NAPHTHAS: In a large epidemiological study on over 15,000 employees at several
petroleum refineries and amongst residents located near these refineries, no
increased ricks of kidney cancer was observed in association with gasoline
exposures (a similar material). In another similar study, no increased risk of kidney
cancers among service station employees, especially after a 30-year latency period.
BENZENE: Studies of Workers Overexposed to Benzene: Studies of workers
exposed to benzene show clear evidence that overexposure can cause cancer and
other diseases of the blood forming organs including Acute Myelogenous Leukemia
(AML), and Aplastic Anemia (AA), an often fatal disease. Some studies suggest
overexposure to benzene may also be associated with Myelodysplastic Syndrome
(MDS). Findings from a Case-Control study of workers exposed to benzene was
reported during the 2009 Benzene Symposium in Munich included an increase in
Acute Myeloid Leukemias and Non-Hodgkins Lymphoid Neoplasms (NHLN) of the
subtype follicular lymphoma (FL) in some occupational categories. Some studies of
workers exposed to benzene have shown an association with increased rates of
chromosome aberrations in circulating lymphocytes. One study of women workers
exposed to benzene suggested a weak association with irregular menstruation.
However, other studies of workers exposed to benzene have not demonstrated clear
evidence of an effect on fertility or reproductive outcome in humans. Benzene can
cross the placenta and affect the developing fetus. Cases of AA have been reported
in the offspring of persons severely overexposed to benzene. Studies in laboratory
animals indicate that prolonged, repeated exposure to high levels of benzene vapor
can cause bone marrow suppression and cancer in multiple organ systems. Studies
in laboratory animals show evidence of adverse effects on male reproductive organs
following high levels of exposure but no significant effects on reproduction have been
observed. Embryotoxicity has been reported in studies of laboratory animals but
effects were limited to reduced fetal weight and minor skeletal variations. Benzene
has been classified as a proven human carcinogen by OSHA and a Group 1
(Carcinogenic to Humans) material by IARC.
The current proposed IARC classification for benzene is summarized as follows:
Sufficient evidence for Acute Myeloid Leukemia; limited evidence for Acute
Lymphatic Leukemia, Chronic Lymphatic Leukemia, Non-Hodgkin Lymphoma, and
TARGET ORGANS AFFECTED:Central nervous system, heart, eyes, skin, liver, kidney, blood bone marrow, and numerous additional unknown effects.