CALIFORNIA AIR RESOURCES BOARD
Lincoln Plaza
Auditorium, First Floor
400 "P" Street
Sacramento, CA
July 13, 1990
8:30 a.m.
AGENDA
Page No.
90-10-1 Public Hearing to Consider the Adoption of 001
a Regulatory Amendment Identifying Inorganic
Arsenic as a Toxic Air Contaminant.
90-10-2 Public Hearing to Consider the Adoption of 024
an Airborne Toxic Control Measure for Dioxins
Emissions from Medical Waste Incinerators.
ITEM NO.: 90-10-1
Proposed Identification of Inorganic Arsenic as a Toxic Air
Contaminant (Regulatory).
RECOMMENDATION
The ARB staff recommends that inorganic arsenic be identified as
a toxic air contaminant without a specified threshold exposure
level.
DISCUSSION
In accordance with the provisions of Health and Safety Code
Section 39650 et seq., the ARB staff, after consulting the
Department of Health Services (DHS), selected inorganic arsenic
for the Board's consideration for listing as a toxic air
contaminant. The staff selected inorganic arsenic because the
International Agency for Research on Cancer (IARC) has identified
inorganic arsenic as a known human carcinogen. In addition, the
US EPA lists inorganic arsenic as a "Hazardous Air Pollutant"
(HAP) and Health and Safety Code Section 39655 requires HAPs be
identified as toxic air contaminants.
As required by Health and Safety Code Section 39661, a report was
prepared jointly by the ARB and DHS staffs. This report reviewed
the exposure levels and health effects of exposure to inorganic
arsenic in California. Major sources of inorganic arsenic are:
wood and fossil fuel combustion, geothermal steam, and arsenical
pesticides and herbicides. It is highly mobile in the
environment and is not naturally removed or detoxified at a rate
that would significantly reduce public exposure. Exposure to
arsenic is associated with increased respiratory cancer; the DHS
staff concluded that the effect of combining smoking and arsenic
exposure is greater than additive and may be multiplicative.
The Scientific Review Panel (SRP), established by Health and
Safety Code Section 39670, reviewed the report. The SRP found
that the inorganic arsenic report is without serious deficiency
and submitted its written findings to the Board. The SRP has
recommended that the Board list inorganic arsenic by regulation
as a toxic air contaminant, and found that, based on available
scientific information, inorganic arsenic exposure does not have
a threshold below which carcinogenic effects are not expected to
occur.
The overall population-weighted average inorganic arsenic cancer
risk, based on current smoking levels in California, is estimated
to range from 4 to 6 potential deaths per million; for nonsmokers
the risk ranges from 0.8 to 2 potential deaths per million.
Lifetime exposure to the mean ambient outdoor air concentration
of 1.9 ng per cubic meter (California's population-weighted
average ambient concentration) for a population of 20.3 million
Californians could result in up to 130 excess potential cancers.
"Hot spot" exposure to airborne inorganic arsenic may increase
the risk of respiratory cancer. A one-month monitoring study in
1986 downwind of a lead smelter measured average inorganic
arsenic concentrations of 61 ng per cubic meter. If exposures to
these concentrations would continue unabated for a lifetime, as
many as 6 to 9 potential excess cancer deaths might occur among
the 725,000 persons residing nearby.
IMPACTS OF PROPOSED BOARD ACTION
The identification of inorganic arsenic as a toxic air
contaminant will not in itself have any environmental and
economic impacts. However, specific control measures may be
developed subsequent to identification and an analysis of
potential environmental and economic impacts will be included in
the consideration of such control measures.
ITEM NO.: 90-10-2
Proposed Control Measure for Dioxins Emissions from Medical Waste
Incinerators.
RECOMMENDATION
The staff recommends that the Board adopt the proposed airborne
toxic control measure for dioxins emissions from medical waste
incinerators. The staff further recommends that the Board direct
the Executive Officer to request that districts evaluate the need
on a case-by-case basis for further control of cadmium emissions
from medical waste incinerators, and direct the Executive Officer
to evaluate the need for a further control measure to reduce
cadmium emissions through waste minimization and segregation.
INTRODUCTION
In July 1986, the Board identified dioxins as toxic air
contaminants. The staff of the Air Resources Board, in
consultation with the air pollution control districts, have
ranked California dioxins source categories for control measure
development according to emissions and exposure potential.
Medical waste incinerators have been given high priority for
control measure development because: 1) medical waste
incinerators have the potential for the greatest individual risk
of all dioxins sources currently identified; 2) most of the
incinerators identified are uncontrolled, poorly operated and
maintained, and located in residential areas; and 3) emissions
testing results show that these incinerators are sources of other
pollutants including cadmium, benzene, polycyclic aromatic
hydrocarbons (PAHs), hydrochloric acid, and other metallic and
organic compounds.
Cadmium emissions occur due to the cadmium content of the waste
stream: it is used in the dyes for the red bags that store the
infectious waste and is also in some medical supplies such as
plastic materials and batteries which eventually end up in these
incinerators.
SUMMARY
Dioxins are formed as products of incomplete combustion during
medical waste incineration. The proposed control measure would
reduce overall dioxins emissions by 99 percent, thereby reducing
the maximum individual risk of 1 to 250 in a million to less than
1 to 3 in a million for the current range of facilities that
decide to retrofit with control equipment. This measure would
also reduce the potential for acute health effects from
hydrochloric acid emissions, and reduce cadmium, benzene and PAH
emissions. The risk from dioxins and other emissions would be
eliminated completely from facilities that choose to cease
incinerator operation and convert to steam sterilization. The
total annualized cost of this control measure is estimated to
range from $3.2 to $6.1 million).