August, 1987
                                     DIELDRIN

                                 Health Advisory
                             Office of Drinking Water
                       U.S. Environmental Protection Agency
DRAFT
I. INTRODUCTION
        The  Health Advisory (HA) Program,  sponsored by the Office.of Drinking
   Water (ODW), provides information on the health effects, analytical method-
   ology and treatment technology that would be useful in dealing with the
   contamination  of drinking water.  Health Advisories describe nonregulatory
   concentrations of drinking water contaminants at which adverse health effects
   would not be anticipated to occur over specific exposure durations.  Health
   Advisories contain a margin of safety to protect sensitive members of the
   population.

        Health Advisories serve as informal technical guidance to assist Federal,
   State and local officials responsible for protecting public health when
   emergency spills or contamination situations occur.  They are not to be
   construed as legally enforceable Federal standards.  The HAs are subject to
   change as new  information becomes available.

        Health Advisories are developed for one-day, ten-day, longer-term x
   (approximately 7 years, or 10% of an individual's lifetime) and lifetime
   exposures based on data describing noncarcinogenic end points of toxicity.
   Health Advisories do not quantitatively incorporate any potential carcinogenic
   risk from such exposure.  For those substances that are known or probable
   human carcinogens, according to the Agency classification scheme (Group A or
   B),  Lifetime HAs are not recommended.  The chemical concentration values for
   Group A or B carcinogens are correlated with carcinogenic risk estimates by
   employing a cancer potency (unit risk)  value together with assumptions for
   lifetime  exposure and the consumption of drinking water.  The cancer unit
   risk is usually derived from the linear multistage model with 95% upper
   confidence.limits.  This provides a low-dose estimate of cancer risk to
   humans that is considered unlikely to pose a carcinogenic risk in excess
   of  the stated  values.  Excess cancer risk estimates may also be calculated
   using the One-hit, Weibull, Logit or Probit models.  There is no current
   understanding  of the biological mechanisms involved in cancer to suggest that
   any one of these models is able to predict risk more accurately than another.
   Because each model is based on differing assumptions, the estimates that are
   derived car differ by several orders of magnitude.

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    Dieldrin
                                         -2-
                  August, 1987
II. GENERAL INFORMATION AND PROPERTIES

    CAS No.  60-57-1

    Structural Formula
                                                 Cl
                                                       Cl
           Dieldrin; 3,4,5,6,9,9-hexachloro-1a,2,2a, 3,6,6a,7,7a-octahydro-
           2, 7: 3,6-dimethanonaphth[2,3-b]oxirene (Windholz, 1983).
    Synonyms
            HEOD; Alvit; Quintox; Octalox (IPCS, 1987).
    Uses
         0  Formerly used for control of soil insects, public health insects,
            termites and many other pests.  These uses have been cancelled and
            manufacture discontinued in the United States (Meister, 1983).

    Properties  (MAS, 1977; Weast and Astle, 1982; Windholz, 1983)
            Chemical Formula
            Molecular Weight
            Physical State
            Boiling Point
            Melting Point
            Density
            Vapor pressure (20°C)
            Water Solubility  (25°C)
            Log Octanol/water Partition
              Coefficient
            Taste Threshold
            Odor Threshold (water)
            Conversion Factor
C12H8C160
380.93
Crystals

175 to 176°C
*>•>
3.1 x 10~6 mm Hg
0.25 mg/L
0.04 mg/L
    Occurrence
            Dieldrin has been found in 9,809 of 52,453 surface water samples
            analyzed and in 217 of 6,042 ground water samples (STORET, 1987).
            Samples were collected at 8,831 surface water locations and 4,522
            ground water locations, and Dieldrin was found in 48 states, Canada
            and Puerto Rico.  The 85th percentile of all nonzero samples was
            0.01 ug/L in surface water and 0.10 ug/L in ground water sources.
            The maximum concentration found was 301 ug/L in surface water and in
            10.08 ug/L in ground water.

