Table 6 Cox PH model summary of effect of pulse duration on hazard of single pesticide.

From: Assessment of the risk of death of Clarias gariepinus and Oreochromis niloticus pulse-exposed to selected agricultural pesticides

Pesticide

Species

df

Parameter estimate

SE

Chi-square

Hazard ratio

Atrazine

Catfish*

15 min

1

 − 1.300a

.484

7.221

.272a

30 min

1

 − .512b

.397

1.663

.599b

45 min

1

 − .928a

.438

4.483

.395a

60 min

3

  

9.001

 

Tilapia

15 min

1

 − .361b

.646

.313

.697b

30 min

1

.141b

.578

.060

1.152b

45 min

1

.051b

.577

.008

1.052b

60 min

3

  

.654

 

Mancozeb

Catfish

15 min

1

 − 1.945a

.518

14.123

.143a

30 min

1

 − 1.577a

.459

11.826

.206a

45 min

1

 − 1.519a

.458

11.007

.219a

60 min

3

  

23.341

 

Tilapia*

15 min

1

 − .351b

.646

.296

.704b

30 min

1

 − .412b

.646

.407

.662b

45 min

1

.037b

.577

.004

1.037b

60 min

3

  

16.070

 

Chlorpyrifos

Catfish*

15 min

1

 − 1.864a

.567

10.818

.155a

30 min

1

 − 1.418a

.488

8.444

.242a

45 min

1

 − .999a

.441

5.130

.368a

60 min

3

  

.779

 

Tilapia*

15 min

1

.246b

.317

.601

1.279b

30 min

1

.045b

.316

.020

1.046b

45 min

1

.836a

.334

6.249

2.307a

60 min

3

  

7.694

 

Lambda cyhalothrin

Catfish

15 min

1

 − 1.994a

.499

15.958

.136a

30 min

1

 − 1.179a

.411

8.227

.308a

45 min

1

 − 1.710a

.489

12.202

.181a

60 min

3

  

20.231

 

Tilapia*

15 min

1

 − .547b

.465

1.385

.579b

30 min

1

 − .410b

.450

.832

.663b

45 min

1

 − .234b

.437

.286

.791b

60 min

3

  

1.604

 
  1. *Hazard ratio constant with time.
  2. aStatistical significant (p < 0.05).
  3. bNot significant (p > 0.05).