Aluminium

2021-02-26

Aluminium (or aluminum) is a chemical element in the boron group with symbol Al and atomic number 13. It is silvery white, and it is not soluble in water under normal circumstances. Aluminium is the third most abundant element (after oxygen and silicon), and the most abundant metal, in the Earth’s crust. It makes up about 8% by weight of the Earth’s solid surface. Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is found combined in over 270 different minerals. The chief ore of aluminium is bauxite. Aluminium is remarkable for the metal’s low density and for its ability to resist corrosion due to the phenomenon of passivation. [1]

Uses [2]

Aluminium is used in many industries to make millions of different products and is very important to the world economy. Structural components made from aluminium are vital to the aerospace industry and very important in other areas of transportation and building in which lightweight, durability, and strength are required. The use of aluminium exceeds that of any other metal except iron. Pure aluminium easily forms alloys with many elements such as copper, zinc, magnesium, manganese and silicon. All modern mirrors are made using a thin reflective coating of aluminium on the back surface of a sheet of float glass. In addition, telescope mirrors are coated with a thin layer of aluminium. Other applications are electrical transmission lines, and packaging (cans, foil, etc.). Because of its high conductivity and relatively low price compared to copper, aluminium was introduced for household electrical wiring to a large degree in the United States in the 1960s. Unfortunately problems on the functioning were caused by its greater coefficient of thermal expansion and its tendency to creep under steady sustained pressure, both eventually causing loosening the connection; galvanic corrosion increasing the electrical resistance. The most recent development in aluminium technology is the production of aluminium foam by adding to the molten metal a compound (a metal hybrid), which releases hydrogen gas. The molten aluminium has to he thickened before this is done and this is achieved by adding aluminium oxide or silicon carbide fibres. The result is a solid foam that is used in traffic tunnels and in space shuttle.

In the Environment [3]

Aluminium cannot be destroyed in the environment; it can only change its form. In the air, it binds to small particles, which can stay suspended for many days. Under most conditions, a small amount of aluminium will dissolve in lakes, streams, and rivers. Some plants can take it up from soil. Aluminium is not accumulated to a significant extent in most plants or animals.

Sources of Emission & Routes of Exposure

Sources of Emission [3,4]

General Populations

  • Virtually all food, water, air, and soil contain some aluminium.
  • The average adult in the United States eats about 7-9 mg aluminium per day in their food.
  • Living in areas where the air is dusty, where aluminium is mined or processed into aluminium metal, near certain hazardous waste sites, or where aluminium is naturally high.
  • Eating substances containing high levels of aluminium (such as antacids) especially when eating or drinking citrus products at the same time.
  • Children and adults may be exposed to small amounts of aluminium from vaccinations.
  • Very little enters your body from aluminium cooking utensils
  • The intake of aluminium from food and water is low, especially compared with that consumed by people taking aluminium-containing medicinals.
  • Inhalation exposure and dermal contact may also contribute a small amount to an individual’s daily aluminium exposure.

Routes of Exposure [4]

Inhalation – generally limited to occupational exposure.

Oral – primary route of exposure for the general population. Aluminium is found in food, drinking water, and medicinal products such as antacids and buffered aspirin.

Dermal (skin) contact – minor route of exposure; aluminium is found in some topically applied consumer products such as antiperspirants, first aid antibiotics, and sunscreen and suntan products.

Health Effects [3,4]

Exposure to aluminium is usually not harmful, but exposure to high levels can affect your health. The most sensitive target of aluminium toxicity is the nervous system.

Impaired performance on neurobehavioral tests of motor function, sensory function, and cognitive function have been observed in animals. Neurobehavioral alterations have been observed following exposure of adult or weanling animals and in animals exposed during gestation and/or lactation.

Workers who breathe large amounts of aluminium dusts can have lung problems, such as coughing or abnormal chest X-rays. Some workers who breathe aluminium dusts or aluminium fumes have decreased performance in some tests that measure functions of the nervous system. Some people with kidney disease store a lot of aluminium in their bodies and sometimes develop bone or brain diseases, which may be caused by the excess aluminium. Some studies show that people exposed to high levels of aluminium may develop Alzheimer’s disease, but other studies have not found this to be true. It is unclear whether aluminium causes Alzheimer’s disease.

There is some indication that skeletal effects (e.g., osteomalacia) can result from long-term use in some individuals. Studies in animals show that the nervous system is a sensitive target of aluminium toxicity. Obvious signs of damage were not seen in animals after high oral doses of aluminium. However, the animals did not perform as well in tests that measured the strength of their grip or how much they moved around. It is unknown whether aluminium affects reproduction in people. Aluminium does not appear to affect fertility in animals.

Safety

First Aid Measures

Eye Contact:

  • Check for and remove any contact lenses. In case of contact, immediately flush eyes with plenty of water for at least 15 minutes. Get medical attention if irritation occurs.

Skin Contact:

  • Wash with soap and water. Cover the irritated skin with an emollient. Get medical attention if irritation develops.

Inhalation:

  • If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention immediately.

Ingestion:

  • Do NOT induce vomiting unless directed to do so by medical personnel. Never give anything by mouth to an unconscious person. If large quantities of this material are swallowed, call a physician immediately. Loosen tight clothing such as a collar, tie, belt or waistband.

Exposure Controls & Personal Protection

Engineering Controls

Use process enclosures, local exhaust ventilation, or other engineering controls to keep airborne levels below recommended exposure limits. If user operations generate dust, fume or mist, use ventilation to keep exposure to airborne contaminants below the exposure limit.

Personal Protection

the following personal protective equipment is recommended when handling aluminium:

  • Safety glasses
  • Lab coat
  • Gloves

Personal Protection in Case of a Large Spill:

  • Safety glasses
  • Lab coat
  • Gloves

Regulation [6,7]

United States

OSHA: The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for aluminium is 15 milligrams per cubic metre (mg/m3) of air for total dust, and 5 mg/m3 for the respirable fraction, as an 8-hour time-weighted average (TWA) concentration [29 CFR 1910.1000, Table Z-1].

NIOSH: The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for aluminium of 10 mg/m3 for total dust, and 5 mg/m3 for the respirable fraction, as a TWA for up to a 10-hour workday and a 40-hour workweek [NIOSH 1992].

ACGIH: The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned aluminium a threshold limit value (TLV) of 10 mg/m3 for metal dust, as a TWA for a normal 8-hour workday and a 40-hour workweek [ACGIH 1994, p. 12].

Australia

Safe Work Australia: Safe Work Australia has established a 8 hours time weighted average concentration for aluminium (metal dust)of 10 mg/m3 and aluminium (welding fumes) of 5 mg/m3.

References

http://en.wikipedia.org/wiki/Aluminium

http://www.lenntech.com/periodic/elements/al.htm

http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=190&tid=34

http://www.atsdr.cdc.gov/toxguides/toxguide-22.pdf

http://www.sciencelab.com/msds.php?msdsId=9922844

http://www.osha.gov/SLTC/healthguidelines/aluminum/recognition.html

http://www.safeworkaustralia.gov.au/sites/swa/search/results?k=aluminium+exposure+limits