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     Dieldrin                                                  August, 1987

                                       '   -3-


     Environmental Fate

          0  Dieldrin  is  stable and  highly persistent in the environment.

          0  Dieldrin  has the longest half-life of the chlorinated hydrocarbons in
             water 1-m deep (half-life -  723 days) (MacKay and Wolkoff, 1973).


III. PHARMACOKINETICS

     Absorption

          0  A single  oral dose of dieldrin at 10 rag/kg body Weight (bw) administered
             in corn oil  to male Sprague-Dawley rats produced consistent concentrations
             of dieldrin  in plasma,  muscle, brain, kidney and liver for periods up
             to 48 hours  suggesting  slow  absorption of the substance (Hayes, 1974).

     Distribution

          0  Rats given a single oral dose of dieldrin at 10 mg/kg showed concen-
             trations  of  dieldrin  in fat, muscle, liver, blood, brain and kidney.
             The highest  concentration of dieldrin was in fat.  The lowest con-
             centration was in the kidney (Hayes, 1974).

     Metabolism

          0  Both the  CFE rat and  CF1 mouse, following a single oral dose of
             dieldrin  (not less than 85%  HEOD) at 3 and 10 mg/kg in olive oil,
             respectively, metabolized dieldrin to 9-hydroxydieldrin, 6,7^trans-
             dihydroaldrindiol and some unidentified metabolites.  The rat, but
             not the mouse, also metabolized dieldrin to pentachloroketone (Baldwin
             and Robinson, 1972).

     Excretion

          0  Female rats  infused with total doses of 8 to 16 mg 36ci-dieldrin/kg bw
             excreted  approximately  70% of the infused dose in the feces over a
             period of 42 days, while only about 10% of the dose was recovered in
             the urine.  Excretion was markedly increased by restriction of the
             diet indicating that  the1 concentration of dieldrin in the blood
             increased as fat was  mobilized (Heath and Vandekar, 1964).


 IV. HEALTH EFFECTS
     Humans
             Dieldrin has been reported to cause hypersensitivity and muscular
             fasciculations that may be followed by convulsive seizures and
             respective changes in the EEC pattern.  Acute symptoms of intoxication
             include hyperirritability, convulsions and/or coma sometimes accompanied
             by nausea, vomiting and headache, while chronic intoxication may result
             in fainting, muscle spasms, tremors and loss of weight.  The lethal
             dose for humans is estimated to be about 5 g (ACGIH, 1984).

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Dieldrin                                                  August, 1987
Animals
   Short-term Exposure

     0  RTECS (1985) reported the acute oral LDs0 values of dieldrin in the
        rat, mouse, dog, monkey, rabbit, pig, guinea pig and hamster as 38.3,
        38, 65, 3, 45, 38, 49 and 60 mg/kg, respectively.

   Dermal/Ocular Effects

     0  Aldrin or Dieldrin (dry powder) applied to rabbit skin for 2 h/day,
        5 days/week had no discernible effects (IPCS, 1987).

   Long-term Exposure

     0  Groups of Osborne-Mendel rats, 1 2/sex/level, were fed 0,  0.5, 2, 10,
        50, 100 or 150 ppm dieldrin (recrystallized, 100% active ingredient)
        in their diet for 2 years.  These doses correspond to approximately
        0, 0.025, 0.1, 0.5, 2.5, 5.0 or 7.5 mg/kg/day, respectively (Lehman,
        1959).  Survival was markedly decreased at levels of 50 ppm and
        above.  Liver-to-body weight ratios were significantly increased at
        all treatment levels, with females showing the effect at 0.5 ppm and
        males at 10 ppm and greater.  Microscopic lesions were described as
        being characteristic of chlorinated hydrocarbon exposure.  These
        changes were minimal at the 0.5 ppm level.  Male rats, at the two
        highest dose levels (100 and 150 ppm), developed hemorrhagic and/or
        distended urinary bladders usually associated with considerable
        nephritis (Fitzhugh et al., 1964).  A Lowest-Observed-Adverse-Effect-
        Level (LOAEL) of 0.025 mg/kg/day, the lowest dose tested, was identified
        in this study.

