Assessing the Health Status and Mercury in Urine of Workers on an Offshore Facility (Platform) in the Philippines
Authors: Junio-Ramirez Elena 
Published: December 2007

Introduction

The facility is a natural gas Platform, which utilizes this clean, indigenous fuel lying 3,000 meters below seabed at 830m as an energy resource. The field contains natural reserves of at least 2.7 trillion cubic feet (Tcf) and 85 million barrels of condensate, more than enough to provide 2,700 MW of power for an extensive period of more than 20 years. It is a project operated by Joint Venture partners (JV).

The smooth operation of the project is the Operating Company's concern, and this is made possible by providing the workers with a safe and healthy workplace. To promote the overall well-being of workers, the company conducts regular assessment of workers' health.

In connection with this, a medical monitoring of workers in the company was conducted to ensure early detection of adverse health effects from exposures to potential hazards in the workplace. It is important to detect early health defects while it is still reversible and put in place preventive measures.

This periodic health assessment is a back-up program for routine environment monitoring, the primary means of insuring that exposure levels are below those associated with adverse health effects. The medical examination was conducted on the premise that employees are exposed to Mercury, a by-product of the work processes at the Platform and a potential work hazard.

Although mercury in the environment was noted to be low from previous assessment, (0.05 to 0.2 ug/m3,) ACGIH TLV is 25 ug/m3, it is important to monitor and maintain a low level of mercury in workers' body. Health status of the workers will be assessed in relation to their mercury in urine and determine whether a possible correlation exists between them.

The Health Effects of Mercury

Mercury is a metal present naturally at very low concentrations in the atmosphere, water, sediments and tissues of all plants and animals. Mercury and its compound are released into the environment as a result of both natural and man-made activities. It is used as electrode in industrial production of chlorine, manufacture of fungicides, anti-fouling paints, laboratory apparatus, thermometers, detonators, dental amalgams and batteries. Combustion of coal and petroleum products increases slowly the mercury load in atmosphere and even in remote ecosystems.

Mercury is present in numerous chemical forms. In its elemental form, mercury is shiny, silver-white, liquid metal. It can be combined with other chemicals to form inorganic compounds. Mercury can evaporate to form colorless, odorless mercury vapors. It can also combine with organic substances to form organic compounds such as methyl mercury.

Exposure to mercury can occur through inhalation, ingestion or dermal absorption. The amount of mercury absorbed by the body, thus the degree of its toxicity, is dependent upon its chemical forms. For instance, ingested elemental mercury is only 0.01% absorbed, but methyl mercury is 100% absorbed from the gastrointestinal tract. The average half-life in human is about 60 days for inorganic mercury and around 70 days for organic mercury compounds.1 Thus, even though exposure is reduced, the body burden will remain for at least a few months. In the human body, mercury accumulates in the liver, kidney, brain and blood. Mercury may cause acute or chronic health effects.2 Mercury compounds are eliminated gradually in urine, feces, saliva and sweat.

Very high exposures to mercury vapor can cause symptoms which usually begin with cough, chest tightness, trouble breathing and upset stomach. This may go on to pneumonia, which can become fatal. If the inorganic mercury compounds are swallowed, nausea, vomiting, diarrhea and severe kidney damage can occur. Inhalation of 1–3 mg/m3 for 2–5 hours may cause headaches, salivation, metallic taste in the mouth, chills, cough, fever, tremors, abdominal cramps, diarrhea, nausea, vomiting, tightness in the chest, difficulty of breathing, fatigue or lung irritation. Symptoms maybe delayed in onset for a number of hours.