SIDS INITIAL ASSESSMENT PROFILE
2(3H)-Furanone, dihydro-3-hydroxy-4,4-dimethyl (DL-lactone)
SUMMARY CONCLUSIONS OF THE SIAR
There is no information on the toxicokinetics of DL-lactone available.
The acute oral LD50 of DL-lactone in rats and mice is above 2000 mg/kg bw.
In a test with rabbits (OECD 404) DL-Lactone was not irritating to the skin. However, based on occupational exposure experience in humans, DL-lactone is expected to be irritating to the eyes and upon prolonged and intensive exposure also to the skin. No sensitisation potential is found in the guinea-pig maximisation test (OECD 406).
In a combined repeated dose reproduction/developmental toxicity screening study (OECD 422) female rats treated at an oral dose of 1000 mg/kg bw/day showed aggression and restlessness during part of the study period. Findings on body weight, food consumption, haematology, clinical chemistry, organ weights, macroscopy and histopathology were within normal ranges. The NOAEL for repeated dose toxicity was set at 200 mg/kg bw/day.
DL-lactone was negative in an Ames test (OECD 471) and an in vivo micronucleus test (OECD 474). There are no indications that DL-lactone possesses mutagenic properties.
In an OECD 422 repeated dose reproduction/developmental toxicity screening study with rats exposed to DL- lactone, no effects on reproductive performance, stage of spermatogenesis, pup mortality, weight, sex and viability were reported up to oral doses of 1000 mg/kg bw/day. Animals were dosed prior to and during mating, gestation and following gestation until lactation day 4. Based on the available data, DL-lactone does not show evidence of reproductive or developmental toxicity. The NOAEL for reproductive toxicity is ≥1000 mg/kg bw/day.
DL-lactone is a white crystalline powder with a melting point of 78°C, boiling point of 247°C and a vapour pressure of about 0.1 hPa at 25°C (calculated from experimental vapour pressure at 60°C). The substance is very soluble in water (> 500 g/l) and has a log Kow of -0.69 (OECD 107). Based on its pKa (>13) DL-lactone is most likely present in the unionised form under environmental conditions. The substance is readily biodegradable. Hydrolysis half-live for DL-lactone is expected to be one year at pH 4, 30 days at pH 7 and approximately 12 days at pH 9 (25°C).
Various model calculations (based on log Kow) indicate that DL-Lactone does not bioaccumulate in fish and/or
DL-lactone has an LC50
of >140 mg/L in fish, an EC50
of >130 mg/L in daphnia and an EC50
for biomass and
growth rate of >78 mg/L (nominal 100 mg/L) in algae. Data on the toxicity towards micro-organisms of the d-