Did you already check the EPA or WHO websites for this information?

That is the first (logical) step to take.

you have to enter in the EPA web page

EPA /WHO   details are available on line,

I Also suggest that you should check EPA and ATSDR 

Also go for toxicological profile for each metal

This PDF material will assist you in what you are looking for.

Best regards

As = 1-40 mg/kg;  Cd = 0.01-0.7 mg/kg ; Cr = 1-1000 mg/kg ; Cu = 2-100 mg/kg ; Ni = 5-500 mg/kg ; Pb = 2-200 mg/kg ; Zn = 10-300 mg/kg.

see also attached file

• 2 words  penaeus semisulcatus

Dear Linus Aposu

Maximal permissible addition MPA of heavy metals and metalloids (mg/kg) 

Metal/metalloid

MPA

Beryllium (Be)

0.0061

Selenium (Se)

0.11

Thallium (Tl)

0.25

Antimony (Sb)

0.53

Cadmium (Cd)

0.76

Vanadium (V)

1.1

Mercury (Hg)

1.9

Nickel (Ni)

2.6

Copper (Cu)

3.5

Chromium (Cr)

3.8

Arsenic (As)

4.5

Barium (Ba)

9.0

Zinc (Zn)

16

Cobalt (Co)

24

Tin (Sn)

34

Lead (Pb)

55

Molybdenum (Mo)

253

Dear Linus Aposu

You can following the attached paper too.

regards

You can check the EPA or WHO sites also here you can find the files attached by my colleagues.

Regards

You can also have  a look on this paper :

https://www.researchgate.net/publication/309463664_Environmental_Assessment_of_Heavy_Metal_Pollution_and_Human_Health_Risk

regards

Article Environmental Assessment of Heavy Metal Pollution and Human ...