Daily Archives: August 17, 2011

Drinking Water Contamination at the Point-of-Use (or direct reuse?)

There are many possible sources of drinking water contamination that could occur at the point of use.  Including some that are very devious and intentional (with a very high yuck factor): Click here for an example from Singapore.

A target for Cr-VI toxic tort litigation

An airbone release of Cr-VI occurred in Stockton, New South Wales, Australia. The culprit this time was an Orica ammonium nitrate plant. I’d say that probably makes Orica the next target for Cr-VI toxic tort litigation. Click here for more.

The USEPA IRIS Reference Concentration (RfC) levels for inhalation of Cr-VI (below or click here) are based on chronic exposure. The risk associated with a very low short-term exposure is much less, if not negligible:

 

__I.B.1. Inhalation RfC Summary

 

Critical Effect Experimental Doses*
UF
MF
RfC
(1) Chromic acid mists and dissolved Cr (VI) aerosols:
Nasal septum atrophy

Human subchronic
occupational study
Lindberg and
Hedenstierna, 1983

NOAEL: none
LOAEL: 2E-3 mg/m3
7.14 E-4 mg/m3 (adj.)
90
1
8E-6
mg/m3
(2) Cr(VI) particulates:
Lactate dehydrogenase
in bronchioalveolar
lavage fluid

Rat subchronic study

Glaser et al., 1990
Malsch et al., 1994

BMD: 0.016 mg/m3
0.034 mg/m3 (adj.)
300
1
1E-4
mg/m3

 

 *Conversion Factors and Assumptions — Breathing rate for 8-hour occupational exposure = 10 m3; breathing rate for 24-hour continuous exposure = 20 m3; occupational exposure = 5 days/week; continuous exposure = 7 days/week. RDDR (regional deposited dose ratio for particulates to account for differences between rats and humans) = 2.16