Environmental testing and analytical services provide testing of environmental samples such as soil, water, air, and industrial wastes or byproducts. This product area covers soil testing, water testing, air testing, hazardous waste testing and cell testing services. Soil testing may require the analysis of samples from multiple locations and depths. Environmental testing services determine soil acidity and soil alkalinity (pH), as well as levels of plant nutrients such as nitrogen (N), phosphorous (P), and potassium (K). An environmental testing service that handles biological tissues or medical wastes should follow specific procedures for submitting samples to laboratories. Some environmental testing and analytical services specialize in antibiotics, mycotoxins, or indoor air quality (IAQ). Others specialize in the testing and analysis of wastewater, pesticide residues, or feed ingredients.