Relationship between cyanobacterial bloom impacted drinking water sources and hepatocellular carcinoma incidence rates.

Freshwater cyanobacterial blooms have increased in geographic distribution and intensity in recent decades worldwide. Cyanotoxins produced by many of these blooms, such as microcystins, are observed to play a role in tumor promotion and have been associated with increased liver cancer rates at the population level. Exposure occurs primarily via contaminated water (ingestion, inhalation, dermal contact), either from treated drinking water or during recreation in impacted surface waters; additional sources of exposure include consumption of fresh produce grown in cyanotoxin-contaminated environments or through the consumption of seafood caught in bloom-impacted waters. The current ecological study investigates whether populations served by cyanobacterial bloom-impacted surface waters for their drinking water source have higher hepatocellular carcinoma (HCC) incidence rates than those served by non-impacted surface waters and groundwater. Census tract level cancer incidence in the state of Ohio, United States was modeled using a negative binomial generalized linear model, controlling for differences in demographic composition (e.g. age, race, and income) at the census tract level. Presence of cyanobacterial blooms in surface waters was estimated using satellite multi-spectral remote sensing and in situ public water system cyanotoxin monitoring data. Census tracts estimated to be served by bloom-impacted surface waters had 14.2% higher HCC incidence rates than those served by non-bloom-impacted surface waters (incidence rate ratio, IRR: 1.142; 95% CI: 1.037-1.257). Additionally, these bloom-impacted census tracts had a 17.4% higher HCC incidence rate as compared to those estimated to receive drinking water from a groundwater source (IRR: 1.174; 95% CI: 1.101-1.252). No statistical difference was found in HCC incidence rates when comparing areas presumed to be served by non-bloom-impacted surface waters and those presumed to be served by groundwater sources. An important consideration for environmental justice, areas estimated to be served by bloom-impacted surface waters had higher levels of poverty and included a higher percentage of racial and ethnic minority populations than areas served by groundwater. These findings support the need for additional in-depth research into the potential hepatic carcinogenicity and exposures of cyanotoxins in those areas where severe blooms are chronically observed.

Air infiltration in low-income, urban homes and its relationship to lung function.

Previous research has found increased home ventilation, which may affect health by altering the composition of indoor air, is associated with improvement of respiratory health, but evidence linking home ventilation to objectively measured lung function is sparse. The Colorado Home Energy Efficiency and Respiratory health (CHEER) study, a cross-sectional study of low-income, urban, nonsmoking homes across the Northern Front Range of Colorado, USA, focused on elucidating this link. We used a multipoint depressurization blower door test to measure the air tightness of the homes and calculate the annual average infiltration rate (AAIR). Lung function tests were administered to eligible participants. We analyzed data from 253 participants in 187 homes with two or more acceptable spirometry tests. We used generalized estimating equations to model forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FEV1/FVC z-scores as a function of AAIR. AAIRs ranged from 0.10 to 1.98 air changes per hour. Mean z-scores for FEV1, FVC, and FEV1/FVC were -0.57, 0.32, and -0.43, respectively. AAIR was positively associated with increased FEV1/FVC z-scores, such that a 1-unit change in AAIR corresponded to a half of a standard deviation in lung function (ß = 0.51, CI: 0.02-0.99). These associations were strongest for healthy populations and weaker for those with asthma and asthma-like symptoms. AAIR was not associated with FEV1 or FVC. Our study is the first in the United States to link home ventilation by infiltration to objectively measured lung function in low-income, urban households.