     0  Dogs, one/sex/dose level (two/sex at 0.5 mg/kg/day), fed dieldrin
        (recrystallized, 100% active ingredient) at 0.2 to 10 mg/kg/day,
        6 days/week for up to 25 months, showed toxic effects including weight
        loss and convulsions at dosages of 0.5 mg/kg/day or more.  Survival was
        inversely proportional to dose level.  No toxic effects, gross or
        microscopic, were seen at a dose level of 0.2 mg/kg/day  (Fitzhugh et
        al., 1964).

     0  Groups of Carworth Farm "E" strain rats, 2 5/ sex/dose level, were fed
        dieldrin  (>99% purity) in the diet at 0.0, 0.1, 1.0 or 10.0 ppm for
        2 years.  These doses correspond to approximately 0, 0.005, 0.05 or
        0.5 mg/kg/day, respectively (Lehman, 1959).  At 7 months, the 1-ppm
        intake level was equivalent to approximately 0.05 and 0.06 mg/kg/day
        for males and females, respectively.  No effects on mortality, body
        weight, food intake, hematology and blood or urine chemistries were
        seen.  At the 10-ppm level, all animals became irritable after 8 to
        13 weeks of treatment and developed tremors and occasional convulsions.
        Liver weight and liver-to-body weight ratios were significantly
        increased in females receiving both 1.0 and 10 ppm.  Pathological
        findings described as organochlorine-insecticide changes of the liver
        were found in one male and six females at the 10-ppm level.  No
        evidence of tumor igenesis was found (Walker et al., 1969).

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Dieldrin                                                    August, 1987

                                     -5-
     0  Groups of beagle dogs (five/sex/dose)  were treated daily by capsule
        with dieldrin (>99% purity)  at 0.0,  0.005 or 0.05 rag/kg in olive oil
        for 2 years.   No treatment-related effects were seen in general
        health,  behavior,  body weight or urine chemistry.  A significant
        increase in plasma alkaline  phosphate  in both sexes and a significant
        decrease in serum protein concentration in males receiving the high
        dose were not associated  with any clinical or pathological change.
        Liver weight  and liver-to-body weight  ratios were significantly
        increased in  females receiving the high dose, 0.05 mg/kg/day, but no
        gross or microscopic lesions were found.  There was no evidence of
        tumorigenic activity (Walker et al.,  1969).

     0  Dieldrin (>99% pure) was  administered  to CF1 mice of both sexes in
        the diet for  128 weeks.  Dosages were 1.25, 2.5, 5, 10 or 20 ppm
        dieldrin.  These doses are equivalent to 0.19, 0.38, 0.75, 1.5 or 3
        mg/kg body weight (Lehman, 1959).  At  the 20-ppm dose level,-approximately
        25% of the males and nearly  50% of the females died during the first
        3 months of the experiment.   Palpable intra-abdominal masses were
        detected after 40, 75 or  100 weeks in  the 10, 5 and 2.5-ppm-treated
        groups,  respectively.  At 1.25 ppm,  liver enlargement was not palpable
        and morbidity was similar to that of controls.  A No-Observed-Adverse-
        Effect-Level  (NOAEL) cannot  be established because clinical chemistry
        parameters were not determined (Walker et al., 1972).

   Reproductive Effects

     0  Coulston et al. (1980) studied the reproductive effects of dieldrin
        in Long Evans rats.  Pregnant rats were administered 0 or 4 mg/kg bw
        dieldrin by gavage daily  from day 15 of gestation through 21 days
        postpartum.  The treated  group did not differ from the control group
        when examined for fecundity, number of stillbirths, perinatal mortality
        and total litter weights.

   Developmental Effects

     0  Pregnant Syrian golden hamsters given. 30 mg/kg bw dieldrin (_>99% pure)
        in corn oil on days 7, 8  or  9 of gestation manifested an embryo-
        cidal and teratogenic response as evidenced by a statistically
        significant increase in fetal deaths,  a decrease in live fetal weight
        and an increased incidence of webbed foot, cleft palate and open eye
        (Ottolenghi et al., 1974).  Similar anomalies were observed in
        CD^i mice administered 15  mg/kg bw dieldrin on day 9 of gestation, but
        no effect was seen on fetal  survival or weight.

