Tittabawassee River Watch Editorial
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David Linhardt, reader response to Midland Daily News Forum 6/6/04:Bioavailability study needed for dioxin
Date:Jun, 06 2004
Mr. Harding's comments on a bioavailability study contains a great deal of misinformation that it is difficult to know where to begin making needed corrections.
Let me address just two points: (1) The number of locations sampled for dioxins is very, very few in in number. In total, only about 70 locations have been sampled -- plus no residential areas have yet to be sampled. The 1983 EPA sampling found TCDD in a range of 3 ppt to 270 ppt. The 1996 DEQ sampling found approximately the same levels of TCDD: 3 ppt to 288 ppt. The forecasted drop in dioxins levels that is the basis for the "wait long enough and all will be well" has yet to occur. There is a reason for why dioxin levels have not dropped as expected -- perhaps, Mr. Harding will enlighten up.
(2) Mr. Harding's support of "bioavailability" (determination of dioxin blood serum levels) has a slight problem -- there is very little data to indicate what levels of blood serum dioxins will result in health risk.
There are perhaps only 3 to 4 quality epidemiology studies that measured both cancer mortality along with dioxin blood serum levels. All were industrial studies and all found that blood serum levels greater than 200 ppt to 300 ppt were associated with statistically significant elevations of cancer mortality.
Suppose some Midland residents are found to have dioxin blood serum levels in the 100 ppt to 150 ppt range -- then what? This is no data that I am aware of that will indicate the health risk from this level of dioxin in the body. Without "sound science" of confirmed health risk, will we act or just wait longer.
One final point, it is well recognized that both young children and nursing infants ingest more dioxins per day that does the average US adult. In fact, the EPA has determined that a nursing infant, whose mother has been exposed to only background levels of dioxins (9.4 ppt-TEQ), will ingest approximately 156 times more dioxins on a daily basis (12 month average) than will the mother. The reason for the difference -- breastmilk is high in dioxins even with only background levels of exposure.
Are the risks to Midland's nursing infants higher because dioxin levels are higher -- who knows -- there is not enough data. We need to study this more -- perhaps, 20 to 30 years might be just right.
The proponents of delay and no remediation until "sound science" is absolutely, positively certain may be endangering the health and development of Midland's youngest citizens and that yet to be born.
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