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Table 3 Cox PH model summary of the effect of pulse duration on the hazard of pesticide mixture

From: Survival analysis of African catfish and Nile tilapia briefly exposed to complex pesticide mixtures

Pesticide

Species

df

Parameter estimate

SE

Chi-square

Hazard ratio

Atrazine-Mancozeb

African catfish*

15 min

1

 − .482b

.913

.279

.618b

30 min

1

 − 1.168b

1.155

1.022

.311b

45 min

1

 − 1.138b

1.155

.972

.320b

60 min

3

  

1.596

 

Tilapia*

15 min

1

 − .754b

.707

1.137

.470b

30 min

1

 − .843b

.708

1.418

.431b

45 min

1

 − .054b

.577

.009

.947b

60 min

3

  

2.397

 

Atrazine-Chlorpyrifos

African catfish*

15 min

1

.423b

.646

.429

1.526b

30 min

1

.559b

.627

.795

1.749b

45 min

1

.610b

.627

.947

1.840b

60 min

3

  

1.076

 

Tilapia

15 min

1

 − 1.931a

.571

11.455

.145a

30 min

1

 − 1.612a

.493

10.675

.199a

45 min

1

 − 1.242a

.448

7.679

.289a

60 min

3

  

18.875

 

Atrazine-Lambda cyhalothrin

African catfish*

15 min

1

 − .998b

.690

2.092

.369b

30 min

1

 − .453b

.586

.599

.636b

45 min

1

 − .431b

.586

.540

.650b

60 min

3

  

2.194

 

Tilapia

15 min

1

 − 2.279a

.758

9.054

.102a

30 min

1

 − 1.561a

.568

7.550

.210a

45 min

1

 − .793b

.444

3.196

.452b

60 min

3

  

14.563

 

Mancozeb-Chlorpyrifos

African catfish*

15 min

1

 − .741b

.866

.732

.477b

30 min

1

 − .334b

.764

.191

.716b

45 min

1

 − .026b

.707

.001

.974b

60 min

3

  

.921

 

Tilapia

15 min

1

 − 1.303b

.678

3.694

.272b

30 min

1

 − .925b

.613

2.279

.396b

45 min

1

 − .932b

.613

2.314

.394b

60 min

3

  

5.206

 

Mancozeb-Lambda cyhalothrin

African catfish*

15 min

1

 − .760b

.707

1.154

.468b

30 min

1

 − .477b

.646

.547

.620b

45 min

1

 − .471b

.646

.533

.624b

60 min

3

  

1.361

 

Tilapia

15 min

1

 − 2.315a

.767

9.116

.099a

30 min

1

 − 1.549a

.581

7.111

.212a

45 min

1

 − 1.131a

.503

5.051

.323a

60 min

3

  

14.770

 

Chlorpyrifos-Lambda cyhalothrin

African catfish*

15 min

1

 − 1.144a

.534

4.591

.319a

30 min

1

 − .834b

.502

2.768

.434b

45 min

1

 − .557b

.457

1.487

.573b

60 min

3

  

5.718

 

Tilapia*

15 min

1

 − 2.146a

.765

7.868

.117a

30 min

1

 − .644b

.476

1.828

.525b

45 min

1

.084b

.401

.044

1.087b

60 min

3

  

10.384

 

Quaternary

African catfish*

15 min

1

 − 1.090a

.542

4.051

.336a

30 min

1

 − .784b

.509

2.374

.457b

45 min

1

 − .797b

.509

2.446

.451b

60 min

3

  

5.407

 

Tilapia*

15 min

1

 − 1.268b

.817

2.409

.281b

30 min

1

 − .855b

.707

1.460

.425b

45 min

1

 − .326b

.606

.290

.722b

60 min

3

  

3.104

 
  1. *Hazard ratio constant with time; a- indicates statistical significance (p < 0.05); b- indicates not significant (p > 0.05)