Para-Dichlorobenzene at Memorial Academy
This page last reviewed October 21, 2010
Background
Atmospheric para-dichlorobenzene vaporizes directly into the air from its solid crystal form. The crystals are
white, volatile, and non-corrosive, with a penetrating odor. Through inhalation, ingestion, and dermal contact,
para-dichlorobenzene can irritate the skin, eyes, and respiratory tract. Long-term inhalation exposure may affect
the liver, skin, and central nervous system. California has determined under Assembly Bill 1807 and Proposition
65 that para-dichlorobenzene is a cancer-causing compound.
Para-dichlorobenzene is used as a room deodorant, a dye intermediate, and a registered insecticide. These sources
account for approximately 99% of statewide para-dichlorobenzene emissions. Since para-dichlorobenzene is used as
a room deodorizer and for moth control, volatilization from these products that are nearly pure para-dichlorobenzene
is the most significant indoor source. There are no identified natural sources of para-dichlorobenzene.
Based on the statewide annual average, ambient para-dichlorobenzene concentrations remained fairly constant during
the1990s.
Ambient Monitoring Results
Ambient levels of para-dichlorobenzene are routinely monitored at approximately twenty sites in the California
air toxics monitoring network. The statewide average concentration of para-dichlorobenzene during 1998-2000 was
0.1 ppb (parts per billion), with values ranging from 0.1 ppb to 1.9 ppb. Relative to the statewide average, the
San Diego region was 20% lower for the same time period.
The ambient monitoring results at Memorial Academy are provided here:
- A graph comparing the monthly summaries of para-dichlorobenzene at Memorial Academy with historical statewide and regional levels
- A table of summary statistics
- Raw data in Excel format
Cancer Risk
Cancer risk is the number of excess cancer cases among a million people if the people are exposed to levels of a toxic air pollutant over 70 years. Nine measured compounds, which do not include diesel particulate matter, make up most of the estimated cancer risk at Memorial Academy. Para-dichlorobenzene represents approximately 3% of the cancer risk of the nine measured compounds.