     0  Dieldrin (87% pure) was not  found to be teratogenic in the CD rats and
        CD-1 mice administered doses of 1.5,  3.0 or 6.0 mg/kg/day by gastric
        intubation on days 7 through 16 of gestation.  Fetal toxicity, as
        indicated by  a significant decrease in numbers of caudal ossification
        centers  at the 6.0-mg/kg/day dose level and a significant increase
        in the number of supernumerary ribs in one study group at both the
        3.0- and 6.0-mg/kg/day dose  level,  was reported in the experiments  in
        mice.  Maternal toxicity  in  the high-dose rats was.indicated by a 41%
        mortality and a significant  decrease in weight gain;  similarly, mice

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   Dieldrin                                                    August,  1987
           receiving 6.0 rag/kg/day showed a significant decrease in maternal
           weight gain.  A significant increase in liver-to-body weight
           ratio in one group of maternal mice was reported  at both 3.0 and 6.0
           mg/k9/day (Chernoff et al., 1975).

      Mutaqenicity

        0  Dieldrin was not mutagenic in the Salmonella/microsome test with and
           without S-9 mix (McCann et al., 1975).

        0  Dieldrin significantly decreased the mitotic index and increased
           chromosome abnormalities in STS mice bone marrow  cells in an in vivo
           study.  Similar observations were made  in human WI-38 embryonic lung
           cells in an in vitro test that also gave evidence of cytotoxicity,  as
           indicated by degree of cell degeneration (Majumdar et al., 1976).

      Carcinogenieity

        8  A dose-related increase in the incidence of hepatocellular carcinomas
           was observed in B6C3Fj mice, with the incidence in the high-dose
           males being significantly higher when compared to pooled controls
           (NCI, 1978).  Mice were given dieldrin (technical grade, >85% purity)
           in the diet at concentrations of 2.5 or 5 ppm for 80 weeks.  These
           doses correspond to approximately 0.375 or 0.75 mg/kg/day, respectively
           (Lehman, 1959).

        0  Osborne-Mendel rats treated with dieldrin at Time-Weighted Average  (TWAf
           doses of 29 or 65 ppm in the diet (approximately  1.45 or 3.25 mg/kg/day,
           respectively, based on Lehman, 1959) for 80 weeks, did not elicit
           treatment-related tumors (NCI, 1978).

        •  Diets containing 0.1, 1.0 or 10 ppm dieldrin (>99% purity), when
           given to mice of both sexes for 132 weeks, were associated with an
           increased incidence of liver tumors at all dose levels tested (Walker
           et al., 1972).  These doses are equivalent to approximately 0.015,
           0.15 or 1.5 mg/kg/day, respectively (Lehman, 1959).


V. QUANTIFICATION OF TOXICOLOGICAL EFFECTS

        Health Advisories (HAs) are generally  determined for one-day, ten-day,
   longer-term (approximately 7 years) and lifetime exposures if adequate data
   are available that identify a sensitive noncarcinogenic end point of toxicity.
   The HAs for noncarcinogenic toxicants are derived using the following formula:

                 HA - (NOAEL or LOAEL) x (BW)  = __   /L (	   /L)
                        (UF) x (    L/day)
   where:
           NOAEL or LOAEL = No- or Lowest-Observed-Adverse-Effect-Level
                            in mg/kg bw/day.

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Dieldrin                                                  August, 1987

                                     -7-
                    BW - assumed body weight of a child (10-kg) or
                         an adult (70 kg).

                    UF « uncertainty factor (10, 100 or 1,000), in
                         accordance with NAS/ODW guidelines.

             	 L/day » assumed daily water consumption of a child
                         (1 L/day)  or an adult (2 L/day).

