The commercialised poultry production farms are usually very large. Giving medicine to every animal separately is too much work. Therefore when couples have to be vaccinated or medicine has to be given this is either done by putting the medicine in the drinking water or the animals are sprayed. Putting medicine in drinking water does not have an effect on the safety of the veterinarian or farmer. Veterinarians and farmers that have been in contact with medicine given through a spray can experience irritation of the eyes and/or irritation of the respiratory system. Long term effects are not present.