Table 2. Typical metabolic reactions of pesticides in birds.

Oxidation		Reduction		Hydrolysis (Bond cleavage)
O1	Alkyl oxidation/O (N)-dealkylation	R1	Reductive dehalogenation	H1	Carboxyl ester
O2	Aryl hydroxylation	R2	Dehydrohalogenation	H2	Amide, imide, carbamate, urea
O3	Epoxidation	R3	Multiple bond (–=N–, –C=C–, C=O)	H3	(Oxime, thio) Ether
O4	S-oxidation	R4	Nitro group	H4	C(N)–C(N, S) bond
O5	Desulfuration (P=S, C–O3H)	R5	S-reduction	H5	Phosphoryl (sulfonyl) ester
Conjugation				H6	Dehalogenation/denitration
C1	Glucuronidation	C5	Acetylation	Miscellaneous
C2	Sulfation	C6	Methylation	M1	Rearrangement
C3	Glutathione*	C7	Other natural products (fatty acids, cholesterol etc.)	M2	Cyclization
C4	Amino acid			M3	Hydration/dehydration

*R-X+GSH → R-SG → R-Cys-Gly → R-Cys → R-(N-acetyl-Cys). R, alkyl or aryl; GSH, glutathione; Cys, cysteine; Gly: glycine.