Extremely complex interactions may occur when subjects are exposed to multiple pollutants. There are many unsettled issues and unknowns here. It is not essential that individual pollutants (such as heavy metals) should exceed reference or limit values. Additive, superadditive or even antagonistic effects are possible here, although only initial studies have been performed. Detailed recent studies have shown that lead does indeed cause a variety of adverse effects besides its well known neuro-toxicity and hematotoxicity. Timely and sensitive biomonitoring can help in clarifying the etiology, or in confirming or excluding the etiological role of lead.
Exposure biomonitoring alone is generally not helpful in risk assessment or in determining the etiology of a disease when the exposure is long past. As our article describes, biochemical and biological effect monitoring (such as DNA- or protein-adduct formation or chromosomal aberrations [1, 2]) are capable of recording long-term effects and can lead to important new information about dose-effect relationships at the molecular level. These validated toxicological data may be combined with other procedures, such as occupational medical assessments, and analyzed by mathematical models to give more precise risk assessments.
What is important is that biomonitoring results of this kind should be interpreted in the context of clinical findings. Evaluation of carcinogenic effects must include the long periods of latency, individual susceptibility and cocarcinogenic aspects. The medical advisory committee on occupational diseases has recently recommended that the interaction between two occupational agent groups, namely polycyclic aromatic hydrocarbons and cocarcinogenic asbestos fibers, should be included in the list of occupational diseases (3).
Classical exposure monitoring can be used in long term studies, for example, to investigate persistent biological substances which are absorbed from the environment and accumulated in the body. The American Environmental Protection Agency and the WHO are currently performing large scale studies to investigate the background exposure of the population to these pollutants (4).
Footnotes
Conflict of interest statement
The authors of all contributions declare that no conflict of interest exists according to the guidelines of the International Committee of Medical Journal Editors.
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