Welcome to the WUSTL/Just Moms STL Hazardous Waste Database!

An easy to read database of EPA cleanup/toxicity levels for commonly encountered contaminants.


How to Use

In this database, each chemical contaminant has its own page with its specific screening and contaminant levels. Search for the desired chemical using the categories above or by using the search engine located on the top right corner of every page. For more background about the different types of levels and other information found on the chemical pages, please see the sections below.

Regional Screening Levels

The EPA has established Screening Levels that represent risk-based concentrations of hazardous chemicals.

Screening Levels are generic screening values, not cleanup standards, developed from exposure information and toxicity data. A contaminant concentration over the specified Screening Level may warrant further evaluation of the site. Screening levels are designed to be protective for humans over the course of their entire lifetime.

These levels can be used to “screen” a potential Superfund site and can be used as initial clean-up goals. However, these values are not site-specific and may need to be recalculated for a specific cleanup site. The values provided on this website represent the values for a target hazard quotient of 1.0 (THQ=1.0). This THQ value is typically used when screening for only one contaminant. If multiple contaminants are tested, it is preferred to use the THQ=0.1 table values which can be found at the source below.

Maximum Contaminant Level

The EPA has established drinking water regulations for more than 90 contaminants.

The Safe Drinking Water Act (SDWA) requires that the EPA identify and publish a list of unregulated contaminants. This is called the Contaminant Candidate List (CCL). Periodically, the EPA decides whether to regulate at least five or more contaminants on the list.

If the EPA decides to regulate a particular contaminant, they review health effects data in order to set a maximum contaminant level goal (MCLG). The MCLG is the “maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on the health of persons would occur, allowing an adequate margin of safety.” MCLGs are non-enforceable public health goals.

After setting an MCLG, the EPA sets an enforceable standard, a maximum contaminant level (MCL). The MCL is the “maximum level…allowed in water which is delivered to any user of a public water system.” The MCL is set as close to the MCLG as feasible.

If the EPA decides not to regulate a contaminant, they may develop a health advisory to serve as guidance for federal, state, and local officials. A health advisory is a non-enforceable federal limit.

Types of Media

In the Regional Screening Levels Table located on each chemical’s page, each level is specific to a different type of media, which is what contains the chemical contaminant and how it is consumed. The different types of media, along with a short description for each, is included in the table below:

MediaDescription
Resident SoilThe person affected by this media spends most, if not all, of the day at home. The activities for this person involve typical home making chores (cooking, cleaning and laundering) as well as outdoor activities. The resident is assumed to be exposed to contaminants in the following ways: accidental ingestion of soil, skin contact with soil, and breathing in of gases and dust.
Industrial SoilThe person affected by this media is exposed long-term during the work day, who is a full-time employee working on-site, and spends most of the workday conducting maintenance activities outdoors. The activities for this worker (e.g., moderate digging, landscaping) typically involve on-site exposure to surface soils. The worker is assumed to be exposed to contaminants in the following ways: accidental ingestion of soil, skin contact with soil, and inhalation of gases and dust. The worker in this situation is thought of following the most protective protocols of outdoor and indoor workers.
Resident AirThe person affected by this media spends most, if not all, of the day at home. The activities for this receptor involve typical home making chores (cooking, cleaning and laundering) as well as outdoor activities. The resident is assumed to be exposed to contaminants through the inhalation of ambient air.
Industrial AirThe person affected by this media is exposed long-term during the work day, who is a full-time employee working on-site, and spends most of the workday conducting maintenance activities indoors. The worker is assumed to be exposed to contaminants in the following ways: inhalation of ambient air. The worker in this situation is thought of following the most protective protocols of outdoor and indoor workers.
TapwaterThe person affected by this media is exposed to chemicals in water that are delivered into a residence from sources such as groundwater or surface water. Ingestion of drinking water is an appropriate pathway for all chemicals. Activities such as showering, laundering, and dish washing can put contaminants into the air that could be inhaled, so they are included in this media. Skin contact with tapwater is also considered.
Source: https://www.epa.gov/risk/regional-screening-levels-rsls-users-guide#resident (Edited for clarity)

Units

On each chemical page, there will be different concentration levels listed in various units. Reference the table below for more information about the different units used on this site.

AbbreviationMeaningNotes
mg/kgmass of chemical (milligrams, mg) per mass of soil (kilogram, kg)Equivalent to parts per million (ppm)
μg/m3mass of chemical (micrograms, mg) per volume of air (cubic meter, m3)This can be converted to ppm using the molecular weight of the chemical
μg/Lmass of chemical (micrograms, μg) per volume of water (liter, L)Equivalent to parts per billion (ppb); divide by 1,000 to get ppm
mg/Lmass of chemical (milligrams, mg) per volume of water (liter, L)Equivalent to parts per million (ppm)
pCi/Lradioactivity of chemical (picocuries, pCi) per volume of water (liter, L)A Curie is a unit of radioactivity equivalent to that of one gram of radium; pico means
one-trillionth
MFLamount of chemical (millions of fibers) per volume of water (liters, L)Asbestos is the name given to six minerals with long, thin fibers

For more information about these units and their conversion factors, visit https://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.files/fileid/14285.