woensdag 20 augustus 2014

US review: blood concentration of drugs 1000x times higher than pollutants

Rappaport et al (2014)  investigated the occurrence of chemicals in blood of healthy human populations from the US. They classified the chemicals in 4 groups:
  1. endogenous chemicals (from intrinsic human metabolism), 
  2. food chemicals,
  3. pollutants or,
  4. drugs.
In total blood concentrations of 1,561 chemicals were obtained. They reported, among other obeservations, that blood concentrations of pollutants were 1,000 times lower than those of medicinal drugs. Figure 2 of their paper is added below.

The paper shows convincingly that concentrations of exogeneous medicinal drugs are - in average -3 orders of magnitude higher than pollutants! That really pose the question: how is the balance between adverse health effect caused by drugs and health effects of pollutants? Are pollutants indeed the priority chemicals when studying environmental health issues?

dinsdag 19 augustus 2014

Study of nanocoated material did not show translocation to remote organs

Just published! A German study by Fraunhofer of toxicity of nanoparticles with the same core but different chemical surface modifications. Conclusions are:
"This study compared the toxic effects of a triple of TiO2 nanoparticles after a 28-day nose-only inhalation. Three TiO2 varieties used for this study did not show pronounced differences in the exhibited toxicity. Thus, the variation in properties regarding crystal structure and surface modification did not alter considerably the interactions with biological structures in the respiratory tract. This was not expected as surface modifications sometimes are reported to trigger a dramatically increased toxic potential as compared to uncoated core particles. Translocation to remote organs was negligible and values higher than the detection of limits observed in some few animals. This confirms for the poorly soluble TiO2 particles no considerable translocation to liver and no translocation at all to brain."


Full study report

Remarkeble! But how far can we extrapolate? Is the effect of the chemical surface limited?

maandag 18 augustus 2014

When experts don't agree....

Nowadays in Europe OEL's for occupational exposure to genotoxic carcinogens are derived at a certain accepted risk level. That is how it is done in NL and also in Germany. In both countries the accepted risk level is 10EXP-6 per year = risk 4:100000 lifetime exposure. The (temperarily) tolerable risk level is 100 times higher.

However, recent published proposals of the Germany and of  NL show that German experts regard benzene as more toxic that NL Experts as can be seen from the proposed OEL's.

German Experts: Acceptable concentration associated with the risk 4:100000 = 0,2 mg/m3 , tolerable concentration associated with the risk 4:1000 = 1.9 mg/m3 ( TRGS 910: Risikobezogenes Maßnahmenkonzept für Tätigkeiten mit krebserzeugenden Gefahrstoffen. 2014).


The NL Committee of experts has concluded that benzene acts by a non-stochastic genotoxic mechanism. The Committee, therefore, decided to apply a threshold approach.recommends a health-based occupational exposure limit for benzene of 0.7 mg/m3  (Benzene. Health-based recommended occupational exposure limit.Dutch Expert Committee on Occupational Safety, a Committee of the Health Council of the Netherlands No. 2014/03, The Hague, February 21, 2014).

Buzzeling confusion. When leading experts don't agree, what should a simple consultant recommend?