Pollutant threat to oyster industry

17 July 2003

A study published today reveals that a common industrial chemical causes sexual deformities in oysters, producing large numbers of hermaphrodite animals. The chemical, nonylphenol, is a breakdown product from a surfactant widely used in detergents, dispersing agents, herbicides, spermicides and cosmetics.

Dr Helen Nice who undertook this study at Royal Holloway, University of London, says, "Our results may cast doubt on the widespread use of this chemical in many human products including contraceptive spermicides."

Nonylphenol is a known endocrine disrupter - chemicals that interfere with the hormones of animals. It is discharged through sewage effluent and is therefore widespread in the aquatic environment.

Dr Nice, together with supervisors Professor Mike Thorndyke, Dr. Mark Crane and Dr. Dave Morrit, worked in collaboration with Seasalter Shellfish, a commercial oyster hatchery at Whitstable in Kent. She exposed oyster larvae, Crassostrea gigas, to environmentally realistic levels of nonylphenol, the breakdown product of a surfactant.

Her research shows that developing embryos and larvae exposed to levels as low as 0.1 micrograms per litre experience delays in development, show abnormalities in the shell hinge and increased death rates. Nearly a third of the larvae that survived treatment with the pollutant developed into hermaphrodite adults (both sex organs present). But there were no hermaphrodites in the control oysters that were not exposed to the pollutant. Oysters are known for their ability to change sex from one season to the next, but they are either male or female, not bisexual.

These adverse effects are seen even when oysters are exposed to levels well below those currently considered safe. The Environment Agency has set current recommended safe levels in both fresh and marine water at an average of 1.0 micrograms per litre, ten times higher than used in this work.

The implications for oyster cultivation are that bisexual animals self fertilise, producing offspring that do not survive to breed themselves.

Dr Nice says, "The Pacific oyster plays a vital role in many food webs and is commercially important worldwide. These results are worrying, not only because of the damage to the oysters themselves, but also because this chemical may well be affecting other organisms sharing their environment. The findings reported here resulted from brief, single exposures to nonylphenol at critical periods in the animals’ development. It is vital when chemicals are screened, that the effects on vulnerable developmental stages should be considered. We clearly need further research to find out exactly what harm this chemical does and if it can harm people."

Further information

NERC Press Office
Natural Environment Research Council
Polaris House, North Star Avenue
Swindon, SN2 1EU
Tel: 01793 411561
Mob: 07917 557215

Helen Nice
Mob: 61 (0) 410 055763

Professor Mike Thorndyke
Tel: 01276 850490
Mob: 46 (0)70 2423 119

Katie Price
Royal Holloway Press Office
Tel: 01784 44396

Notes

1. The results of the study are published on July 17, 2003 in Marine Ecology Progress Series Volume 256:293-300, a scientific journal that serves as a worldwide forum for all aspects of marine ecology, fundamental and applied.

2. The research by Dr Nice was funded by a studentship from the Natural Environment Research Council (NERC) associated with a grant from the NERC Developmental Ecology of Marine Animals (DEMA) Thematic Programme. Dr Nice worked with supervisors Professor Mike Thorndyke, Dr Mark Crane and Dr Dave Morritt of Royal Holloway.

3. Nonylphenol originates from alkylphenol polyethoxylates, non-ionic surfactants with a wide variety of industrial, agricultural and household applications, and is used in detergents, dispersing agents, herbicides, spermicides and cosmetics. Alkylphenol polyethoxylates breakdown readily in aerobic conditions to nonylphenol, a relatively stable compound that degrades slowly. Nonylphenol tends to accumulate in sediments. It also accumulates in the tissues of a range of aquatic organisms.

4. Dr Helen Nice is presently providing technical expertise on an endocrine disruption research program in the Environment and Innovation Division of Sydney Water Corporation, Australia.

5. Professor Michael Thorndyke is Visiting Professor in Experimental Marine Biology at Royal Holloway, University of London and Chair of Experimental Marine Biology at the Royal Swedish Academy of Sciences.

6. The UK Natural Environment Research Council funds and carries out impartial scientific research in the sciences of the environment. NERC trains the next generation of independent environmental scientists.

7. Royal Holloway, a multi-faculty college of the University of London, enjoys an international reputation for the highest quality teaching and research across the sciences, arts and humanities (Ranked 9th in the UK for research by the Financial Times). Royal Holloway is home for a vibrant community of 6,000 undergraduate and postgraduate students from more than 120 countries.

Press release: 13/03

Pollutant threat to oyster industry

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