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Drinking Water Contaminants- Styrene


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What is Styrene and how is it used?

Styrene is an oily organic liquid with an aromatic, almost floral odor. Initially, styrene was used primarily in the synthetic rubber industry, but it is currently used as a building block for polymers in making plastics, resins, coatings, and paints.

The list of trade names given below may help you find out whether you are using this chemical at home or work.

Trade Names and Synonyms:

Vinyl benzene
Diarex HF 77

Why is Styrene being Regulated?

In 1974, Congress passed the Safe Drinking Water Act. This law requires EPA to determine safe levels of chemicals in drinking water which do or may cause health problems. These non-enforceable levels, based solely on possible health risks and exposure, are called Maximum Contaminant Level Goals.

The MCLG for styrene has been set at 0.1 parts per million (ppm) because EPA believes this level of protection would not cause any of the potential health problems described below.

Based on this MCLG, EPA has set an enforceable standard called a Maximum Contaminant Level (MCL). MCLs are set as close to the MCLGs as possible, considering the ability of public water systems to detect and remove contaminants using suitable treatment technologies.

The MCL has been set at 0.1 ppm because EPA believes, given present technology and resources, this is the lowest level to which water systems can reasonably be required to remove this contaminant should it occur in drinking water.

These drinking water standards and the regulations for ensuring these standards are met, are called National Primary Drinking Water Regulations. All public water supplies must abide by these regulations.

What are the Health Effects?

Short-term: EPA has found styrene to potentially cause the following health effects when people are exposed to it at levels above the MCL for relatively short periods of time: nervous system effects such as depression, loss of concentration, weakness, fatigue and nausea.

Long-term: Styrene has the potential to cause the following effects from a lifetime exposure at levels above the MCL: liver and nerve tissue damage; cancer.

How much Styrene is produced and released to the environment?

Production of styrene was 10.7 billion lbs in 1993. It is released into the environment by emissions and effluents from its production and its use in polymer manufacture. Consumers may be exposed to styrene through contact with resin products used in fiberglass boat construction and repair, and in auto body fillers. Styrene may also leach from polystyrene containers used for food products.

From 1987 to 1993, according to EPA's Toxic Chemical Release Inventory, styrene releases to land and water totaled over 2 million lbs. These releases were primarily from adhesives and sealants industries. The largest releases occurred in Texas. The largest direct releases to water occurred in Louisiana.

What happens to Styrene when it is released to the environment?

Styrene released to water rapidly evaporates and is degraded by microbes. It does not bind well to soils and may leach to groundwater, but its rapid break down minimizes this process. It does not tend to accumulate in aquatic life.

How will Styrene be Detected in and Removed from My Drinking Water?

The regulation for styrene became effective in 1992. Between 1993 and 1995, EPA required your water supplier to collect water samples every 3 months for one year and analyze them to find out if styrene is present above 0.5 ppb. If it is present above this level, the system must continue to monitor this contaminant.

If contaminant levels are found to be consistently above the MCL, your water supplier must take steps to reduce the amount of styrene so that it is consistently below that level. The following treatment methods have been approved by EPA for removing styrene: Granular activated charcoal in combination with Packed Tower Aeration.

How will I know if Styrene is in my drinking water?

If the levels of styrene exceed the MCL, 0.1 ppm, the system must notify the public via newspapers, radio, TV and other means. Additional actions, such as providing alternative drinking water supplies, may be required to prevent serious risks to public health.

Drinking Water Standards:

Mclg: 0.1 ppm

Mcl: 0.1 ppm

Styrene Releases to Water and Land, 1987 to 1993 (in pounds):

TOTALS (in pounds)275,8881,796,451

Top Ten States*

Major Industries*
Adhesives, sealants0537,360
Concrete products0398,424
Synthetic rubber152,215149,147
Misc. plastic products515201,713
Plastics and resins25,13371,363
Boatbuilding, repair22083,256
Car parts, access.079,250
Misc. Indust. organics34,27543,290
Travel trailers, campers045,129
Custom plastic resins72044,320

* Water/Land totals only include facilities with releases greater than a certain amount - usually 1000 to 10,000 lbs.

As part of the Drinking Water and Health pages, this fact sheet is part of a larger U.S. EPA publication:
EPA National Primary Drinking Water Regulations