Table 3. Median Cytotoxic Concentrations (EC₅₀) of Benzalkonium Chlorides (BAC) Differing in Alkyl Chain Length^a.

		medium without supplements		medium with 60 μM BSA	medium with 10% serum
BAC (alkyl chain length)	EC50 ± SE (μM, nominal)	EC50 ± SE (μM, measured t = 0 h)	EC50 ± SE (μM, measured t = 48 h)	EC50 ± SE (μM, measured t = 48 h)	EC50 ± SE (μM, measured t = 48 h)
6	247.90 ± 2.94	199.10 ± 4.36	195.10 ± 4.36	305.30 ± 2.32	452.00 ± 5.39
8	30.86 ± 0.73	32.86 ± 0.70	25.01 ± 0.63	35.59 ± 0.78	61.83 ± 1.24
10	1.27 ± 0.74	1.18 ± 0.76	0.89 ± 1.02	3.03 ± 0.29	8.09 ± 0.21
12	0.46 ± 0.04	0.27 ± 0.02	0.11 ± 0.01	1.47 ± 0.56	2.28 ± 0.20
14	1.30 ± 0.28	0.45 ± 0.04	0.05 ± 0.00	0.79 ± 0.33	1.05 ± 1.39
16	0.70 ± 0.40	0.47 ± 0.17	0.04 ± 0.00	0.82 ± 0.37	0.75 ± 0.26
18	1.73 ± 0.32	0.48 ± 0.12	0.07 ± 0.01	1.08 ± 1.61	1.62 ± 0.57

^aEC₅₀’s were calculated using three different dose metrics. Cytotoxicity to RTgill-W1 for each BAC was determined using three replicate CFDA-AM assays. BACs were exposed to cells in medium containing no supplements (EC₅₀ in μM measured at t = 48 h), containing 60 μM (4 g/L) BSA (EC₅₀ in μM measured in medium with 60 μM BSA).