Fluoride as a pollutant

Toothpaste contains sodium fluoride (NaFl).

Toothpaste contains sodium fluoride (NaF).

Image source

You probably know that fluoride is in your toothpaste and sometimes added to drinking water to minimize tooth decay. Recently, ABC Catalyst screened an interesting documentary article about “Water Fluoridation“.

  1. What is the recommended dosage for adding fluoride to water supplies?
  2. Why do dentists and health professionals recommend fluoridated water?
  3. What is the evidence that fluoride is beneficial when added to water supplies?
  4. Some people protest against governments adding fluoride to water supplies – what are their reasons?

Did you know fluoride is considered a pollutant in high doses? Fluoride compounds include a range of chemicals containing the element fluorine (F). The National Pollutant Inventory  lists the following information about this pollutant:

  • Physical and chemical properties
  • Sources (natural and anthropogenic)
  • Transport mechanisms (air and water currents, wet deposition)
  • Sinks (neutralized in water and soils)
  • Health effects
  • Environmental effects

More information:

Tasks for week starting Monday 27th August

Do you think the “Portland Aluminium Macropod Management Plan” has been effective in preventing fluoride exposure at the “Smelter in the Park”? Explain your evaluation, using evidence to support your decision.
1. Complete the sulfur dioxide experimental report and submit.
2. Complete the three column “Pollutant Comparison table” and submit (SO2,
mercury and fluoride)
3. Complete the SAC task sheet – written response to questions
about fluoride data at Portland Aluminium – an evaluation of management
strategies. This task should be done in two hours only and without any
additional resources. Please submit to me prior to next Monday 3rd
September evening.
4. Review this week’s slideshow and make sure you understand the answers
to each of the questions. (Check your emails)
5. Review the ” University of Arizona – Biology Toxicology Tutorial at
Great for revision of effects of pollution on human health, as well as
terms and definitions.
6. Print out the Study Notes and check of the Area of Study 1 concepts -
what do you need to do more work on?
Next Wednesday evening (7.30pm) we will start Area of Study 2:
Environmental Management Systems.
This week’s Blackboard Collaborate session: “Evaluation Of Pollution Management Strategies”

Strategies to reduce the effects of Fluoride pollution

Figure 1 (above) shows a cross-section of an aluminium smelting pot and the flow of fluoride through the system. The covered pots reduce the amount of particulates and gaseous emissions that escape into the pot rooms. The gases produced during electolysis are trapped and then piped to the A398 Recovery System (Figure 2, Below) , which consists of a bed of fluidized alumina, which traps the fluoride emissions as they are pumped through from underneath the conveyor. the fluoride-rich alumina is then conveyed to the smelting pots. Fluoride helps to lower the melting point of the alumina so that less energy is required to produce molten aluminium. Less fluoride inputs are required as the about 99.8% of the fluoride is recycled in this manner.

The pot rooms have laser-light monitors which have a green/amber/red indicator that shows the level of fluoride emissions inside the building. When the red light shows that is an indication that proper procedures have not been followed and excess fluoride has escaped from the pots. In this case, workers will evacuate the pot-room until the gases can be cleared. Pot room workers have regular urine and blood tests to determine their exposure to fluoride emissions and wear monitoring badges which also indicate exposure.

Fluoride as a Pollutant

Fluoride is added to our drinking water, so it can’t be a pollutant, right? In fact, compounds of fluoride have many uses:

  • Hydrogen fluoride is used to make aluminum, chloroflurocarbons (CFCs), aluminum fluoride, sodium fluoride and other fluoride salts.
  • Petroleum, chemical, and plastics industries.
  • Separation of uranium isotopes.
  • Cleaning metals, bricks, or remove sand from metal castings.
  • Etching glass and enamel, polishing glass and galvanizing iron.
  • Brewing
  • Clouding light bulbs

Fluorides are everywhere throughout the environment, but at very low levels that are not believed to be harmful. Fluoride compounds can be ingested or inhaled, usually in an industrial or manufacturing environment. Small amounts of sodium fluoride help prevent tooth decay, but high levels may harm your health. In children whose teeth are forming, excessive fluoride levels may cause dental fluorosis with visible changes in the teeth. In adults, high fluoride over a long time may lead to skeletal fluorosis with denser bones, joint pain, and limited joint movement. This is rare. High levels of fluorine or hydrogen fluoride gas can cause muscle spasms, harm the lungs and heart and cause death. At low levels they can irritate the eyes, skin and lungs. Contact with hydrofluoric acid (even diluted) can burn the eyes (causing blindness) and skin, causing severe burns deep beneath the skin damaging internal tissues. This can occur hours after contact, even if no pain is initially felt. Contact with hydrofluoric acid happens mainly in the workplace. Long-term exposures may damage the kidneys and liver.

Read about the sources of fluoride and environmental effects of fluoride at the National Pollutants Inventory site.

The Mystery of the Indian Village Water” – chronic human health effects of fluoride ingestion in drinking water

Fluorosis – more human health effects. Beware of some sources of information about fluoride as a pollutant – there are some misinformed alarmists who have not cited references nor checked the accuracy of their data.

