Thyroxine and Free Thyroxine Levels in Workers Occupationally Exposed to Inorganic Lead

Background The effects of lead exposure on thyroid function are unclear. Methods Serum thyroxine (T4) was evaluated among 137 lead-exposed workers and 83 non-exposed workers. Free thyroxine (FT4) was evaluated among a subset of these workers. Exposure metrics included blood lead level (BLL), which reflects recent exposure, zinc protoporphyrin (ZPP), a marker of intermediate-duration lead exposure, exposure duration, and estimated cumulative exposure. Multiple linear regression results were adjusted for age, race, and current smoking status. Results Mean BLLs were 38.9 μg/dL in lead exposed workers and 2.1 μg/dL in non-exposed workers. The adjusted mean T4 and FT4 concentrations among exposed and non-exposed workers were similar. While T4 was not significantly related to any of the exposure metrics, FT4 was inversely related to the logged values of both exposure duration and cumulative exposure, but not to ZPP or BLL. Conclusions The findings suggest that FT4 levels may be related to long-term lead exposure

Impact of Temperature Acclimation on Photosynthesis in the Toxic Red-Tide Dinoflagellate \u3cem\u3eAlexandrium Fundyense\u3c/em\u3e (Ca28)

This study assessed the impact of temperature on the photosynthetic activity in the dinoflagellate Alexandrium fundyense (Ca28) for cultures grown at 75 µmol photons m–2 s–1 over a range of temperatures. Increasing light intensity under static temperatures caused a 5-fold decrease in the maximum quantum yield for photosystern II (PSII) (FvlFm) Carbon fixation rates mirrored high-light depressions in (FvlFm). Cells in the presence of streptomycin showed an 83% recovery in (FvlFm); therefore, only a minor proportion of the decline in (FvlFm)was attributable to PSII damage by bright light. For cells transferred to higher temperatures, F. was less sensitive to high light, decreasing only 20–40% compared to the 80–90% decrease observed for cells incubated at their ambient growth temperature. For cells shifted to higher temperatures, the rapid recovery phase of (FvlFm) was not present; therefore, cells did not initiate downregulation of PSII. Higher capacity to maintain electron transport, as indicated by the quantum yields, was confirmed by enhanced carbon fixation. Shifts lower temperatures significantly increased PSII sensitivity to high light. Overall, these relationships reflect the synergy between photosynthetic light and dark reactions which are differentially impacted by changes in temperature

Persistence of multiple illnesses in World Trade Center rescue and recovery workers: A cohort study

More than 50 000 people participated in the rescue and recovery work that followed the Sept 11, 2001 (9/11) attacks on the World Trade Center (WTC). Multiple health problems in these workers were reported in the early years after the disaster. We report incidence and prevalence rates of physical and mental health disorders during the 9 years since the attacks, examine their associations with occupational exposures, and quantify physical and mental health comorbidities. In this longitudinal study of a large cohort of WTC rescue and recovery workers, we gathered data from 27 449 participants in the WTC Screening, Monitoring, and Treatment Program. The study population included police officers, firefighters, construction workers, and municipal workers. We used the Kaplan-Meier procedure to estimate cumulative and annual incidence of physical disorders (asthma, sinusitis, and gastro-oesophageal reflux disease), mental health disorders (depression, post-traumatic stress disorder [PTSD], and panic disorder), and spirometric abnormalities. Incidence rates were assessed also by level of exposure (days worked at the WTC site and exposure to the dust cloud). 9-year cumulative incidence of asthma was 27\ub76 (number at risk: 7027), sinusitis 42\ub73 (5870), and gastro-oesophageal reflux disease 39\ub73 (5650). In police officers, cumulative incidence of depression was 7\ub70 (number at risk: 3648), PTSD 9\ub73 (3761), and panic disorder 8\ub74 (3780). In other rescue and recovery workers, cumulative incidence of depression was 27\ub75 (number at risk: 4200), PTSD 31\ub79 (4342), and panic disorder 21\ub72 (4953). 9-year cumulative incidence for spirometric abnormalities was 41\ub78 (number at risk: 5769); three-quarters of these abnormalities were low forced vital capacity. Incidence of most disorders was highest in workers with greatest WTC exposure. Extensive comorbidity was reported within and between physical and mental health disorders. 9 years after the 9/11 WTC attacks, rescue and recovery workers continue to have a substantial burden of physical and mental health problems. These findings emphasise the need for continued monitoring and treatment of the WTC rescue and recovery population. Centers for Disease Control and Prevention and National Institute for Occupational Safety and Health. \ua9 2011 Elsevier Ltd