Environmental Terms and Definitions

Detection limit
The smallest amount of substance that a laboratory test can reliably measure in a sample of air, water, soil or other medium.

Remedial Investigation (RI)
An in-depth study (including sampling of air, soil, water and waste) of a contaminated site needing remediation to determine the nature and extent of contamination. The remedial investigation (RI) is usually combined with a feasibility study (FS).

Analyte
A chemical for which a sample (such as water, air, blood, urine or other substance) is tested. For example, if the analyte is mercury, the laboratory test will determine the amount of mercury in the sample.

Concentration
Any substance that enters a system (the environment, human body, food, etc.) where it is not normally found. Contaminants are usually referred to in a "negative" sense and include substances that spoil food, pollute the environment or cause other adverse effects.

HMIS
The hazardous materials identification system, developed by NPCA to provide information on the acute health hazards, reactivity, and flammability encountered in the workplace at room temperatures.

Health registry
A record of people exposed to a specific substance (such as a heavy metal), or having a specific health condition (such as cancer or a communicable disease). New York State maintains several health registries.

Gradient
The change in a property over a certain distance. For example, lead can accumulate in surface soil near a road due to automobile exhaust. As you move away from the road, the amount of lead in the surface soil decreases. This change in the lead concentration with distance from the road is called a gradient.

Superfund (federal and state)
The federal and state programs to investigate and clean up inactive hazardous waste sites.

AHM
Acutely Hazardous Material

Maximum Contaminant Level (MCL)
The highest (maximum) level of a contaminant allowed to go uncorrected by a public water system under federal or state regulations. Depending on the contaminant, allowable levels might be calculated as an average over time, or might be based on individual test results.