Exogenous shocks to the human sex ratio: the case of September 11, 2001 in New York City

BACKGROUND: The human secondary sex ratio reportedly falls in populations subjected to exogenous stressors such as earthquakes or political and social upheavals. Explanations of the association include reduced conception of males and increased fetal deaths among males. The latter explanation has been supported by research reporting that the sex ratio in California fell 3 months, but not 8, 9 or 10 months, after the terrorist attacks of September 11, 2001. California's distance from the attacks raises the questions of whether the results arose from chance and would be found elsewhere. We contribute to the literature by testing the association between the secondary sex ratio and the events of September 11 in New York City. METHODS: We replicate the California tests by applying interrupted time-series methods, which control for secular trends, seasonality and other forms of autocorrelation, to 91 cohorts born in New York City during 28-day periods from January 1996 to June 2002. RESULTS: As hypothesized, the sex ratio in New York City in the period 1 January to 28 January 2002 fell to 1, which was the lowest observed value during the test period and significantly (i.e. P < 0.01, two-tailed test) below the value expected from history. CONCLUSIONS: Our findings support the male fetal loss explanation of the association between exogenous population shocks and the secondary sex ratio.     

Chitotriosidase is a Biomarker for the Resistance to World Trade Center Lung Injury in New York City Firefighters

Purpose

World Trade Center (WTC) exposure caused airflow obstruction years after exposure. Chitinases and IgE are innate and humoral mediators of obstructive airway disease. We investigated if serum expression of chitinases and IgE early after WTC exposure predicts subsequent obstruction.

Methods

With a nested case–control design, 251 FDNY personnel had chitotriosidase, YKL-40 and IgE measured in serum drawn within months of 9/11/2001. The main outcome was subsequent Forced Expiratory Volume after 1 second/Forced Vital Capacity (FEV₁/FVC) less than the lower limit of normal (LLN). Cases (N?=?125) had abnormal FEV₁/FVC whereas controls had normal FEV₁/FVC (N?=?126). In a secondary analysis, resistant cases (N?=?66) had FEV₁ (≥107 %) one standard deviation above the mean. Logistic regression adjusted for age, BMI, exposure intensity and post-exposure FEV₁/FVC modeled the association between early biomarkers and later lung function.

Results

Cases and Controls initially lost lung function. Controls recovered to pre-9/11 FEV₁ and FVC while cases continue to decline. Cases expressed lower serum chitotriosidase and higher IgE levels. Increase in IgE increased the odds of airflow obstruction and decreased the odds of above average FEV₁. Alternately, increasing chitotriosidase decreased the odds of abnormal FEV₁/FVC and increased the odds of FEV₁?≥?107 %. Serum YKL-40 was not associated with FEV₁/FVC or FEV₁ in this cohort.

Conclusions

Increased serum chitotriosidase reduces the odds of developing obstruction after WTC-particulate matter exposure and is associated with recovery of lung function. Alternately, elevated IgE is a risk factor for airflow obstruction and progressive lung function decline.