US EPA

1510405 

Journal Article 

Use of Paramecium species in bioassays for environmental risk management: Determination of IC50 values for water pollutants 

Miyoshi, N; Kawano, T; Tanaka, M; Kadono, T; Kosaka, T; Kunimoto, M; Takahashi, T; Hosoya, H 

2003 

Yes 

Journal of Health Science
ISSN: 1344-9702
EISSN: 1347-5207 

49 

6 

429-435 

English 

10.1248/jhs.49.429 

WOS:000186838300003 

Effect of chemical water pollutants on the growth of two Paramecium species (Paramecium caudatum and Paramecium trichium) were examined. The chemicals
used as model chemical pollutants include organic solvents, potential carcinogens, mutagens, metabolic modulators, herbicides, insecticides, fungicides, antimicrobials, heavy metals, and heavy metal-containing chemicals. In this study, the IC50 values indicating the concentration of substances inhibiting the proliferation of Paramecium cells by 50% were used instead of the LD50 value, which indicates the dose of substances killing half the population of organisms, since the former is a more sensitive parameter for assessing the toxicity of substances at lower concentrations. Among 25 chemicals examined, di-(2-ethylhexy 1)phthalate, potassium dichromate, 2,4-dichlorophenoxy acetic acid, and paraquat stimulated the growth of paramecia depending on the concentrations used. Dimethyl sulfoxide and formaldehyde were shown to be inert to paramecia in
the range of concentrations (up to 1%, v/v) used here. Other chemicals were shown to inhibit the growth of the paramecia and thus the IC50 values for those chemicals were determined. Our data presented here may be a useful reference for assessing the impact of water pollutants on aqueous microecosystems consisting of various microorganisms including protozoa. 

IC50; model chemical pollutants; Paramecium species; protozoa; water pollution