yman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 4-9, 15-1 to 15-29 (1990) (4) Budavari S, ed; The Merck Index. 12th ed Whitehouse Station, NJ: Merck and Co., Inc., p. 1 (1996) (5) Franke C et al; Chemosphere 29: 1501-14 (1994) (6) Vandenheuvel WJA et al; Environ Toxicol Chem 15: 2263-2266 (1996) (7) EXTOXNET; Extension Toxicology Network. Cornell Univ. Pesticide Information Profile Database on Abamectin (71751-41-2). Available from the database query page at: http://pmep.cce.cornell.edu/profiles/extoxnet/24d-captan/abamectin-ext.html as of Jan 3, 2001.] **PEER REVIEWED**

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), abamectin, which has a vapor pressure of 1.5X10-9 mm Hg(2) is expected to exist solely in the particulate phase in the ambient atmosphere. Particulate-phase abamectin may be removed from the air by wet and dry deposition(SRC). There is the potential for the photodegradation of abamectin in air(3,4); however, the rate at which this process may occur is not known.
[(1) Bidleman TF; Environ Sci Technol 22: 361-367 (1988) (2) Budavari S, ed; The Merck Index. 12th ed Whitehouse Station, NJ: Merck and Co., Inc., p. 1 (1996) (3) Demchak RJ, Dybas RA; J Agric Food Chem 45: 260-262 (1997) (4) Peterson RF et al; Photolytic Degradation of Formulated Avermectins: Effect of p-Aminobenzoic Acid (PABA). ASTM Spec Tech Publ 1268: 88-96 (1996)] **PEER REVIEWED**


Environmental Biodegradation:
AEROBIC: Soil half-lives of 2 weeks to 2 months have been reported; loss of abamectin in soils is thought to be due to microbial degradation as no loss has been observed in sterile soils(1). ANAEROBIC: The rate of degradation in soil was decreased substantially under anaerobic conditions(1).
[(1) EXTOXNET; Extension Toxicology Network. Cornell Univ. Pesticide Information Profile Database on Abamectin (71751-41-2). Available from the database query page at: http://pmep.cce.cornell.edu/profiles/extoxnet/24d-captan/abamectin-ext.html as of Jan 3, 2001.] **PEER REVIEWED**


Environmental Abiotic Degradation:
Abamectin is stable to hydrolysis at pH levels of 5, 7 and 9(1). Abamectin photodegrades rapidly in the environment, in water, on soil and in the atmosphere, with a half-life of approximately 2-6 hours observed for a thin film on inert (glass) or leaf surfaces(2). Photodegradation of abamectin involves the oxidation of the diene chromophore of the avermectin B1a component of the mixture(3).
[(1) Tomlin CDS; Pesticide Manual. 11th ed p. 4 (1997) (2) Peterson RF et al; Photolytic Degradation of Formulated Avermectins: Effect of p-Aminobenzoic Acid (PABA). ASTM Spec Tech Publ. 1268: 88-96 (1996) (3) Demchak RJ, Dybas RA; J Agric Food Chem 45: 260-262 (1997)] **PEER REVIEWED**


Environmental Bioconcentration:
Abamectin accumulated in bluegill sunfish exposed to a mean aqueous concn of 0.099 ug/l abamectin for 28 days; the BCF was reported as 56(1)