SYMPOSIA PAPER Published: 01 January 1985
STP36268S

Comparison of System Design and Reproducibility to Estimate Bioconcentration of Di- -hexylphthalate by

Source

Duplicated flow-through exposure systems consisting of two diluters, operated simultaneously, were used to compare the bioconcentration of 14C-di-n-hexylphthalate (14C-DHP) by Daphnia magna under single-species (modular) or multispecies (mixed) model formats proposed for use as microcosms to estimate bioconcentration.

Triplicate exposures of Daphnia in each diluter system were made under conditions which provided the following possible sources of DHP: (1) water only fed (Daphnia in mixed model fed unlabeled algae), (2) water only unfed, (3) water plus food (labeled algae), and (4) food only.

Water levels of 14C-DHP were maintained at approximately 0.22 μg/L. Algae (Selenastrum capricornutum), previously exposed in water with 0.08 µg/L 14C-DHP and used to feed Daphnia, contained approximately 0.11 µg 14C-DHP/g. Results at 24 h showed significantly (P < 0.05) higher accumulation of 14C-DHP in Daphnia exposed to the combination of contaminated food and water than any other treatment. Accumulation from exposures only to food was not different from controls. No differences were detected between the same treatments in the duplicate exposure systems. Coefficients of variation within a treatment combining replicates from both diluters (n ≥ 4) averaged 18% and ranged from 8 to 32%.

Exposures to 14C-DHP in water only (Daphnia fed) were conducted in a mixed model system wherein Daphnia were subjected to controlled predation by bluegill sunfish (Lepomis macrochirus). Results from the mixed model systems suggested that steady-state accumulation took longer than seven days to achieve. The measured bioconcentration factor (BCF) of 3250 for 14C-DHP in D. magna was similar to values reported for other phthalate esters in microcrustaceans.

Measured BCFs for the water only (48 h), food plus water (48 h), and the mixed model system (14 days) were 1066, 1486, and 3254, respectively. Calculated BCFs, using a first-order steady-state equilibrium model were 998, 1414, and 4655, respectively, for the same three treatments. All BCFs reported are for total 14C activity on a wet-weight basis.

Author Information

Gloss, SP
New York Cooperative Fishery Research Unit, Cornell University, Ithaca, N.Y.
Biddinger, GR
New York Cooperative Fishery Research Unit, Cornell University, Ithaca, N.Y.
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Developed by Committee: E47
Pages: 202–213
DOI: 10.1520/STP36268S
ISBN-EB: 978-0-8031-4922-9
ISBN-13: 978-0-8031-0410-5