Regulation and Risk Assessment of 1,4-Dioxane - Environmental Investigation and Remediation - page 279

TABLE 6.6
European PNECs Calculated for 1,4-Dioxane in the Aquatic Environment

Compartment or Organisms PNECs Indicator Species References

Microorganisms 2700 mg/L Pseudomonas putida Bringmann and Kühn

(1977b); BASF (1979)

Sediment compartment 43.3 mg/kg (wet weight) Calculated with EUSES ECB (2002)

Aquatic compartment
(algae, invertebrates, i sh)

57.5 mg/L Mycrocystis aeruginosa

(blue green algae)

Bringmann and Kühn (1976)

Terrestrial compartment 14 mg/kg (wet weight) Calculated with EUSES ECB (2002)

Source: European Chemicals Bureau (ECB), 2002, European Union risk assessment report: 1,4-Dioxane. Institute for
Health and Consumer Protection, European Union.
Note: EUSES is the European Union System for the Evaluation of Substances model.

6.2.3 T OXICITY OF 1,4-D IOXANE TO A QUATIC AND T ERRESTRIAL O RGANISMS
In soil, surface water, and sediment ecosystems, 1,4-dioxane is not persistent because of its low afi n-
ity for adsorption to organic carbon, which also causes a low potential for 1,4-dioxane to be biocon-
centrated in aquatic receptors. Wildlife can be exposed to 1,4-dioxane through ingestion, inhalation,
and dermal contact; however, 1,4-dioxane does not bioaccumulate in food chains (USEPA, 1999).
USEPA derived a 1,4-dioxane TRV for mammals from a 23-month chronic study of lung tumors
in guinea pigs to determine the Lowest Observed Adverse Effects Level (LOAEL; Hoch-Ligeti and
Argus, 1970, see Chapter 5). The LOAEL dose, 1070 mg/d, was converted to an equivalent dose
based on body weight and intake rate for the guinea pig. Applying a UF of 0.1, the mammalian
TRVis 107 mg/(kg d) (USEPA, 1999).
Exposures to terrestrial wildlife through the food chain are not signii cant with respect to the
l e v e l s o f 1, 4 - d i o x a n e t y p i c a l l y o b s e r v e d i n c o n t a m i n a t e d s o i l s ( H u n t l e y e t a l . , 2 0 0 4) . B i o c o n c e n t r a t i o n
factors were estimated for wild birds and rodents, including the American robin, canvas-back duck,
deer mouse, least shrew, mallard duck, marsh rice rat, marsh wren, mourning dove, muskrat, north-
ern bobwhite, salt-marsh harvest mouse, short-tailed shrew, western meadow lark, and white-footed
mouse. Estimated bioconcentration factors are on the order of 10 −9 -10 −8 ; therefore, bioconcentration
in these and in similar species is not of a signii cant concern (USEPA, 1999; U.S. Army, 2000). The
Ontario Ministry of the Environment estimated TRVs for several wildlife species by using a 1.0 mg/
(kg d) LOAEL for the rat, as tabulated in Table 6.11 (OMOE, 2007).

6.2.4 R EGULATING 1,4-D IOXANE D ISCHARGES FROM G ROUNDWATER C LEANUP S ITES
The discovery of 1,4-dioxane in efl uent from a groundwater treatment system designed to remove
chlorinated solvents can present a vexing dilemma to remedial project managers. As described in

TABLE 6.7
Long-Term Toxicity of 1,4-Dioxane to Aquatic Algae

Result
(mg/L) Species Limit Method References

Scenedesmus quadricauda
(green algae)

8-day cell multiplication
inhibition

5600 Static Bringmann and Kühn (1977b)

Microcystis aeruginosa
(cyanobacteria; blue-green algae)

8-day cell multiplication
inhibition

575 Static Bringmann and Kühn (1976)