Zeolite, cuboidal, crystalline, synthetic, non-fibrous

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

fish early-life stage toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: EPA: “Proposed Recommended Bioassay Procedures for Egg and Fry Stages of Freshwater Fish"

Version / remarks:

1972

Deviations:

not specified

GLP compliance:

not specified

Specific details on test material used for the study:

Type-A Zeolite

Analytical monitoring:

yes

Details on test solutions:

To avoid the effects of hardness ion depletion during all freshwater tests, including acutes, longer-term chronics and critical life stage testing, the zeolite used in these tests was pre-exchanged with Ca2+, Mg2+, Na+, and K+ ions. A 100-L batch of reconstituted water was prepared at 100x recommended salt concentrations. A 500-g sample of zeolite was added, mixed for 1 h, and allowed to settle. Three subsequent suspensions were mixed with new batches of reconstituted water until no further depletion in total hardness of Ca2+ concentration was
recorded. Atomic absorption analyses of the zeolite at this time indicated that 90% existed in the Ca2+ exchanged form with a total of 10% as Mg2+, Na+, and K+ salts. This exchange was deemed appropriate to model the environmental form of zeolite since it is highly unlikely that the sodium form of zeolite would predominate in natural surface waters.

Test organisms (species):

Pimephales promelas

Details on test organisms:

Eggs were obtained from the USEPA National Water Quality Laboratory in Duluth, Minn. Exposure of eggs in each test began within 48 h after fertilization.

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 d

Hardness:

in average 36 mg/L CaCO3

Test temperature:

21 +/- 1 °C

pH:

7.6 +/- 0.3

Dissolved oxygen:

>= 86%

Nominal and measured concentrations:

measures: 6.2, 12.3, 22.6, 86.7 mg/l
plus control group

Reference substance (positive control):

no

Key result

Duration:

30 d

Dose descriptor:

NOEC

Effect conc.:

>= 86.7 mg/L

Nominal / measured:

meas. (arithm. mean)

Basis for effect:

other: hatchability of eggs and survival, mean total length, weight

Details on results:

The results of the various biological data obtained from continuous-flow exposures of fathead minnow, Pimephales promelas, eggs and fry to suspensions of Ca-exchanged zeolite indicated no adverse effect on hatchability of eggs and survival, mean total length, and average weight of fry at 30 days post hatch.
The concentrations of test material in suspension varied considerably during the exposure period, reflecting the difficulty of maintaining uniform suspensions of these particulates and the propensity of the compounds to clump and settle on the exposed surface of the chambers. Highest zeolite concentrations varied from 33 to 182 mg/L with a mean of 87 mg/L. Thus, the observed no-effect concentration of MATC for zeolite with the fathead minnow was determined to be a concentration greater than the highest mean exposure of the material, 87 mg/L.

Validity criteria fulfilled:

not specified

Conclusions:

The results of the various biological data obtained from continuous-flow exposures of fathead minnow, Pimephales promelas, eggs and fry to suspensions of Ca-exchanged zeolite indicated no adverse effect on hatchability of eggs and survival, mean total length, and average weight of fry at 30 days post hatch. The mean NOEC was 87 mg/l.

Executive summary:

Partial chronic toxicity tests designed to include exposures of the sensitive egg and fry life stages of the fathead minnow, Pimephales promelas, were done with zeolite following methods modified from USEPA.

Description of key information

The results of the various biological data obtained from continuous-flow exposures of the freshwater fish fathead minnow, eggs and fry to suspensions of Ca-exchanged zeolite indicated no adverse effect on hatchability of eggs and survival, mean total length, and average weight of fry at 30 days post hatch. The mean NOEC was equal or greater than 86.7 mg/l.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

NOEC

Effect concentration:

>= 86.7 mg/L