One-day Health Advisory

     No data were found in the available literature that was suitable for
determination of a One-day HA value for dieldrin.  It is, therefore, recommended
that the modified DWEL for a 10-kg  child (0.0005 mg/L, calculated below) be
used as a conservative estimate for the One-day HA value.

Ten-day Health Advisory

     No data were found in the available literature that was suitable for
determination of a Ten-day HA value for dieldrin.  It is, therefore, recommended
that the modified DWEL for a 10-kg  child (0.0005 mg/L, calculated below) be
used as a conservative estimate for the Ten-day HA value.

Longer-term Health Advisory
                                                              \
     No data were found in the available literature that was suitable for
determination of a Longer-term HA value for dieldrin.  It is, therefore,
recommended that the modified DWEL  for a 10-kg child (0.0005 mg/L,
calculated below) be used as a conservative estimate for the Longer-term HA
value.

Lifetime Health Advisory

     The Lifetime HA represents that portion of an individual's total exposure
that is attributed to drinking water and is considered protective of noncar-
cinogenic adverse health effects over a lifetime exposure.  The Lifetime HA
is derived in a three step process.  Step 1 determines the Reference Dose
(RfD), formerly called the Acceptable Daily Intake (ADI).  The RfD is an esti-
mate of a daily exposure to the human population that is likely to be without
appreciable risk of deleterious effects over a lifetime, and is derived from
the NOAEL (or LOAEL), identified from a chronic (or subchronic) study, divided
by an uncertainty factor(s).  From  the RfD, a Drinking Water Equivalent Level
(DWEL) can be determined (Step 2).   A DWEL is a medium-specific (i.e., drinking
water) lifetime exposure level, assuming 100% exposure from that medium, at
which adverse, noncarcinogenic health effects would not be expected to occur.
The DWEL is derived from the multiplication of the RfD by the assumed body
weight of an adult and divided by the assumed daily water consumption of an
adult.  The Lifetime HA is determined in Step 3 by factoring in other sources
of exposure, the relative source contribution (RSC).  The RSC from drinking
water is based on actual exposure data or, if data are not available, a
value of 20% is assumed for synthetic organic chemicals and a value of 10%
is assumed for inorganic chemicals.  If the contaminant is classified as a
Group A or B carcinogen, according  to the Agency's classification scheme of

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Dieldrin
                                                          August, 1987
                                     -8-
carcinogenic potential (U.S. EPA, 1986), then caution should be exercised in
assessing the risks associated with lifetime exposure to this chemical.

     The study of Walker et al. (1969), in which rats were fed dieldrin in
the diet at 0.0, 0.1, 1 or 1 0 ppm for 2 years (approximately 0, 0.005, 0.05
or -0.5 mg/kg/day based on Lehman, 1959), has been selected as the basis for
calculating the DWEL.  In this study, liver weight and liver-to-body weight
ratios were significantly increased in females receiving 1 and 10 ppm, while
pathological changes consistent with exposure to organochlorides were evident
at the 10-ppm level.  This study established a NOAEL of 0.1 ppm (equivalent
to 0.005 mg/kg/day).

     Using a NOAEL of 0.005 mg/kg/day, the Lifetime HA is calculated as
follows:
Step 1:  Determination of the Reference Dose (RfD)

                  RFD •  .               = 0.00005 mg/kg/day
                        0.005 mg/kg/day
                              100
where:
        0.005 mg/kg/day » NOAEL, based on the absence of hepatic effects in
                          rats fed dieldrin in the d^et.

                    1 00 = uncertainty factor, chosen in accordance with NAS/ODW
                          guidelines for use with a NOAEL from an animal study.
Step 2:  Determination of the Drinking Water Equivalent (DWEL)

        DWEL =   .                         a 0. 001 75 mg/L (1.75 ug/L)
               (0.00005 mg/kg/day) (70 kg)
                         2 L/day
where:
         0.00005 mg/kg/day = RfD.

                     70 kg « assumed body weight of an adult.

                   2 L/day = assumed daily water consumption of an adult.

Step 3:  Determination of the Lifetime Health Advisory

     Dieldrin may be classified in Group B2:  probable human carcinogen.  A
Lifetime HA is not recommended for dieldrin.

