California Public Health Goals

On Friday, July 28, the California Office of Environmental Health Hazard Assessment, or OEHHA (people just say “Oh-we-ha” for short – sounds like something you’d say at a rodeo), set the Public Health Goal (PHG) for chromium 6 at 0.020 ug/L. That will start the process moving forward toward setting a Maximum Contaminant Level (MCL) here in the state of California. But what is a PHG and how are they set by this funny sounding group, OEHHA? For a chemical compound or element that is suspected of having adverse health effects, studies need to be conducted – lot’s and lot’s of studies. These studies can be conducted by OEHHA themselves, or they may use data from other studies conducted by health effects professionals and groups all over the country or even the world. These studies test for carcinogenic (cancer causing) and non-carcinogenic health effects, and many of them focus primarily on those sub-sets of the population that are most at risk, which usually means pregnant women, children, and the elderly. Studies are usually conducted on animals, and then the data is extrapolated to humans, but data may also be obtained from humans in areas where people are actually exposed to the study compound or element because it’s already present in their drinking water or food source. OEHHA looks at all these studies and through the magic of toxicological statistics (at least it seems like magic to me), they come up with a number that they define as the PHG. This number is designed to represent the estimated “one in one million” lifetime cancer risk level for the compound or element in question. This means that for every million people who drink two liters of water with that level of the compound or element daily for 70 years, no more than one person would be expected to develop cancer. The “one-in-one million” risk level is widely accepted by doctors and scientists as the “negligible risk” standard. One of the difficulties with setting these PHG’s is that many times, the data from all those health effects studies is not as straight forward as it may seem. There is a lot of interpretation that goes on, and the OEHHA, like most health effects groups, tend to be conservative in how things are interpreted, resulting in very conservative numbers. Of course, this also results in a good deal of controversy, discussion, and misunderstanding surrounding any PHG. Once a PHG has been set, the process for determining an MCL begins, and that must take into account a lot of other information, such as whether the compound or element is present in drinking water; if laboratory methods exist to detect it in drinking water; and if there are best available technologies (BAT) available to treat for it at a reasonable cost.