Human Biomonitoring of Environmental Chemicals

be controlled most rigorously? One strategy is to go after the largest sources of pollution. This approach cer tainly makes sense when those pollu tants have obvious and widespread consequences, such as warming the globe, causing algal blooms, eroding the ozone layer or killing off wildlife. But for protecting human health, this strate gy does not serve so well, because the link between a given compound and its biological effects can be difficult to gauge. For epidemiologists to correlate environmental pollutants with health problems, they need to know who has been exposed and at what level. This knowledge is exceptionally dif ficult to gain when there is a lag be tween exposure and the manifestation of illness. In such cases, the data are seldom?if ever?sufficient to deter