Entry to the marine environment

Recorded levels in the marine environment

Fate and behaviour in the marine environment

Effects on the marine environment


Potential effects on interest features of European marine sites

Entry into the marine environment

Trifluralin is applied as a herbicide for pre-emergent control of annual grasses and some broad leaved weeds in a wide variety of vegetables and some fruit. It is usually directly incorporated into soils, although some trifluralin mixtures may be sprayed.

Trifluralin may enter the aquatic environment predominantly via diffuse sources resulting from its recommended use, e.g. in agricultural run-off bound mainly to soil particles. Industrial discharges, accidental spillages during transport, storage and use are potential point sources of trifluralin contamination.

Recorded levels in the marine environment

Monitoring data from the National Rivers Authority and the National Monitoring Programme Survey of the Quality of UK Coastal Waters are presented in Appendix D. No water column concentration was found to exceed the EQS value (see Appendix D). Monitoring data were not available for sediments or biota.

The available data suggest that concentrations of trifluralin in UK coastal and estuarine waters do not exceed relevant quality standards derived for the protection of saltwater life.

Fate and behaviour in the marine environment

Jones (1996) reviewed the fate and behaviour and aquatic toxicity of trifluralin. Trifluralin is readily adsorbed on solid surfaces. The solubility and log Kow are also expected to be pH dependent. A realistic value for solubility is likely to be below 1 mg l-1 and for log Kow greater than 4. The low vapour pressure indicates that loss from the water phase by volatilisation will be slow.

Kearney et al (1977) studied the degradation of trifluralin in model aquatic ecosystems containing a variety of organic matter. The addition of 100 g loam containing 1 µg g-1 of labelled trifluralin to a 4 litre aquarium filled with water resulted in a maximum water concentration after 30 days of 7.5 µg l-1 based on 14C measurement. After 33 days, only degradation products were isolated from the water and no trifluralin was detected in fish placed in the tank for the last 3 days of the test. As the experiment was carried out in daylight, photolysis was probably the major degradation process.

In the environment, biodegradation is not thought to be an important pathway for the removal of trifluralin from water or soils (Shuker and Hutton 1986). Photodecomposition is the major degradation process for trifluralin released into the aquatic environment (Helling 1976). Kosinski (1984) added trifluralin to artificial streams and calculated a half-life of less than one hour. The rapid loss of chemical was attributed to photodecomposition.

However, trifluralin present in the aquatic environment is likely to be readily degraded by photolysis and adsorbed onto sediments.

Effects on the marine environment

Toxicity to marine organisms

An exhaustive literature review on the toxicity of trifluralin to marine organisms has not been carried out for the purposes of this profile. The information provided in this section is taken from existing review documents (Jones 1996). The most sensitive groups of organisms have been identified.

Jones (1996) reviewed the aquatic toxicity of trifluralin. Data for marine organisms were found to be limited. Jones (1996) concluded that elevated trifluralin concentrations in the marine environment were likely to occur only in estuaries receiving significant freshwater inputs contaminated with run-off from agricultural land. Most of the trifluralin entering marine waters is therefore likely to be adsorbed on suspended solids and may therefore not be readily bioavailable. Invertebrates and fish were found to exhibit the greatest sensitivity.


Walsh (1972) reported that 2.5 mg l-1 of trifluralin reduced the growth of four marine phytoplankton species by 50%. No other data were found for marine algae.


Liu and Lee (1975) exposed adults and larvae of the mussel Mytilus edulis to trifluralin. Larval growth was inhibited at 90 µg l-1 and 100 µg l-1 affected the ability of adults to attach to glass. The corresponding LC50 for adults was 240 µg l-1.

The effects of a technical mixture of trifluralin (93% active ingredient) on eggs, larvae, juveniles and adults of Cancer magister (Dungeness crab) were investigated by Caldwell et al (1979). Exposure to 590 &micro;g l-1 for 24 hours in static water did not affect egg hatching success or first stage zoeal motility. In a further long-term continuous flow test with larvae, juveniles and adults 220 &micro;g l-1 produced 100% mortality of zoea after 8 days, whereas exposure to 26 &micro;g l-1 for 50 days produced no significant effects on survival but significantly delayed the first molt. The survival of juveniles exposed for 80 days to 590 &micro;g l-1 and of adults exposed to 300 &micro;g l-1 for 85 days was not affected. Based on the results for the larval stages the MATC for the crab was estimated to be 326 and <220 &micro;g l-1.


Trifluralin was found to be very toxic to sheepshead minnows Cyprinodon variegatus (Couch et al 1979). Exposure to 5.5-31 &micro;g l-1 for the initial 28 days of life resulted in acute vertebral dysplasia which was thought to be a direct result of the effect of trifluralin on the hormonal control of calcium metabolism. High calcium levels were found in the blood serum of adult sheepshead minnows exposed to 16.6 &micro;g l-1. Wells and Cowan (1982) also reported spinal deformities in minnows exposed to 16 &micro;g l-1 for 51 days.

Parrish et al (1978) studied sheepshead minnows exposed to trifluralin over a full life cycle (166 days). Exposure to 17.7 &micro;g l-1 caused significant mortality of adult fish, whereas 9.6 and 4.8 &micro;g resulted in significantly reduced growth and fecundity of adult fish, respectively. In addition, significantly reduced hatching success of embryos spawned by parent fish and survival and growth of the second generation fish were observed on exposure to 9.6 &micro;g l-1. From the results, an MATC of >1.3 and <4.8 &micro;g l-1 was estimated for the sheepshead minnow.

Sediment-dwelling organisms

Trifluralin is likely to be absorbed to sediment but no data could be located on the toxic effects to sediment-dwelling organisms.


No data on the bioaccumulation of trifluralin in marine organisms could be located. However, it has been demonstrated by Garnas (1976) that marine invertebrates metabolise trifluralin via oxidative, reductive, hydrolytic and conjugative pathways. High BCF (>1,000 for algae and fish) and slow depuration (generally in the order of weeks) have been reported for freshwater organisms. Therefore, there is potential for bioaccumulation, although trifluralin is likely to be adsorbed to sediment and therefore its bioavailability is uncertain.

Potential effects on interest features of European marine sites

Potential effects include:

  • toxic effects to algae, invertebrates and fish at concentrations above the EQS of 0.1 mg l -1 (annual average) and 20 mg l-1 (maximum allowable concentration) in the water column;
  • accumulation in sediments but there is no evidence of effects on sediment-dwelling organisms;
  • potential to bioaccumulate but there is no evidence of bioaccumulation in marine organisms, including fish, birds and Annex II sea mammals;
  • trifluralin has been identified as an endocrine disrupting substance and a precautionary approach should be adopted in its control.

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