Nickel

(endorsed 1996)

Guideline

Based on health considerations, the concentration of nickel in drinking water should not exceed 0.02 mg/L.

General description

Drinking water generally contains very low concentrations of nickel. Concentrations reported overseas are usually less than 0.01 mg/L. Higher concentrations, up to 0.5 mg/L, have been reported where water has been in prolonged contact with nickel-plated tap and plumbing fittings; however, these higher concentrations are unusual.

Nickel is used in the electroplating industry and in alloys used in the chemical, marine, nuclear and aerospace industries. It is used as a catalyst in industrial processes, and in oil refining. Main releases to the environment are from the burning of fossil fuels and in waste discharges from electroplating industries.

Nickel is present in many foods. Highest concentrations occur in cocoa, soy beans and some cereals. It has been estimated that the average daily dietary intake is between 0.1 mg/day and 0.3 mg/day.

Typical values in Australian drinking water

In major Australian reticulated supplies, concentrations of nickel range up to 0.03 mg/L, with typical concentrations less than 0.01 mg/L.

Treatment of drinking water

Nickel can be co-precipitated with iron and manganese oxides.

Measurement

The nickel concentration in drinking water can be determined using inductively coupled plasma emission spectroscopy or graphite furnace atomic absorption spectroscopy (APHA Method 3500-Ni Parts B and C 1992). The limits of determination are approximately 0.02 mg/L and 0.005 mg/L respectively. Lower concentrations can be determined with pre-concentration using chelation or solvent extraction techniques.

Health considerations

Intestinal absorption of soluble nickel in drinking water can be as high as 27%, compared with only 0.7% from food. After absorption, nickel appears to be distributed to most organs, with higher amounts in the kidneys, lung and liver. It can cross the human placenta.

An extensive review and summary of the human and animal toxicity data for nickel is available (IPCS 1991).

In humans, long-term exposure may result in toxic effects to the kidney. Increased beta-microglobulin concentrations were reported among electroplating workers exposed to high amounts of nickel.

Nickel is known to be a common skin allergen and can cause dermatitis, particularly in younger women. While skin is sensitised, oral intake of low doses (0.0083 mg/kg body weight per day) may provoke contact dermatitis in sensitised individuals.

Several epidemiological studies have demonstrated that inhalation of nickel can cause lung, sinus and nasal cancer. There is no evidence that other organs are affected, or that nickel is carcinogenic when ingested.

Animal studies have reported altered body weights, some evidence of liver toxicity and mild kidney toxicity with high nickel doses (over 100 mg/kg body weight per day). Nickel has also affected the immune system in laboratory mice.

Some nickel compounds are carcinogenic when injected into laboratory animals but not when administered orally. Tests for mutagenicity with strains of bacteria have mostly been negative but gene mutations and chromosome aberrations have been reported in mammalian cells.

The International Agency for Research on Cancer has concluded that nickel compounds are carcinogenic to humans (Group 1, sufficient evidence of carcinogenicity in humans) (IARC 1990).

Derivation of guideline

The guideline value for nickel in drinking water was derived as follows:

$$\text{ 0.02 mg/L } = \dfrac{\text{ 5 mg/kg body weight per day x 70 kg x 0.1 }}{\text{ 2 L/day x 1000 }}$$

where:

• 5 mg per kg body weight per day is the no-effect level for altered organ-to-body-weight ratios in a 2-year study with rats (Ambrose 1976).

• 70 kg is the average weight of an adult.

• 0.1 is the proportion of total daily intake attributable to the consumption of water.

• 2 L/day is the average amount of water consumed by an adult.

• 1000 is the safety factor in applying the results of animal studies to humans (10 for interspecies variations, 10 for intraspecies variations and 10 to compensate for the lack of adequate studies on chronic effects and for increased intestinal absorption when taken on an empty stomach). An additional factor for carcinogenicity was not included as effects only occurred on inhalation (no effects were observed on ingestion) and were localised to the lung and nasal passages.

References

Ambrose AM, Larson PS, Borzelleca JG, Hannigar GR Jr (1976). Long term toxicologic assessment of nickel in rats and dogs. Journal of Food Science and Technology, 13:181–187.

APHA Method 3500-Ni Part B (1992). Nickel: Atomic Absorption Spectrometric method. Standard Methods for the Examination of Water and Wastewater, 18th edition. American Public Health Association, Washington.

APHA Method 3500-Ni Part C (1992). Nickel: Inductively Coupled Plasma method. Standard Methods for the Examination of Water and Wastewater, 18th edition. American Public Health Association, Washington.

IARC (International Agency for Research on Cancer) (1990). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans: chromium, nickel and welding. World Health Organization, IARC, 49.

IPCS (International Programme on Chemical Safety) (1991). Nickel. Environmental Health Criteria, 108. World Health Organization, IPCS.