4,4'-isopropylidenediphenol

Biodegradation in soil

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Guideline:

other: Laboratory simulation of soil die-away tests

GLP compliance:

yes

Test type:

laboratory

Radiolabelling:

yes

Oxygen conditions:

aerobic

Soil classification:

other:

DT50:

< 3 d

Type:

(pseudo-)first order (= half-life)

Remarks on result:

other: Across four soil types

Transformation products:

not measured

EXTRACTABILITY OF BPA FROM SOIL:

14C-BPA in contact with soil rapidly forms non-extractable residues: After 1 h, 19 to 59% applied radioactivity, at all other times, 78 to 90% of applied radioactivity.

Hot-reflux extractions yielded only up to an additional 2.8% of applied radioactivity. Organic and hot-reflux extractions were combined to yield only 7.4% or less of applied radioactivity. By day 120, <2% of applied radioactivity was extractable in any soil.

According to the authors, "Therefore, it can be stated that the major route of 14C-BPA dissipation in soil results in the conversion to bound, non-extractable residues independent from the soil type used in this experiment."

BIODEGRADATION OF BPA IN SOIL:

At day 120, the extent of mineralization to 14CO2 reached 13.1 to 19.3%.

Based on TLC analyses, across all soil types, up to five metabolites were found in soil extracts taken at 1-2 hours. Also at 1-2 hours, between 21 to 66% of applied radioactivity was found as unchanged 14C-BPA. No 14C-BPA or any metabolite was detectable at day 3 indicating that the metabolites are transient and are not persistent.

A dissipation half-life of <3 days was estimated.

Material balance was in the range of 90.3 to 101% of applied radioactivity.

The major route of radiolabeled BPA in soil is the conversion to bound, non-extractable residues. These residues consist of the radiolabled material that remains following exhaustive sequential extraction with organic solvents. This phenomenon is common for phenolics.

Organic compounds like phenolics form bound residues in soils by a) formation of stable covalent bonds with organic substances, b) polymerization with soil to form soil organic matter, or c) cation exchange.

Bound residues of BPA in soil would be essentially non-bioavailable. Any bound residues release from soil would continue mineralization to carbon dioxide.

Executive summary:

Bisphenol A dissipates in soil in less than 3 days, with a major route being conversion to non-extractable bound residues.

Description of key information

Bisphenol A dissipates in soil in less than 3 days, with a major route being conversion to non-extractable bound residues.