01-04-1994 - Vinyl Chloride Measurement for Risk vs. EnforcementCity of Win Covina
• • Memorandum
AGENDA.
To: City Manager
City Council ITEM NO. F
From: Environmental Services DATE .1-4-94
Director
Subject: Vinyl Chloride Measurement December 27, 1993
for Risk vs. Enforcement
SUMMARY: The Waste Management and Environmental Quality Commission
had information presented by the BKK Landfill Interagency
Steering Committee on the emissions and measurement of
vinyl chloride at the BKK Landfill: Some information was
presented that addressed the difference between measured
concentrations of vinyl chloride for Proposition 65 and
enforcement purposes.
On December 16, the Waste Management and Environmental Quality
Commission received the quarterly report from the BKK Landfill
Interagency Steering Committee. The emissions .of vinyl chloride
from the Landfill and its relationship to air quality enforcement
and Proposition 65 was discussed. An explanation of the different
purposes of Proposition 65 notification and enforcement and the
current concentration levels of vinyl chloride for these purposes
was discussed. The Commission voted to recommend to the City
Council that the City.request the appropriate agencies to provide
an explanation of the different concentration levels of vinyl
chloride for Proposition 65 notification purposes vs. enforcement
and other purposes.
The recent Proposition 65 notices placed in the newspaper by BKK
Corporation caused some discussion of the vinyl chloride emissions
at the Landfill. During the course of the regular BKK Landfill
Interagency Steering Committee .report some explanations were
provided on this subject. This discussion may be summarized as
follows:
1. The permitted concentration of vinyl chloride for
enforcement purposes is 10 parts per billion (ppb). This
concentration is normally only applied to.businesses that
use vinyl chloride in their operation and may have an
emission to control. The current AQMD regulation exempts
landfills. AQMD Staff has recommended this exemption be
removed.
2. The 10 ppb vinyl chloride concentration for enforcement
purposes was a level established by the California Air
Resources Board (GARB) in 1978. According to the State,
this level was established on the ability of equipment
and analysis procedures to'measure this level of vinyl
chloride.. According to the State this was the lowest
concentration that could be consistently measured by
equipment at 'the time. The AQMD is in the process of
reviewing this enforcement concentration level. They may
consider the lowering of this concentration level.
3. The 0.05 ppb.vinyl chloride concentration for the United
States Environmental Protection Agency's risk assessment
purposes is based on the number adopted by CARB in 1990.
This was done as a part of CARB's Toxic Air Contaminant
Program. The California Environmental Protection Agency,
Office of Environmental and Health Hazard Assessment
(OEHHA) estimated the carcinogenic potency of vinyl
chloride for.this Program.
4. The Proposition 65 warning level is based on the 0.05 ppb
level of concentration of vinyl chloride in the air.
According to the State the.Proposition 65 warning level
(the No Significant Risk Level) is set at l excess case
of cancer in 100,000 exposed individuals. Using.OEHHA's
potency value for vinyl chloride, the Proposition 65
warning level equates to 0.'05 ppb in ambient air (3
micrograms per day). According to the State this risk
estimate assumes a lifetime (70 years) exposure at this
concentration.
5. The difference between the.vinyl chloride concentration
used for enforcement and that level used for the risk
assessment and Proposition 65 is a'factor of 200. In
other words, 10 ppb concentration of vinyl chloride used
for enforcement is 200 times greater than the risk
assessment level of 0.05 ppb.
6. In between the extremes of 10 ppb and 0.05 ppb mentioned
above is the capability of equipment to measure these
concentrations. The agencies are of the opinion that no
one has the ability to consistently measure 0.05 ppb,
even with the most sophisticated equipment under very
controlled conditions in a laboratory. This relationship
between vinyl chloride concentrations and equipment can
be visually represented as follows:
10 parts per billion AQMD enforcement
concentration
---- Range in which
equipment in*the
field may measure
vinyl chloride
-- Range in which only
equipment in the
laboratory may
consistently
measure vinyl
chloride
0.05 parts per billion The concentration of
- vinyl chloride used.
by the ARB for
Proposition 65 based
on cancer risk
assessment
7. The background risk ,of developing cancer in our society
is around one person 'in a population of three. In other
words, one out every three.persons will develop cancer
during their. lifetime. To. place this in perspective,
there would be over 33,000 cases of cancer in a
population of 100,000 that.would equate to the background
risk level.
The above information has been presented at different times over
the last few years. This information was conveyed in oral and
written reports. However, most of the time the information was in
a technical context that may or may not have been understood by the
public.. In addition, the above information has never been put into
writing that would allow the public to read the description of the
various regulations and compare them to each other. It is this
lack of comparison that the Waste Management and Environmental
Quality Commission took their action. The Commission unanimously
recommends to the City Council that the City request the
appropriate agencies to provide an explanation of the different
concentration levels of vinyl chloride for Proposition 65
notification purposes vs. enforcement and other purposes.
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