used in numerous cosmetic products (benzene is banned from cosmetic products in the EU) many of them are neurotoxic and associated with numerous other adverse effects depending on the substance, including skin, eye and respiratory tract irritation, defatting of the skin, CNS depression, respiratory irritation, asthma, kidney damage, cancer, reproductive damage and more.