1,3-Dichloropropane
1,3-Dichloropropane is an industrial solvent, and sometimes a leftover impurity in farm soil fumigants.
It is rarely found in tap water: national testing in the 1990s found it in fewer than 1 in 800 water systems, at low levels. No studies in people exist, and the one animal study showed liver and kidney changes only at doses far above anything in drinking water.
USGS health-based screening level, our line
100 ppb
There is no federal legal limit for 1,3-dichloropropane. It is rarely found in tap water, and no one has studied it in people.
1,3-Dichloropropane: what is it, and where does it come from?
1,3-Dichloropropane is a man-made chlorinated solvent, a small three-carbon molecule with two chlorine atoms that evaporates easily, part of the volatile organic compound (VOC) family. It is made mainly as a chemical building block, and it also turns up as an impurity in soil fumigants based on 1,3-dichloropropene, used against worms that attack crop roots.
It can reach groundwater from industrial releases, waste sites, or fields treated with those fumigants. It is rare: EPA's analysis of 1990s monitoring found it in 0.12 percent of about 17,000 public water systems in one round and 0.06 percent of about 24,000 in the next.
It has never been part of EPA's modern national surveys, so there is no newer national data, and EPA dropped it from its list of contaminants under consideration in 2009.
1,3-Dichloropropane: why does it matter?
Almost nothing is known about 1,3-dichloropropane's effects on people, because no one has studied it in people.
One 90-day rat study shows the liver and kidneys change first, but only at doses thousands of times higher than anything found in tap water. Lab tests for DNA damage are mixed: some human cells in a dish showed breaks, while the one test in live mice was negative.
There are no cancer studies at all, so no agency has rated its cancer risk, and the World Health Organization says there is not enough data to set a guideline. Our line, 100 ppb, is a USGS screening level built from EPA's 2006 provisional safe dose, which EPA rates low to medium confidence.
We treat industrial solvents as a family we would rather not see in drinking water at all: most were never meant to be there, a few are proven harmful, and for the rest, including this one, the absence of studies is not proof of safety.
EPA's 2001 analysis of 1990s monitoring found 1,3-dichloropropane above the reporting limit in 0.12 percent of 16,947 public water systems in Round 1 and 0.06 percent of 24,065 in Round 2, with 99th percentile values below 1 and 2 ppb.
EPA's 2006 review found one 90-day rat study, in which the liver and kidneys changed first, at doses far above drinking-water levels; there are no human, cancer or long-term animal studies.
US EPA, Provisional Peer Reviewed Toxicity Values for 1,3-Dichloropropane (CASRN 142-28-9), 2006
The World Health Organization says 1,3-dichloropropane is rarely found in water and that the data are not enough to set a guideline value.
1,3-Dichloropropane: what do we grade it against?
The table below lists each level that applies to 1,3-Dichloropropane, what it is based on and who set it, and says which ones are enforceable.
| Contaminant | Health-based level | Source (health-based) |
|---|---|---|
| 1,3-Dichloropropane (ppb) | 100 USGS health-based screening level, our line | USGS Health-Based Screening Levels, from US EPA PPRTV 2006 |
Health-based levels come from peer-reviewed research and government risk scientists working without cost constraints, while legal limits are enforceable compromises. Your report grades to the health column.
What helps against 1,3-Dichloropropane?
The approaches below are the ones people use for 1,3-Dichloropropane at home. Each entry says what it does and what it cannot do, and not every one helps.
Direct fixes
Activated carbon filtration
The same carbon filtration that handles the well-known industrial solvents handles this one too, so a reading is easy to remove.
Common questions about 1,3-Dichloropropane
If there is no proof it harms people, why have a line at all?
Because the absence of studies is not the same as proof of safety. Our line is the screening level USGS built from EPA's provisional safe dose, and we treat it like any industrial solvent: something worth removing when it shows up, and easy to remove with carbon filtration.
How does it get into water?
From industrial releases and waste sites, or from fields treated with soil fumigants that carry it as an impurity. It is rarely found in public water.
Sources cited for 1,3-Dichloropropane
Every number on this 1,3-Dichloropropane page traces to one of the 3 sources below: 2 government or regulatory.
Government & regulatory