     The estimated excess cancer risk associated with lifetime exposure to
drinking water containing dieldrin at 1.75 ug/L is approximately 8.05 x 10-4.
This estimate represents the .upper 95% confidence limit from extrapolations
prepared by EPA's Carcinogen Assessment Group (U.S. EPA, 1987) using the
linearized multistage model.  The actual risk is unlikely to exceed this
value, but there is considerable uncertainty as to the accuracy of risks
calculated by this methodology.

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    Dieldrin                                                  August,  1987
    Evaluation of Carcinogenic  Potential

         4  Applying the criteria described  in EPA's proposed guidelines for
            assessment of carcinogenic  risk.  (U.S.  EPA,  1986), dieldrin may be
            classified in Group B2:  probable human carcinogen.

         0  Evidence has been presented in several carcinogenicity studies showing
            that dieldrin is carcinogenic to mice.  Thirteen data sets from these
            studies are adequate for quantitative  risk  estimation.  Utilizing the
            linearized multistage model, the U.S.  EPA performed  potency estimates
            for each of these data sets.  The geometric mean of  the potency
            estimates, Q1 * = 16 (mg/kg/day)~1,  was estimated as  the potency for the
            general population  (U.S. EPA, 1987).

         0  Using this Qi* value and assuming that a 70-kg  human adult consumes
            2 liters of water a day over a 70-year lifespan,  the linearized
            multistage model estimates  that  concentrations  of 0.219,  0.0219 and
            0.00219 ug dieldrin per liter may result in excess cancer risk of
            10-4, 10-5 and 10~6, respectively.

         0  The linearized multistage model  is only one method of estimating
            carcinogenic risk.   From the data contained in  U.S.  EPA (1987), it
            was determined that five of the  thirteen data sets were suitable for
            determining slope estimates for  the probit, logit, Weibull and gamma-
            multihit models.  Using the geometric  mean  of these  slope estimates
            (13 for multistage,  5 for other  models) at  their upper 95% confidence
            limits, the following comparisons of unit risk  (i.e.,  a 70-kg man
            consuming 2 liters  of water per  day containing  1  ug/L of  dieldrin over
            a lifetime) can be  made:  multistage,  4.78  x 10-4. probit, 7.7 x 10"12;
            logit, 5.09 x 10~6;  Weibull, 1.13 x 10-4; multihit,  5.68  x 10-4.  Each
            model is based on different assumptions. No current understanding of
            the biological mechanisms of carcinogenesis is  able  to predict which
            of these models is  more accurate than  another.

         0  While recognized as statistically alternative approaches, the range
            of risks described  by using any  of these modelling approaches has
            little biological significance unless  data  can  be used to support
            the selection of one model  over  another.  In the interest of consistency
            of approach and in  providing an  upper  bound on  the potential cancer
            risk, the Agency has recommended use of the linearized multistage
            approach.

         0  IARC (1982) concluded that  there is limited evidence that dieldrin is
            carcinogenic in laboratory  animals.


VI. OTHER CRITERIA, GUIDANCE AND STANDARDS

         0  ACGIH (1984) has established a short-term exposure limit  (STEL) of
            0.75 mg/m3 and an 8-hour Threshold Limit Value  (TLV)-TWA  exposure
            0.25 mg/m3 for dieldrin.

         0  U.S. EPA (1980) has  recommended  ambient water quality criteria of
            0.71 ng/L for dieldrin.  it is based on a carcinogenic potency factor

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      Dieldrin                                                  August, 1987

                                           -10-


              (q. *) of 30.37 (ngA9/day)~1 derived from the incidence of hepato-
              cellular carcinoma in a mouse feeding study conducted by Walker et
              al. (1972).

           0  Residue tolerances ranging from 0.02 to 0.1 ppm have been established
              for dieldrin in or on agricultural commodities (U.S. EPA, 1985).

