Exxon Valdez's human toll is still unknown

日期:2019-03-04 03:16:01 作者:石鲞 阅读:

By LEIGH DAYTON in SEATTLE FOUR MONTHS after the Exxon Valdez ran aground in Alaska spilling 35 000 tonnes of crude oil into Prince William Sound, scientists have little idea about the risks to the health of people living in the area or mopping up the spill. They have, however, identified research goals that must be met before they can tease out the implications for human health of the worst oil spill in American waters. Scientists meeting in Seattle, Washington last month blamed much of the uncertainty on the ‘very disturbing’ lack of advance planning by officials and scientists. Olof Linden of the Swedish Environmental Research Institute in Stockholm said: ‘One lesson – one very, very clear lesson – is that it is too late to start planning the follow-up studies when the spill has already taken place.’ Although scientists arrived in Alaska hours after the spill, no formal plan was in place and efforts to coordinate research efforts were made ‘on the run’ by the state Department of Environmental Conservation. Public safety hardly figured in the plans for research. ‘I was amazed at the lack of information we have,’ said David Rall of the US National Institute of Environmental Health Sciences (NIEHS). Scientists working for Exxon and for the State of Alaska are looking at the extent of contamination to a range of edible species, but the enormous numbers of samples needed will take many months to analyse. In the meantime, data are trickling in on the chemical composition of the spilled oil. The composition affects the way the oil weathers, both in water and on shore, and how toxic it is to animals. The findings so far are inconsistent, however. For example, Roger Florky of Exxon Corporation reported finding no benzene in oil samples, whereas Eric Shortt of the Alaska Department of Labor did. Benzene is one of the most biologically active components of crude oil. Although it evaporates within a few days, it is a hazard to people in the early stages of cleaning up oil spills. Different findings may result from different methods of analysis. More important, says Richard Griesemer of the NIEHS’s National Toxicology Program, is the ‘representativeness’ of oil samples. Oil is a complex cocktail of hundreds of chemicals. Its composition varies according to age, weathering and location. Griesemer called for the establishment of a ‘respository of chemically characterised samples’ that all researchers could consult. This would help to guarantee that data are comparable. At present, scientists work on widely disparate samples. Scientists at the Seattle meeting agreed on the need to analyse the Prudhoe Bay oil now flowing from the Trans-Alaskan pipeline which terminates in Valdez. They want to know how those samples compare with samples taken since the spill. The results could help to avoid what Gilbert Omenn of the University of Washington called ‘a new generation of total confusion’ when more laboratory studies are finished in the near future. Oil is not the only hazard that the teams of workers encounter. Many of the solvents with which they decontaminate their clothing and equipment contain harmful substances which need to be analysed. Griesemer also called for the rapid development of reliable tests to determine if a person has been exposed to oil, the degree of any exposure and the fate of the oil once it enters the body. Tests of this sort are relatively simple with single chemicals, but have proven very difficult with substances such as crude oil. No one has yet studied the effects of crude oil on humans. Existing evidence comes from toxicology studies on rats and rabbits, and from the pathology work done on otters and other sea mammals killed by the spill (see ‘Alaska has its fill of oil’, this issue). Because these studies on animals show that crude oil can damage many different organs, especially the liver and kidneys, as well as disrupting the reproductive and immune systems, some scientists would like to clarify the relationship between exposure and physical change. Epidemiological studies of people working on the spill could help investigators to link the animal findings to humans. However, Philip Landrigan of Mount Sinai School of Medicine in New York cautioned that such studies are expensive and disrupt local communities. He said that a small working group, possibly under the direction of the Alaska health department, should develop a formal strategy for such studies. Landrigan also highlighted the importance of tracking the effects of chronic exposure to oil with biological markers, rather than ‘waiting for tumours to occur or dead bodies to pile up’. But time is running out for all scientific work in Prince William Sound – Exxon plans to pull out its teams of emergency workers on 15 September,