Occupational lead exposures carcinogenic effects

Due to experimental data, an indirect rather than direct genotoxic carcinogenic effect of lead has been indicated (Silbergeld et al. 2000). Thus, there may be a threshold for the carcinogenic effects in man that would argue in favor of setting health-based occupational exposure limits for lead. 

The objective of this chapter is to put into perspective some of the current knowledge with respect to trace metals and their health implications. Potential adverse health effects of occupational exposures to trace metals are dis cussed cancer (arsenic, beryllium chromium nickel, and perhaps cadmium) chronic lung disease (beryllium and cadmium) neurologic and reproductive disorders (lead and mercury) and kidney disorders (lead and cadmium). Also discussed are the National Institute for Occupational Safety and Health (NIOSH) recommended standards for occupational exposure to several trace metals, the difficulty of establishing safe levels of exposure (particularly for carcinogens), and problems involved in identifying toxic components of trade name products. Special attention is given to the role of chemists to help protect the public health. 

The primary routes of potential human exposure to coke oven emissions are inhalation and dermal contact. Occupational exposure to coke oven emissions may occur for those workers in the aluminum, steel, graphite, electrical, and construction industries. Coke oven emissions can have a deleterious effect on human health. Coke oven emissions contain literally several thousand compounds, several of which are known carcinogens and/or cocarcinogens including polycyclic organic matter from coal tar pitch volatiles, jS-naphthylamine, benzene, arsenic, beryllium, cadmium, chromate, lead, nickel subsulfide, nitric oxide, and sulfur dioxide. Most regulatory attention has been paid to coal tar pitch volatiles. 

Fly ash from municipal waste and industrial waste incinerators contains PCDDs, including TCDD, and PCDFs, which are lipophiles, and heavy metals, including chromium, copper, manganese, vanadium, and lead, which are hydrophiles [29-31]. These chemicals have multiple toxicities, and are known to impact the human liver, immune system, respiratory system, thyroid, male reproductive function, and CNS [32-34]. Several are human carcinogens [32, 35], Enhanced toxic effects are observed for mixtures of some of these [21, 22, 36], The mixtures of toxicants present in fly ash are complex and the mechanisms for their action on the human body are largely unknown. It is known that occupational exposure to fly ash from municipal and industrial waste incinerators increases the blood concentrations of PCDDs and PCDFs [29, 30]. It is also known that heavy metals absorbed from fly ash are translocated from the lungs where they first impact to other body organs where toxic effects are observed [31]. 

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