Herbicide concentrations in waterways following aerial application in a steepland planted forest in New Zealand

New Zealand Journal of Forestry Science

Table 1 Freshwater environmental and toxicology data for hexazinone and terbuthylazine (MacBean 2012; Ministry of Health, 2008; University of Hertfordshire, 2015; World Health Organization, 2011). Updated from Table 1 in Baillie et al. (2015)

Herbicide	Water solubility	Half-life in water (DT₅₀)	EC₅₀ ^a algae	LC₅₀ ^b (48 h) Daphnia	LC₅₀ (96 h) rainbow trout	K _ow ^c log	BCF^d	DWS^e New Zealand	DWS WHO
Herbicide	mg L⁻¹	days	μg L⁻¹	μg L⁻¹	μg L⁻¹			μg L⁻¹	μg L⁻¹
Terbuthylazine	9	33–73	16	>69,300	220	3.4	34	8	7
Hexazinone	29,800	56	7–210	152,000	>320,000	1.2	7	400	–

^aEC₅₀ is the median effective concentration for a specified time: 72 h for terbuthylazine and 120 h for hexazinone
^bLC₅₀ (lethal concentration) is the concentration in water that kills 50 % of the test organisms
^c K _ow (octanol/water partition coefficient) is the ratio of the concentration of a chemical in octanol and in water at equilibrium
^d BCF bioaccumulation factor
^e DWS drinking water standards