Chronic hepatitis C virus (HCV) infection and heavy alcohol consumption (>50 to 70 g per day) are major risk factors in low-risk areas such as the U.S. Predominant HCC risk factors in most high-risk areas, such as parts of Asia, include chronic hepatitis B virus (HBV) infection and consumption of aflatoxin-contaminated foods ( Yu and Yuan, 2004).
Many HCC cases are diagnosed at a regional or distant stage (49% between 20) ( National Cancer Institute, 2014b), which contributes to the low five-year 16.6% relative survival rate in the U.S. The mean age at diagnosis is 64 years (median 63) ( National Cancer Institute, 2014b). In the U.S., HCC is more common among males and among individuals of Asian descent ( Altekruse et al., 2009). Primary liver cancer is the sixth most common cancer in the world and the second leading cause of cancer-related death ( Ferlay et al., 2013), and between 70 and 85% of primary liver cancer cases are HCC ( Jemal et al., 2011). Pesticides are less likely to degrade within homes due to the absence of moisture, sunlight, and microorganisms ( Gunier et al., 2011 Ritz and Rull, 2008), and humans can be subsequently exposed via dermal contact and ingestion ( Gunier et al., 2001).Įpidemiologic studies have shown that pesticide exposure may increase the risk of hepatocellular carcinoma (HCC). (2011) demonstrated that residential proximity within 1,250 m of pesticide-treated crops in California was significantly correlated with pesticide concentrations in sampled carpet dust.
Vulnerable populations include rural residents and farming families ( Ward et al., 2000), as pesticides can enter homes through drift and from clothing ( Ritz and Rull, 2008). Applied pesticides can drift from their intended sites through the air and ground via spray drift and post-application volatilization ( Rull and Ritz, 2003). Additional sources of exposure include occupation (e.g., pest control) and very importantly, residential proximity to agricultural pesticide applications.
In the U.S., pesticides are commonly used in agriculture and horticulture and exposure occurs most frequently via diet ( Dich et al., 1997 Ritz and Rull, 2008). Pesticide use, particularly among herbicides, rapidly increased between 19 in the U.S., and has since experienced fluctuations in use due to changes in planted acreage, pest infestation, and Integrated Pest Management (e.g., crop rotation) ( Fernandez-Cornejo et al., 2014). Pesticides, an environmental exposure comprised of widely used chemicals designed to treat pests (e.g., insects), have been associated with adverse human health outcomes such as cancers ( Alavanja et al., 2004 Blair et al., 2015).