Read about fluoride emissions at Portland Aluminium here: “Environmental Improvement Plan 2003-2004” and “Long-term management of fluoride emissions”.

 

Report on your findings from Portland Aluminium

Portland Aluminium2-small

Water discharge from Portland Aluminium

By now you should have all your information, including relevant data, about fluoride as a pollutant at Portland Aluminium. Your report should include the characteristics of fluoride, including strategies that reduce the risk of pollutants affecting human health and the environment as well as the direct and indirect effects on the health of humans and the environment.

“On completion of this unit the student should be able to describe the characteristics of pollutants and evaluate the management options for reducing the risk of a pollutant affecting the health of the environment and humans.”

It is important that you make an attempt to evaluate the management options that Portland Aluminium have implemented to reduce fluoride emissions at the smelter. Have they been successful? Could they  be improved? Compare emissions from Portland to other aluminium smelters – how do they measure up?

Portland Aluminium tour

Portland Aluminium2 small

The Portland Aluminium smelter is situated on 600 hectares of land, 500 of which form “Smelter in the Park”, a once-barren area that has been revegetated with a large variety of indigenous plants. This area forms a buffer zone, that protects surrounding residents from the full impact of gaseous emissions from the smelter. There are five monitoring stations at different locations around the smelter that provide data on fluoride and sulfur emissions on a regular basis. Portland Aluminium also routinely test their workers, using urine and blood tests, as well as exposure badges, which monitor the levels of fluoride that staff have been subjected to.

Environmental scientists also do water testing and take tail-bone samples of the local kangaroos and teeth, bone and horn samples of the beef cattle , to test for long-term fluoride exposure. An international botanist expert visits annually to check for signs that toxic emissions may be affecting local vegetation. Signs of fluoride exposure include yellowing and curling of leaves and tissue death.

Portland Aluminium use several methods to prevent excessive fluoride emissions, including the A398 fluoride recovery system, in which fluoride emissions are captured from the hooded aluminium pots and forced through a conveyor of alumina, to form reacted or fluoride-enriched alumina. This is then added to the pots, which reduces the temperature (and therefor the energy required) to obtain the pure aluminium. The particulate and gaseous emissions are filtered through huge canvas bags, also coated with alumina, which traps 98% of fluoride.

In the potrooms, the major point source of fluoride emissions, Portland Aluminium have laser air monitoring of gaseous fluoride, with a traffic light system – green, amber and red. Between 045ppb and 600ppb, the lights are green; between 600ppb and 800ppb the lights are amber and above 800ppb the lights are red, which indicates an error in the process – too many hoods open at the same time.

The Victorian governmetn has produced this site, “Fluoride in the air environment“, which describes the sources of fluoride in Victoria and how it is monitored, including EPA limits.

Week 1, Term 3 – Unit 4

Anti fluoride protest posters by Ben Kraal.

Photo Source - Most of the anti-fluoride protest is scare-mongering and irrational – note the swastika!

As I will be with the Year 9/10 camp, at Rubicon during the first week back at school, you will need to work through Chapters 1 and 2 in class. The Area of study is pollutants, with case studies of mercury, sulphur and fluoride. In the previous post there are some worksheets for you to download and complete.

You may have heard about fluoride in the news recently – there have been bomb threats to Barwon South West Water and a Victorian MP is under police guard after fluoride has been intoruduced to Geelong’s water supply. Warrnambool received fluoride in the water supply last year after many months of contentious debate. Some people claim it is poison, while many scientists and dentists believe it reduces the incidence of tooth decay. Should we consider it as a pollutant?

Unit 4: Pollution

Photo Source

Over the two week study break and before you return to school on Monday 13th July, you need to have read Chapters 1 and 2 from the “Issues of Sustainability” textbook. This is an introduction to human health and the environmental effects of pollution in the air, water and soil. Try this worksheet to match various terms with their definitions: environmental-pollutants-worksheet.

Use the following to write notes about mercury, sulphur dioxide and fluoride: unit-4-pollutants-table

Fluoride emissions at Portland Aluminium

 Photo Source

Following our excursion to Portland Aluminium on Wednesday 6th August you will be required to complete a report considering the fluoride emissions of aluminium production. Make sure your report includes the following information:

  • Have you identified where fluoride comes from and whether it is a point source or diffuse source?
  • Is it a solid, liquid or gas pollutant?
  • How is it transported through the environment?
  • Does it bio-accumulate?
  • What are the direct and indirect human health effects?
  • What are the direct and indirect environmental effects?
  • How have Portland Alcoa Aluminium reduced fluoride emissions and by what percentage?
  • How does Portland Alcoa Aluminium monitor emissions and who do they report to?
  • What requirements does this organisation impose upon PAA and what are the penalties for non-compliance?
  • Using your knowledge of the characteristics of pollutants suggest ways in which the PAA could improve their environmental management to reduce risks associated with pollutants.
  • Assess the credibility of primary data collected; compare data collected relating to the pollutant with relevant standards or protocols.