Dangerous and offensive trades
Dangerous and offensive trades or offensive trades, are business activities that deal with processing dead animals or that generate unpleasant smells, are subject to regulation in many jurisdictions including India and former British possessions. Definition

The Oxford Dictionary of Public Health defines offensive trades as 

Such offensive industries can encompass a variety of commercial activities, but mainly involve the handling of animal carcasses and hides. Their regulation is aimed at public health, addressing risks such as physical risk of injury or death, chemical risks from natural or synthetic substances used, or biological risk from pathogens and vermin. History

The regulation of offensive trades dates back at least to the Sanitary movement in the mid-1800's and the passage of the Nuisances Removal and Diseases Prevention Acts which regulated certain trades in cities in the United Kingdom as part of an effort to address the problem of cholera. Individual Countries

Barbados
In Barbados, the following are considered offensive trades:
Blood or offal boiling 
Bone boiling or crushing 
Chemical or acid making 
Fellmongering 
Glue making 
Gut spinning 
Gut scraping 
Manure manufacturing 
Slaughtering 
Soap boiling 
Tallow melting 
Tanning

India
They are classified under the Municipalities of India by an Act passed by the Legislature of India requires licensing and this also serve as a source of income for the states and municipalities. The trades practiced by the traders are called as "D & O Traders". References

Indian legislation