Heavy metal.
Nickel, a major environmental pollutant, is known for its clastogenic, toxic, and carcinogenic potential. The carcinogenic potential of nickel compounds depends largely on their solubility. The particulate nickel compounds like Ni3S2 or NiO are strong carcinogen, whereas the soluble nickel (II) salts exert weaker effects. (ref. ID; 6934)

[Ni]
Test organisms;
Oligochaeta: Limnodrilus hoffmeisteri (ref. ID; 4453)
Nematoda: Caenorhabditis elegans (ref. ID; 4474)

[Ni: an atomic absorption standard solution]
Test organisms;
Rotifera: Brachionus calyciflorus (ref. ID; 127)

[Ni2+]
Test organisms;
Protozoa: Euplotes mutabilis (ref. ID; 6934)

[Nickel(II) Chloride, Anhydrous] CAS[7718-54-9] UN3288
Trade name; nickel chloride
Chemical formula; NiCl2
Chemical characteristics; water soluble
Purpose for use; fungicide
Test organisms;
Green algae (formerly including protozoa): Chlamydomonas reinhardtii (ref. ID; 3904)
Protozoa: Euglena gracilis (ref. ID; 3312)
Oligochaeta: Dendrobaena octaedra (ref. ID; 6928)
Oligochaeta: Eisenia fetida (ref. ID; 4631, 6895, 6982)
Oligochaeta: Enchytraeus albidus (ref. ID; 6982)
Nematoda: Caenorhabditis elegans (ref. ID; 506)

[Nickel(II) Chloride Hexahydrate]
Chemical formula; NiCl2/6H2O
Chemical characteristics; water soluble
Mode of action; Acts as an enzyme cofactor, effects on cellular iron levels and iron channels; carcinogen (ref. ID; 6758)
Test organisms;
Protozoa: Colpidium colpoda (ref. ID; 6111)
Protozoa: Dexiostoma campylum (ref. ID; 6111)
Protozoa: Euplotes moebiusi (ref. ID; 6111)
Protozoa: Euplotes patella (ref. ID; 6111)
Protozoa: Glaucoma scintillans (ref. ID; 6111)
Protozoa: Holosticha kessleri (ref. ID; 6111)
Protozoa: Loxodes striatus (ref. ID; 6111)
Protozoa: Paramecium bursaria (ref. ID; 6111)
Protozoa: Paramecium caudatum (ref. ID; 6111)
Protozoa: Paramecium putrinum (ref. ID; 6111)
Protozoa: Spirostomum teres (ref. ID; 6111)
Protozoa: Stylonychia pustulata (ref. ID; 6111)
Oligochaeta: Eisenia fetida (ref. ID; 6788)
Oligochaeta: Tubifex tubifex (ref. ID; 6968)
Nematoda: Caenorhabditis elegans (ref. ID; 6758)

[Nickel Nitrate]
Test organisms;
Protozoa: Euglena gracilis (ref. ID; 3548)
Nematoda: Caenorhabditis elegans (ref. ID; 3301, 6823)

[Ni(NO3)2]
Test organisms;
Protozoa: Colpidium campylum (ref. ID; 6081)

[Nickel Sulphate]
Test organisms;
Protozoa: Colpoda steinii (ref. ID; 499)

[NiSO4]
Chemical characteristics; water soluble
Test organisms;
Oligochaeta: Eisenia fetida (ref. ID; 6866)

[Nickel(II) Sulfate Hexahydrate] CAS[10101-97-0] UN3077
Chemical formula; NiSO4/6H2O
Chemical characteristics; water soluble
Test organisms;
Nematoda: Caenorhabiditis elegans (ref. ID; 6824)

[NiSO4/7H2O]
Test organisms;
Oligochaeta: Tubifex tubifex (ref. ID; 6079, 6080)

[Sediment Ni pollution]
Test organisms;
Oligochaeta: Limnodrilus hoffmeisteri (ref. ID; 6782)

[Soil Ni pollution]
Test organisms;
Oligochaeta: Allolobophora tuberculata (ref. ID; 6104)

[Nickel bis(dimethyldithiocarbamate)]
Trade name; nickel dimethyldithiocarbamate (J): DDC-Ni, Sankel
Chemical formula; C6H12N2NiS4
Purpose for use; bactericide
Toxicity; LD50 (oral): mouse 5200 mg/kg