There is a wide range of opinions on the environmental impact of different foam concentrates. Among this information is considerable misinformation. This technical note is aimed at providing an overview to this issue.

From the environmental standpoint any man made substance that is discharged into the environment is undesirable, particularly if it is not a naturally occurring substance. It is important for us to avoid unnecessary discharge of any chemicals whether they are pollutants or not.

There are seven main environmental problems that may potentially be associated with fire fighting foams.

• Biodegradability
• Fish toxicity
• Phosphates
• Nitrogen
• Heavy metals
• Ethylene glycol based solvents
• Fluorochemicals

Most people are aware that using biodegradable shampoos and washing detergents is good for the environment. We should also use biodegradable fire fighting foams as well. If the chemicals we discharge into the environment are biodegradable then they will be removed from the environment reasonably rapidly by the actions of microbes. Since biodegradability is a well-known issue most if not all fire fighting foams will be biodegradable. Unfortunately being biodegradable is not enough.

There is also a negative environmental aspect to biodegradability. When chemicals biodegrade the breakdown process requires oxygen. There are two measures for this, the Biological Oxygen Demand or BOD (demand by the microbes) and the Chemical Oxygen Demand or COD (oxygen used in chemical decomposition). The oxygen demand during the breakdown of chemicals discharged into bodies of water can have very serious short term impact on aquatic life by removing oxygen from the water to the point where aquatic life dies from lack of oxygen. Consequently, we need to avoid discharging fire fighting foams into small lakes and streams.

Foam concentrates (synthetics and protein based) made by all reputable manufacturers would be classified as readily biodegradable. Due to their higher solids content protein based foam will have a larger overall impact on aquatic oxygen levels when they biodegrade.

When fire fighting foams are used there is a risk that the run off will find its way into streams, rivers and the ocean. Fish are relatively sensitive to the presence of pollutants in the water.

Many years ago when we first tested our fire fighting foams for fish toxicity we found that oxygen reduction in the water killed all the fish within 24 hours. To keep the fish alive so that we could conduct the toxicity test we needed to continuously add oxygen to the water while the fish toxicity testing is conducted. Quite clearly, oxygen depletion during biodegradation is a more immediate threat to aquatic fauna than the toxicity of synthetic detergents.

Under these circumstances fish toxicity is not a major environmental problem for AFFF type products.

Some raw materials used in fire fighting foams could contain phosphates. Phosphates act as fertilisers and will promote excessive growth of some plants and algae. When phosphates are discharged into waterways the ecology can be damaged by excessive plant growth along the banks that blocks the waterways or by algae growth.

We have never used materials containing phosphates in the manufacture of our foam concentrates and it is unlikely that any major manufacturer would.

Nitrogen in organic form is also a fertiliser and produces similar problems to phosphates, though higher concentrations are required.

Many surfactants used in the manufacture of synthetic foams have small levels of nitrogen. The level of nitrogen is relatively low and very little environmental impact can be expected from the nitrogen levels found in synthetic foams.

Protein based foams (protein, fluoroprotein and FFFP foams) contain substantially more organic nitrogen than synthetic foams (more than 10 times the amount). These foams act as very effective fertilisers and will promote excessive growth of plants and algae in waterways.

Heavy metal ions accumulate in living tissue and can be quite damaging to living organisms. Lead poisoning in humans is a typical example. Releasing heavy metals into the environment should be avoided.

Protein based foams may contain heavy metals (zinc), generally synthetic foams do not.

The concept of earth friendly foams was based on the elimination of ethylene glycol based solvent in the manufacture of synthetic foams. Ethylene glycol based solvents such as the diethylene glycol ether (butyl di-icinol) commonly used in AFFF's are considerably more toxic than propylene glycol based solvents. The US EPA introduced requirements for any significant release of these solvents to be a reportable event.

Concern over these solvents differs from country to country.

All solvents should be treated carefully. Specifications that require high refractive index readings for foam concentrates force manufacturers to add more solvent than is required for fire fighting performance. This adds to the environmental impact of the foam concentrate without any fire fighting benefit. The justification for specification requirement is to allow the use of refractometers to measure the proportioning rate of foam in systems and on fire apparatus. Today, conductivity meters are low cost and more accurate than refractometers, so that the use of refractometers should be discontinued on environmental grounds. There is also an economic benefit for this change.

While the fluorosurfactants used in the manufacture of AFFF's, fluoroprotein foams and FFFP's are biodegradable part of the surfactant is not broken down and remains in the environment. The recent announcement by 3M regarding the build up of these chemicals in humans has highlighted this issue.

The major contributor to the build-up of fluorochemicals is not fire fighting foams but ScotchGard™ chemicals used for fabric protection. Fire fighting foams are most likely to be considered an essential use for fluorochemicals.

Fluorosurfactants are essential to the performance of AFFF, fluoroprotein and FFFP foams. However, there are things we can do to minimise the impact of these chemicals.

Orion Safety has been researching methods of reducing the use of fluorosurfactants for many years and we have patented methods of doing this. When we compare our AFFF products with 3M AFFFs our products use approximately 75% less fluorosurfactant for similar fire fighting performance. Using less fluorosurfactant greatly lowers the environmental impact from our products.

We live in a world that is becoming more aware of the impact we are having on the environment and the fire fighting industry must keep up with this trend.

The use of fire fighting foams could become a major environmental issue unless we develop technologies that minimise their environmental impact. We must also minimise their discharge into the environment, particularly waterways and sewers. The use of lower impact training foam can also reduce the discharge of fluorochemicals from training.

The selection of foam concentrates with lowest environmental impact is a complex process that is made more difficult by lack of complete information. There is currently no definitively superior product. Claims that protein based foams have lower impact than synthetic foams cannot be substantiated. These two types of foams will have different impacts on the environment, but neither is particularly superior in this regard.