A lot of the media (and scientific) attention to oil spills in the ocean focuses on the effects on marine ecosystems. The ecological effects, particularly in the short term, are undeniable – the pictures of oil-soaked birds are an obvious example. However, less attention is given to the potential effects on human health – both to those living in communities near the spill, and those involved in the spill clean up. A very timely review by Francisco Aguilera and colleagues, published shortly before the recent BP spill, looked at data from other recent spills; some of the conclusions from this review can be extrapolated to look at the human health implications of the BP spill.
The Aguilera et al. review looked at 3 types of studies:
- in vitro studies and studies on food chain transfer effects;
- epidemiological studies on acute and psychological effects; and,
- epidemiological studies on genotoxicity and endocrine toxicity.
The in vitro studies basically indicated that oil from a spill can affect human cells, including affecting the activity of enzymes associated with carcinogenicity – not particularly surprising to me, and not enough by itself to indicate whether actual human health effects would occur. The food chain transfer studies were fairly relevant; they showed that rats fed mussels from an area affected by an oil spill developed DNA damage, and that this damage was correlated with the amounts of polycyclic aromatic hydrocarbons (PAH), a type of chemical found in oil and known to have carcinogenic properties. DNA damage does not automatically mean cancer will follow, and these studies do not appear to have been followed up with a long-term cancer bioassay (which is very expensive and time consuming), so this doesn’t definitively mean that eating contaminated mussels would lead to cancer, but there’s enough evidence there that I’d be pretty hesitant to eat shellfish from an area recently affected by an oil spill. Typically vertebrates, including fish, are better at metabolizing the PAH than invertebrates such as mussels, so I would expect the effects to be less from eating fish than shellfish.
A variety of epidemiological studies on acute and psychological effects from oil spills were identified. Many of these involved self-reporting of health effects; while I haven’t had the time to look at the original papers, in general this type of study is subject to biases (e.g. someone living near an oil spill may expect to have health effects, and therefore report having them), so it is hard to draw firm conclusions from these studies. However, there were some studies that looked at more quantifiable effects.
Communities affected by oil spills were found to have higher incidences of generalized anxiety disorder and post-traumatic stress disorder shortly after the spill (within a year or so), particularly in aboriginal communities. Given that these communities often have a high level of dependence on the sea, it is perhaps not surprising that worry about their livelihoods being affected would cause stress and anxiety. The area affected by the BP spill has a very different population makeup though, so these results wouldn’t necessarily be directly applicable. There are still going to be people who at least perceive their livelihood or way of life to be affected though, so the potential for psychological effects is there.
Actual health effects in nearby communities over the short-term don’t seem to be very significant. While self-reported poor health was higher in these communities, quantitative measurements of health indicators didn’t seem to show any real effects. However, effects were noted in people responding to oil spills and helping with clean-up, including irritation, body pain, and effects on lung function (generally reversible).
There are also data on genotoxicity and endocrine effects on people involved in oil spill clean-up. Those significantly exposed did show evidence of genetic damage, as well as some hormone changes, and higher than normal levels of heavy metals such as aluminum, nickel and lead in their blood. Genetic damage measured shortly after exposure doesn’t necessarily translate to future cancer, since the body does have repair mechanisms, but it is an indication of carcinogenic potential from the exposure. Only long-term follow up would give a reliable indication, and I don’t think there were enough people in the study groups to get meaningful data.
So what does this mean for the BP spill? I think these data show that health effects in residents of nearby communities aren’t likely from this sort of spill, though psychological effects are possible, and marine food sources should not be harvested from affected areas. Health effects are more likely in volunteers and workers involved in the spill response and clean-up or others directly exposed to the spill; these people should therefore be wearing appropriate protective gear and take other steps to minimize exposures.
Disclaimer: These conclusions are based on generalized extrapolations from other oil spills; since each oil spill is different in terms of the size of release, distribution of contamination, chemical composition of the oil, and setting, they shouldn’t be taken as definitive statements about health effects from the BP spill. However, I think the overall conclusion that health effects are only likely in those directly exposed to the oil (or possibly eating contaminated food sources) is reasonable and supported by our current understanding of the environmental fate and toxicity of crude oil components.
Aguilera, F., Méndez, J., Pásaro, E., & Laffon, B. (2010). Review on the effects of exposure to spilled oils on human health Journal of Applied Toxicology DOI: 10.1002/jat.1521