This is a fact sheet about a chemical that may be found in some public or
private drinking water supplies. It may cause health problems if found
in amounts greater than the health standard set by the United States
Environmental Protection Agency (EPA).
What is Para-dichlorobenzene and how is it used?
Para-dichlorobenzene (p-DCB) is an organic solid of white crystals with a
mothball-like odor. It is used mainly as an insecticidal fumigant
against clothes moths and as a deodorant for garbage and restrooms. It
is also used as an insecticide and fungicide on crops, and in the
manufacture of other organic chemicals and in plastics, dyes,
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:
Why is Para-dichlorobenzene 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
The MCLG for p-DCB has been set at 75 parts per billion (ppb)
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 75 ppb 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 p-DCB to potentially cause the following health
effects when people are exposed to it at levels above the MCL for
relatively short periods of time: nausea, vomiting, headaches, and
irritation of the eyes and respiratory tract.
has the potential to cause the following effects from a lifetime
exposure at levels above the MCL: anemia, skin lesions, appetite loss,
damage to liver and changes in blood.
How much Para-dichlorobenzene is produced and released to the
74 million lbs. of p-DCB were consumed by industry in 1986, and demand was
predicted to increase. Chemical waste dump leachates and direct
manufacturing effluents are reported to be the major source of p-DCB
pollution in Lake Ontario.
From 1987 to 1993, according to the Toxic Release Inventory, p-DCB
releases to water totalled almost 34,000 lbs. Releases to land totalled
nearly 4,500 lbs. These releases were primarily from a single chemical
manufacturing plant in West Virginia.
What happens to Para-dichlorobenzene when it is released to the
p-DCB only moderately binds to soil so it may leach to ground water.
Otherwise, it will evaporate and be slowly broken down by microbes. If
released to water, it will largely evaporate. p-DCB is not likely to
accumulate in most aquatic life, though it may in some fishes.
How will Para-dichlorobenzene be detected in and removed from my
The regulation for p-DCB became effective in 1989. 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 p-DCB 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 p-DCB so that it is consistently below that level.
The following treatment methods have been approved by EPA for removing
p-DCB: Granular activated charcoal in combination with Packed Tower
How will I know if Para-dichlorobenzene is in my drinking water?
If the levels of p-DCB exceed the MCL, 75 ppb, 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.
This is a factsheet about a chemical that may be found in some
public or private drinking water supplies. It may cause health problems
if found in amounts greater than the health standard set by the United
States Environmental Protection Agency (EPA).
Drinking Water Standards:
|Mclg: 75 ppb (parts per billion)
Para-dichlorobenzene Releases to Water and Land, 1987 to 1993 (in
TOTALS (in pounds)||
Top Five States*|
Industrial org. chem.
Cyclic crudes, intermed.
* Water/Land totals only include facilities with releases greater
than a certain amount - usually 1000 to 10,000 lbs.
Note: This fact sheet is part of a larger publication
adapted from U.S. EPA publication: EPA National Primary Drinking Water