exposed subjects at both their initial and at their 7-year follow-up visits. The incidence of the most frequently occurring illness symptoms was comparable at both their initial and at their 7-year follow-up visits. However, at the 7-year follow-up visit, 91% of the oil spill exposed subjects had progressive deterioration of their respiratory system and developed chronic rhinosinusitis and 45% of the exposed workers had developed chronic reactive airway dysfunction syndrome as new symptoms that were not reported during their initial visit (Table 2).The abnormalities in the pulmonary function tests experi-enced by the oil spill cleanup workers during their initial and later follow-up visits are illustrated in Figure 2. The pulmonary function abnormalities are categorized as normal, mild, moder-ate, and severe based on their intensity. Of the 44 oil spill cleanup workers, 37 (84%) had normal pulmonary functions at their earlier initial visit after exposure to the oil spill. However, 7 years later after the oil spill, only 18 (48%) cleanup workers had normal pulmonary functions. Mild pulmonary function abnormalities
In our previous study, we reported early clinical findings among the workers involved in the oil spill cleanup operation (30). In this follow-up study, we have evaluated the long-term effects of this oil spill exposure among those participants involved in its cleanup activities 7 years after their exposure. To the best of our knowledge, this is the first and only longitudinal study that has evaluated any of the long-term hematological or hepatic adverse health effects of the Gulf oil spill among those subjects involved in its cleanup activities 7 years after the disaster. In addi-tion, this study has evaluated the long-term illness symptoms and complaints, as well as pulmonary and cardiac functions seen in the oil spill exposed cleanup workers (30).Assessment of hematological markers such as WBC counts, platelet counts, hemoglobin, hematocrit, BUN levels, etc. are routinely used to diagnose a variety of human diseases includ-ing malignant tumors. The findings of this longitudinal study performed 7 years after the occurrence of the oil spill disaster shows that subjects who had participated in the cleanup activities had altered profiles of their hematological and hepatic functions when compared with those of the unexposed subjects. More spe-cifically, the oil spill exposed workers had persistently increased mean WBC counts, hemoglobin, hematocrit, APS, AST, and ALT, and reduced platelet counts as well as BUN levels even 7 years after the oil spill disaster. The findings of this study support our previous study findings in which we reported that those workers who were exposed to the oil spill during its cleanup operations had significant hematological and hepatic alterations (30). Another important finding of this long-term study is that most workers have now developed chronic rhinosinusitis (91%) and reactive airway dysfunction syndrome (45%) as new symptoms up to 7 years after their oil spill exposure. These symptoms were not routinely reported during their initial visit which occurred soon after their oil spill exposure. There are no existing studies in literature assessing the long-term human health effects of an oil spill exposure on the hematological, hepatic, pulmonary, or cardiac functions to compare with our study findings.The long-term effects of the BP oil spill on exposed cleanup workers produced an increased prevalence of illness symptoms such as shortness of breath, headaches, skin rash, chronic cough, weakness, dizzy spells, painful joints, and chest pain 7 years after their exposure to the oil spill. Previously, several studies have likewise reported an incidence of acute somatic symptoms in oil spill exposed or oil polluted subjects (8, 23–26, 35, 36). However, one study by Zock and coinvestiga-tors (28) assessed long-term respiratory symptoms in cleanup workers 5 years after their exposure to the Prestige oil spill. These authors reported that the oil spill exposed workers had persistent respiratory symptoms including shortness of breath, wheeze, cough, and phlegm 5 years after their exposure to the oil spill (28). The findings of the long-term persistent respiratory health effects of the Prestige oil spill exposure support our study findings. The results of our study further reveal that intensive participation even for short periods (only few weeks) in the oil spill cleanup work activities has resulted in persistent long-term adverse health effects. The GuLF STUDY which is a prospective study designed to investigate the relationships between oil spill exposures and multiple potential physical and mental health
initial and 7-year follow up visits after the disaster. While we rec- ognize that measuring oil spill exposure is difficult due to a lack of validated methodologies and tools of the actual exposure amount that each worker received. We believe it is very unlikely that there was much exposure misclassification of the study participants who were involved in the oil spill cleanup activities.
Despite these study limitations, our findings can clearly demonstrate that exposure to an oil spill is associated with both short-term and long-term adverse health effects in workers involved in its cleanup operations. Specifically, the people who participated in the cleanup activities of the BP oil spill experienced persistent alterations or worsening of their hematological, hepatic, pulmonary and cardiac functions, and prolonged illness symptoms that were still present or worsened 7 years after their exposure. These findings further suggest that workers who are involved in oil spill cleanup operations should be followed consistently over time to detect any long-term toxicities of their oil spill exposure. Since the oil spill contained carcinogenic agents, a latent period exists before these worsen- ing symptoms manifest themselves and progress to malignant diseases. Serial periodic health checkups and routine laboratory blood work as well as high-resolution imaging and pulmonary and cardiac function assessments are necessary to monitor the long-term adverse health effects in workers who participate in oil spill cleanup activities to detect any future malignant transformation.
CONCLUSION
The results of this long-term investigation indicate that subjects involved in the BP oil spill cleanup operations experienced persistent alterations in their hematological, hepatic, pulmonary, and cardiac functions. The hematological alterations include increased mean WBC counts, hemoglobin, hematocrit, and reduced platelet counts as well as BUN levels among the oil spill cleanup workers even 7 years after the oil spill disaster. Hepatic