Technical Factsheet on: ENDRIN
List of Contaminants
As part of the Drinking Water and Health pages, this fact sheet is part of a larger publication:
National Primary Drinking Water Regulations
Drinking Water Standards
MCLG: 0.002 mg/L
MCL: 0.002 mg/L
HAL(child): 1 - to 10-day: 0.02 mg/L; Longer term: 0.003 mg/L
Health Effects Summary
Acute: EPA has found endrin to potentially cause the following health effects from acute exposures at
levels above the MCL: tremors, labored breathing, mental confusion, convulsions.
Drinking water levels which are considered "safe" for short-term exposures: For a 10-kg (22 lb.) child
consuming 1 liter of water per day, upto a ten-day exposure to 0.02 mg/L or up to a 7-year exposure to
0.003 mg/L.
Chronic: Endrin has the potential to cause the following health effects from long-term exposures at levels
above the MCL: convulsions and damage to liver tissue.
Cancer: There is inadequate evidence to state whether or not endrin has the potential to cause cancer
from a lifetime exposure in drinking water.
Usage Patterns
Endrin is an aliphatic chlorinated insecticide which has been used mainly on field crops such as cotton,
maize, sugarcane, rice, cereals, ornamentals, and other crops. It has also been used for grasshoppers in
non-cropland and to control voles and mice in orchards.
Once widely used in the US, most uses were cancelled in 1980. Production in 1980 was reported to be
100,000 lbs.
Release Patterns
Endrin's former source in the environment is from use as an insect, bird and rat-killer. It has been used on
agricultural crops, cotton seeds, control of birds on buildings and mice in orchards. Its major use has
been on cotton crops. The U.S. EPA presently considers the pesticide cancelled.
Environmental Fate
Endrin is very persistent, but it is known to photodegrade to delta-ketoendrin (half-life 7 days - June).
Endrin released to soils will persist for extremely long periods of time (up to 14 yr or more).
Biodegradation may be enhanced somewhat in flooded soils or under anaerobic conditions. Its low water
solubility and strong adsorption to soil makes leaching into groundwater unlikely. However, the detection
of endrin in certain groundwater samples suggest that leaching may be possible in some soils. Endrin's
low vapor pressure suggests only limited evaporation from soil. However, several studies have suggested
that moderate to extensive loss of endrin from soils and crops was due to evaporation. Runoff from rain or
irrigation of particle-associated endrin will carry particle-associated endrin to water systems.

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Endrin released to water systems will not hydrolyze or biodegrade. It will be subject to photoisomerization
to ketoendrin. It will extensively sorb to sediment. Evaporation from water will not be significant.
Fate of endrin in the atmosphere is unknown, but it probably will be primarily associated with particulate
matter and be removed mainly by rainout and dry deposition.
There is significant bioconcentration of endrin in fish, with BCFs of 1335-10,000 reported. In addition,
there is moderate to extensive bioconcentration in shellfish (BCF of 500-1250) and in snails (BCF of
49,000).
Monitoring data demonstrates that endrin continues to be a contaminant in air, water, sediment, soil, fish,
and other aquatic organisms. Human exposure appears to come mostly from food or occupational
exposure.
Chemical/ Physical Properties
CAS Number: 72-20-8
Color/ Form/Odor: Odorless white crystals
M.P.: 200 C B.P.: decomp. 245 C
Vapor Pressure: 2x10-7 mm Hg at 25 C
Octanol/Water Partition (Kow): Log Kow = 5.6(calc.)
Density/Spec. Grav.: 1.7 at 20 C
Solubility: 0.2 mg/L of water; Slightly soluble in water
Soil sorption coefficient: Koc =34,000 (est); low mobility in soil
Odor/Taste Thresholds: N/A
Bioconcentration Factor: 1335 to 10,000 in fish; expected to bioconcentrate in aquatic organisms.
Henry's Law Coefficient: 4x10-7 atm-cu m/mole
Trade Names/Synonyms: Nendrin; EN 57; Endrex; Endricol; Hexadrin; Mendrin; Oktanex; Compound
269; Hexachloroepoxy- octahydro-endo,endo-dimethano- naphthalene
Other Regulatory Information
Monitoring For Ground/Surface Water Sources:
Initial Frequency- 4 quarterly samples every 3 years
Repeat Frequency- If no detections during initial round:
2 quarterly per year if serving >3300 persons;
1 sample per 3 years for smaller systems
Triggers - Return to Initial Freq. if detect at > 0.00001 mg/L
Analysis:

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Reference Source Method Numbers
EPA 600/4-88-039 505; 508; 508.1; 525.2
Treatment- Best Available Technologies:
Granular Activated Charcoal
For Additional Information:
EPA can provide further regulatory and other general information:
EPA Safe Drinking Water Hotline - 800/426-4791
Other sources of toxicological and environmental fate data include:
Toxic Substance Control Act Information Line - 202/554-1404
Toxics Release Inventory, National Library of Medicine - 301/496-6531
Agency for Toxic Substances and Disease Registry - 404/639-6000
National Pesticide Hotline - 800/858-7378

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