Backgrounder: Chloramines

What are Chloramines?

Chloramines are a group of chemical substances formed when chlorine and ammonia are combined in water. Inorganic chloramines, free chlorine and organic chloramines are chemically related and are easily converted into each other; thus, they are not found in isolation.

Although they have been found to be toxic to the environment, chloramines continue to make an important contribution to the protection of human health in Canada through the disinfection of drinking water supplies. While chloramines are toxic to fish, Health Canada research has determined that chloramines used as a disinfectant for drinking water do not pose a health threat.

What are common uses of these substances?

Chloramines are frequently used as a disinfectant for drinking water, wastewater, effluents and in cooling waters. They are released to the environment by a variety of municipal and industrial sources. They are found in drinking water, sewers, effluents from sewage treatment plants and discharges from industrial and cooling water processes treated with chlorine or chloramines.

Other sources of releases of chloramines include breaks and leaks in water mains, fire fighting runoff and storm-water runoff from domestic water supplies treated with these substances.

Why have Chloramines been found to be toxic to the environment?

Chloramines can remain chemically stable in water from hours to days. They are highly toxic to fish and other organisms which live in water. These substances are not found to be bioaccumulative, or to transfer up the food chain.

Risk assessments of chloramines were conducted on two wastewater discharges, and a cooling water discharge to rivers and a lake. The scientific assessment of chloramines found that they are entering the environment in quantities and concentrations and under conditions that are having, or that may have an immediate and long-term effect on the aquatic environment at various locations across Canada.

An assessment of drinking water releases found that even very small direct discharges of chloramine-treated potable water could result in impacts on aquatic species. Conclusions are supported by sampling which showed higher chloramine concentrations in surface waters receiving chloramine in effluents. Water main breaks which released chloraminated drinking water in the Lower Mainland of British Columbia have resulted in the deaths of many thousand salmonids and several thousand invertebrates. Concentrations of chloramines as low as 0.07 mg/L (70 µg/L) have been shown to be lethal to coho salmon in 96 hour studies.

Why were Chloramines only assessed for environmental toxicity and not human health?

Evaluation of information at the outset of the assessment indicated that action taken to reduce release on the basis of effects on more sensitive environmental organisms would be protective for human health. The focus of the assessment was effects on more sensitive environmental organisms, exposed directly to chloramines in the aquatic environment, as recommended by the Ministers' Expert Advisory Panel on the Second Priority Substances List.

In 1995, Health Canada's Drinking Water Quality Program evaluated potential health effects associated with exposure to chloramines and established a drinking water guideline for total chloramines. Though the primary focus of the Canadian Environmental Protection Act, 1999 (CEPA), assessment was on environmental organisms that are more sensitive to chloramines, Health Canada determined there was no significant new information that would materially alter the findings of the earlier drinking water assessment on these substances. Selection of appropriate control measures must ensure health protection, while minimizing the potential for harm to more sensitive environmental organisms.

What are the next steps for the federal government to reduce the effects of Chloramines in the environment?

The federal government will initiate a risk management process with stakeholders to limit chloramine exposure to fish and aquatic insects in surface waters from the largest sources (municipal wastewater facilities, municipal drinking water and industrial sources).

Under CEPA, the federal government has two years to develop preventive or control measures for chloramines, and a further 18 months to finalize them.

A range of options is available to reduce or minimize releases of substances that are found to be toxic. They include regulatory and voluntary initiatives, economic measures, environmental quality or release guidelines, codes of practice and pollution prevention plans.

For more information please contact: Danie Dubé Environment Canada (819) 953-0356

Michele Giddings Health Canada (613) 952-2594