Waiving chronic fish tests: possible use of acute-to-chronic relationships and interspecies correlations

Figures & data

Table 1. Linear relationships between Daphnia acute or chronic toxicity data and fish chronic toxicity data.

			Geometric mean by MOA
	Lowest value	Geometric mean	MOA 1	MOA 2	MOA 3	MOA 4	MOA 5
LC50 Daphnia
n	246		62	42	27	52	63
p Value	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	0.0004	<0.0001
r^2	0.60	0.64	0.79	0.36	0.83	0.22	0.66
Outlier	1	1	2	0	0	0	0
Names and MOA of outliers	17β-estradiol (MOA 2)		Propanil; peracetic acid
NOEC Daphnia
n	193		52	36	23	34	48
p Value	<0.0001	<0.0001	<0.0001	0.0001	<0.0001	0.5168	<0.0001
r^2	0.56	0.59	0.66	0.35	0.65	0.01	0.67
Outliers	1	2	0	0	0	0	0
Names and MOA of outliers	17β-estradiol (MOA 2)		17β-estradiol (MOA 2); fenitrothion (MOA 4)

Figure 1. Relationships between Daphnia 48 h LC₅₀ (a) and Daphnia NOEC (b) and fish NOEC values with the geometric mean approach. The dashed lines represent the 95% confidence interval. Italics: name of the outliers.

Figure 2. Relationships between Daphnia LC₅₀ and fish NOEC values by MOA. Italics: name of the outliers; (a) all MOA; (b) MOA 1, r² = 79; (c) MOA 3, r² = 0.83.

Figure 3. Relationships between Daphnia NOEC and fish NOEC values by MOA. Italics: name of the outliers; (a) all MOA; (b) MOA 1, r² = 0.66; (c) MOA 3, r² = 0.65.

Figure 4. Sensitivity ratio derived with acute Daphnia data versus chronic fish data (black bar) and chronic Daphnia data versus chronic fish data (grey bar) in percentage of chemicals of the whole dataset; i.e. 34.7% of the chemicals demonstrate a higher chronic toxicity in Daphnia compared to NOEC fish and values range within a factor of 10; for 39% of the chemicals, the acute Daphnia LC₅₀ indicates a lower sensitivity compared to chronic NOEC fish and values range within a factor of 10.

Table 2. Substances with a high interspecies sensitivity ratio (SR_ch).

		CAS number	Name	MOA	SRch
Daphnia more sensitive	0.00001/0.0001	122-14-5	Fenitrothion	4	0.00003
	0.0001/0.001	333-41-5	Diazinon	4	0.000224
		298-04-4	Disulfoton	4	0.000443
		298-46-4	Carbamazepine	5	0.000978
	0.001/0.01	108-42-9	3-Chloroaniline	2	0.001455
		591-27-5	3-Amino-phenol	2	0.002
		298-00-0	Methyl parathion	4	0.002919
		95-53-4	o-Methylaniline	2	0.003508
		624-92-0	Dimethyl disulphide	3	0.003757
		106-49-0	p-Methylaniline	2	0.003939
		63-25-2	Carbaryl	4	0.004048
		62-53-3	Aniline	2	0.007719
Daphnia less sensitive	100/1000	15687-27-1	Ibuprofen	1	200
		57-63-6	Ethinyl estradiol	2	359
		1897-45-6	Chlorothalonil	4	466
		68-22-4	Norethindrone	5	670
	1000/10,000	138261-41-3	Imidacloprid	4	3505
	10,000/100,000	50-28-2	17β-Estradiol	2	26,912

Figure 5. Distribution of the chronic sensitivity ratios between Daphnia NOEC and fish NOEC according to their MOA.

Table 3. Linear relationships between acute fish data and chronic fish data.

			Geometric mean, by MOA
	Lowest value	Geometric mean	MOA 1	MOA 2	MOA 3	MOA 4	MOA 5
n	240		62	44	30	50	54
p Value	<0.0001	<0.0001	<0.0001	0.0001	<0.0001	<0.0001	<0.0001
r^2	0.82	0.87	0.83	0.83	0.88	0.85	0.88
Outliers	3	4	4	1	0	2	0
Names and MOA of outliers	MOA 1: propanil; MOA 4: chlorothalonil	MOA 1: propanil; MOA 2: 2-naphtol; MOA 4: ethyl parathion, chlorothalonil	Propanile, monoethanolamine, genistein, n-methylisopropylamine	2-Naphtol		Ethyl parathion, chlorothalonil

Figure 6. Relationships between fish 96 h LC₅₀ and fish NOEC values with the geometric mean approach. The dashed lines represent the 95% confidence interval. Italics: name of the outliers.

Figure 7. Relationship between fish 96 h LC₅₀ and fish NOEC values by MOA. The dashed lines represent the 95% confidence interval; (a) all MOA; (b) MOA 3, r² = 0.88; (c) MOA 5, r² = 0.88.

Table 4. Name and mode of action (MOA) of chemicals with Acute to Chronic Ratio (ACR) < 1.

	CAS number	Name	MOA	ACR
ACR < 1	4747-21-1	n-Methylisopropylamine	1	0.15
	108-18-9	Diisopropylamine	1	0.51
	137-30-4	Ziram	4	0.54
	106-93-4	1,2-Dibromoethane	1	0.54
	70124-77-5	Flucythrinate	5	0.67
	107-51-7	Octamethyltrisiloxane	5	0.77
	110-86-1	Pyridine	2	0.91

Figure 8. Acute-to-chronic fish toxicity ratio distribution.

Table 5. Name and mode of action (MOA) of chemicals with acute-to-chronic ratio (ACR) >100.

	CAS number	Name	MOA	ACR
100/1000	181587-01-9	5-Amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-(ethylsulfinyl)-1H-pyrazole-3-carbonitrile	4	134
	2212-67-1	Molinate	4	155
	330-54-1	Diuron	1	161
	124-40-3	Dimethylamine	1	192
	606-20-2	2,6-Dinitrotoluene	5	193
	1912-24-9	Atrazine	5	232
	79-21-0	Peracetic acid	1	270
	67-68-5	Dimethyl sulfoxide	5	340
	95-76-1	3,4-Dichloro-aniline	2	430
	944-22-9	Fonofos	4	468
	98-54-4	4-tert-butylphenol	2	521
	446-72-0	Genistein	1	723
	141-43-5	Monoethanolamine	1	738
1000/1000	56-38-2	Ethyl parathion	4	2962
	135-19-3	2-Naphthol	2	3458
	1897-45-6	Chlorothalonil	4	4646
>10,000	709-98-8	Propanil	1	14,906

Figure 9. Acute-to-chronic fish toxicity ratio distribution according to the MOA.