Occupational Bladder Cancer in a 4,4′-Methylenebis(2-chloroaniline) (MBOCA)-Exposed Worker

Abstract

A 52-year-old male chemical worker was admitted to the hospital with a history of paroxysmal microscopic hematuria for about 2 years and nocturia with gross hematuria about five times per night for 2 months. He was a nonsmoker and denied a history of any other bladder carcinogen exposure except for occasional pesticide application during agricultural work. Intravenous urogram imaging showed a mass occupying half of the bladder capacity. Cystoscopy revealed a mass over the left dome of the bladder. Cystoscopic biopsy revealed a grade 3 invasive transitional cell carcinoma with marked necrosis. From 1987 until hospital admission in 2001, the patient had worked in a company that produced the 4,4′-methylenebis(2-chloroaniline) (MBOCA) curing agent. He did not wear any personal protective equipment during work. Ambient air MBOCA levels in the purification process area (0.23–0.41 mg/m3) exceeded the U.S. Occupational Safety and Health Administration’s permissible exposure level. Urinary MBOCA levels (267.9–15701.1 μg/g creatinine) far exceeded the California Occupational Safety and Health Administration’s reference value of 100 μg/L. This patient worked in the purification process with occupational exposure to MBOCA for 14 years. According to the environmental and biologic monitoring data and latency period, and excluding other potential bladder carcinogen exposure, this worker was diagnosed as having occupational bladder cancer due to high exposure to MBOCA through inhalation or dermal absorption in the purification area. This case finding supports that MBOCA is a potential human carcinogen. Safe use of skin-protective equipment and respirators is required to prevent workers from MBOCA exposure.

Oxidative DNA Damage Estimated by Plasma 8‐hydroxydeoxyguanosine (8‐OHdG): Influence of 4, 4'‐methylenebis (2‐chloroaniline) Exposure and Smoking

“…We previously reported one incidence of MBOCAinduced bladder cancer for a 52-yr-old male who had worked in one of the four MBOCA-producing companies of the present study for 14 yr 3) . In addition, we conducted a bladder cancer screening program in the four MBOCAproducing factories 12) .…”

“…MBOCA is considered to probably be carcinogenic to humans by the International Agency of Research on Cancer and other Agents 2,3) . The precise mechanism of action of MBOCA is not completely understood.…”

“…The US Environmental Protection Agency (EPA) has determined that MBOCA is a probable human carcinogen (2A). The National Toxicology Program 10th Report on Carcinogens (NTP, 2002) also declares that MBOCA may reasonably be anticipated to be a human carcinogen 2,3) . Our recent paper reported a sentinel case of transitional cell carcinoma of the urinary bladder in one worker with 14 yr of occupational exposure to MBOCA in Taiwan 3) .…”

“…The National Toxicology Program 10th Report on Carcinogens (NTP, 2002) also declares that MBOCA may reasonably be anticipated to be a human carcinogen 2,3) . Our recent paper reported a sentinel case of transitional cell carcinoma of the urinary bladder in one worker with 14 yr of occupational exposure to MBOCA in Taiwan 3) . Although the carcinogenicity of MBOCA has been recognized, the mechanism leading to the development of bladder cancer is unclear.…”

Occupation and Cancer

“…The incidence of bladder cancer is the highest in industrialized countries, and the incidence in less developed countries is about 70% lower than in the United States. 2,3,11,19,20 A substantial evidence exist for an increased risk of bladder cancer among plumbing, tobacco, metal, heating and air conditioning workers. 11,[21][22][23] The latency period between exposure and bladder cancer was estimated to be about 20 years.…”