           0  WHO (1982) established guidance of 0.03 ug dieldrin/L in drinking water.


 VII. ANALYTICAL METHODS

           0  Determination of dieldrin is by a liquid-liquid extraction gas
              chromatographic (GC) procedure (U.S. EPA, 1984a).  In this procedure,
              a 1-liter sample is extracted with methylene chloride using a separatory
              funnel.  The methylene chloride extract is dried and exchanged to
              hexane during concentration to a volume of 10 mL or less.  The extract
              is separated by GC, and the components are then measured with an
              electron-capture detector.  Identification may be corroborated through
              the use of two unlike columns or by gas chromatography-mass
              spectroscopy (GC-MS).  A GC-MS procedure is available (U.S. EPA,
              1984b) that allows for the qualitative and quantitative confirmation
              of results obtained by the GC procedure.


VIII. TREATMENT TECHNOLOGIES

           0  Available data indicate that reverse osmosis (RO), granular-activated
              carbon (GAC) adsorption, ozonation and conventional treatment will
              remove dieldrin from water.  The percent removal efficiency ranges
              from 50 to 99+%.

           0  Laboratory studies indicate that RO is a promising treatment method
              for dieldrin-contaminated waters.  Chian et al. (1975) reported 99+%
              removal efficiency for two types of membranes operating at 600 psig and
              a flux rate of 8 to 12 gal/ft2/day»  Membrane adsorption, however, is
              a major concern and must be considered, since breakthrough of dieldrin
              would probably occur once the adsorption potential of the membrane
              was exhausted.

           0  GAC is effective for dieldrin removal.  Pirbazari and Weber (1983)
              reported 99+% dieldrin removal efficiency of a GAC column operating
              at an empty bed contact time (EBCT) of 15 minutes and a hydraulic
              loading of 1.4 gal/ft2/minf for the entire test period (approximately
              7.5 months).

           0  Pirbazari and Weber (1983) determined adsorption isotherms using GAC
              on dieldrin in water solutions.  Resin adsorption was also found to
              remove dieldrin from water.  The Preundlich values determined by
              The authors indicate that the tested resins are not quite as effective
              as GAC in the removal of dieldrin from water.

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Dieldrin                                                    August,  1987

                                     -11-
        Ozonation treatment appears  to be  an  effective dieldrin removal
        method.   Treatment with  36 mg/L ozone (03)  removed  50% of  dieldrin
        while 11  mg/L 03  removed only 15%  of  dieldrin (Robeck  et al.,  1965).

        Conventional water-treatment techniques  using alum  coagulation,
        sedimentation and filtration proved to be 55% effective in removing
        dieldrin  from contaminated potable water supplies  (Robeck  et al.,
        1965).  Lime- and soda-ash softening  with ferric chloride  as a coagulant
        did  not improve upon the removal efficiency achieved with  alum alone.

        Oxidation with chlorine  and  potassium permanganate  is  ineffective in
        degrading dieldrin (Robeck et al., 1965).

        Treatment technologies for the removal of dieldrin  from water are
        available and have been  reported to be effective.   However,  selection
        of individual or  combinations of technologies to attempt dieldrin
        removal from water must  be based on a case-by-case  technical evaluation,
        and an assessment of the economics involved.

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    Dieldrin                                                    August, 1987

                           --            -12-"


IX. REFERENCES

    ACGIH.  1984.  American Conference of Governmental Industrial Hygienists.
         Documentation of the threshold limit values for substances in workroom
         air.  3rd ed.  Cincinnati, OH:  ACGIH.   p. 139.

    Baldwin, M.K. and J. Robinson.  1972.  A comparison of the metabolism of
         HEOD (Dieldrin) in CF1 mouse with that in the CFE rat.  Food Cosinet.
         Toxicol.  10:333-351.

    Chernoff, N., R.J. Kavlock, J.R. Kathrein,  J.M. Dunn and J.K. Haseman.
         1975.  Prenatal effects of dieldrin and photodieldrin in mice and rats.
         Toxicol. Appl. Pharmacol.  31:302-308.

    Chian, E.S., W.N. Bruce and H.H.P. Fang.  1975.  Removal of pesticides by
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