Manganese

Endpoint summary

Description of key information

Bioaccumulation: aquatic / sediment:

Study was conducted to determine the bioaccumulation of test chemical in Asterias rubens. The Bioaccumulation factor (BCF) for the substance was determined to be 19 in  , 14, 13 and 61 for 1.0 mg/l and  19, 14, 13 and 61 dimensionless for 0.4 mg/l concentration in tissue, Pyloric caeca, stomach and tube feet respectively after 23 days.

Additional information

Bioaccumulation: aquatic / sediment:

Following different studies includes experimental study for the target chemical  to observe the bioaccumulation rate test chemical in aquatic/ sediments.

First study was conducted to determine the bioaccumulation of test chemical in Asterias rubens. 1.0 mg /l was studied in two groups of 30 sea stars body wt of 10 + 7 g and length 5-13 cm held in 40 1 glass aquaria. One of the aquaria served as a control. Six specimens were collected from each experimental group on days 0, 7, 14, 21 and 28 of the exposure. The tissue samples were frozen at -18°C and freeze-dried for manganese determination. organism were acclimated in the laboratory for 7 days prior to experiments. Test chemical was analyze by takingupto 100 mg of freeze-dried tissue weighed in a Pyrex glass tube. Sixty-five percent HNO 3 (Merck p.a.)(2.0 ml) was added and the samples were heated stepwise to about 140-180°C for 3-5 days until the liquid was evaporated to dryness. After cooling, 2.0 ml of 0.2% HNO 3 was added. The manganese concentration in the resulting solution was determined on a Perkin- Elmer 2380 atomic absorption spectrophotometer. Air-acetylene flame and deuterium background correction were used.

After the exposure of test chemical with Asterias rubens, it was observed that the chemical is non-bioaccumulative as bioaccumulation factor (BCF) for the substance was determined to be 19 in  , 14, 13 and 61 for 1.0 mg/l and  19, 14, 13 and 61 dimensionless for 0.4 mg/l concentration in tissue, Pyloric caeca, stomach and tube feet respectively after 23 days.

Second study was perfomed to determine bioaccumulation of test chemical in aquatic orgamism. Bluegill, Warmouth, Largemouth bass, Chain pickerel, Redfin pickerel, American eel, Lake chubsucker were used as test orgamism. Organisms were collected from an acidic, highly organic pond. Study was conducted at 5-31°C, pH of 4.2-5.0 and at 4.6-9.2 dissolved oxygen for 500 days. The test was performed in stainless steel implements, Polyethylene gloves, ice-filled chests, porcelain crucibles, polyethylene bottles. samples of bluegill from Indiana Lakes and Skinface Pond were compared. Resident fishes from Skinface Pond were collected and were transported to the laboratory in ice-filled chests, placed in polyethylene bags, and stored at -4°C until lyophilization. Liver and axial muscle tissues of fish were dissected with stainless steel implements on a clean polyethylene work surface. Polyethylene gloves were worn during dissection of fish tissues to reduce surface contamination of samples. After dissection, tissue samples were placed in washed and tared plastic vials, weighed, and lyophilized to a constant dry weight. Whole fish were dried, digested, and analyzed by atomic absorption spectrophotometry. Sample preparation and analytical procedures were evaluated and validated, using U.S. National Bureau of Standards (NBS) bovine liver as a reference material. Bioaccumulation of the test chemical was calculated on the basis of whole body concentration of bluegill from lakes of Indiana after 500d, which was determined to be 220. Mn concentrations did not vary with body size in liver tissue or axial musculature. Similarly, mean axial muscle and whole body concentration of Mn in stocked bluegill were relatively constant approximately 200 d after stocking and did not change substantially with growth. Hence, this metal did not accumulate in the tissues with age.

In next the test was conducted to determine bioaccumulation value of test chemical in test organism. 14 months old American Oyster,Crassostrea virginica of 36±1 mm length and 0.123±0.019 gm in weight was used as test organism in study. Organisms were collected form Smithsonian Chesapeake Bay Center for Environmental Studies (CBCES) in the Rhode River.Oysters were derived from a single parent pair, thus increasing genetic homogeneity. Test was performed inPlastic trays. Two groups of each tray contain 5 oyster shells. Each oyster was thoroughly washed and shucked. The entire soft body tissue was removed and allowed to drain for 5 minutes and then placed in a pre-weighed plastic container and sealed. The wet weight of organism was determined and then the was sample frozen. The samples were freeze-dried for 48 hours and a dry weight of sample was determined. Concentrations are expressed on a dry weight basis to reduce errors associated with random retention of body liquors. Correlation coefficients between oyster soft tissue metal concentration and shell growth rate as measured by rate of change in shell height, for Mn was 0.76. A high rate of turnover of Mn in soft tissue occurs during the shell growth season and tissue levels are controlled by the small difference between two high rates, the soft tissue uptake rate and the shell deposition rate. Bioaccumulation value of test chemical in American Oyster, Crassostrea virginica was observed to be 3.02mg for 12 months (annual cycles).

On the basis of above experimental studies of test chemical, the test chemical considere to be non-bioaccumulative in nature.