Risk Assessment in the Federal Government Managing the Process Working Papers (1983) / Chapter Skim
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Formaldehyde
Formaldehyde
Pages 1-38
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Formaldehyde is sold mainly as an aqueous (water-based) solution called formalin, which is 37: to 50% formaldehyde by NOU: Thin case s Judy describes assessment procedures and summarizes issues and interpretations raised by others, but it is not intended to present independent pos itions or interpretations on either scienti fic or policy matters.
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After the llFFI is inside the wall, the insulation becomes firm or self-supporting. Formaldehyde that has not reacted with oilier chemicals after installation can eventually be released as formaldehyde gas.
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. Irritation ant Sens it ization Initial focus of attention to the possible health problems of UFFI began in October 1976, when the Metropolitan Denver District Attorney's Consumer Office filed a petition, requesting the Conquer Product Safety Commission (CPSC)
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formed the Formaldehyde Parcel, consisting of 16 federal scientists g charged -title reviewing and evaluating the avai late Le published and unpublished information including the ongoing CIIT study. In its final report to CPSC in November 1980, the panel concluded that it would be "prudent to regard formaldehyde as posing a carcinogenic risk to 'numans.
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I June 10, 1980 Action: CPSC issued a proposed rule to require manufacturers of UFFI to give information to prospective purchasers deco alert them to the possible adverse health effects associated with the release of formaldehyde gas from the product.
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April 2, 19~82 Action: CPSC issues a rule to ban ~FFI from residences and schoo l ~ in the U ~ S a CPSC withdraws proposed rule of June 10, 19800 CPSO denies Fo~aidehyde Institute petition of April 10, 1981 Deadlines: The bass is effective on or after August to, 1982 or the day after the expiration of the 90 calendar day period of continuing session of Congress following promulgation of the ban, whichever date is later. B IDENTIFICATION OF HAZA R33 O (determining the presence or absence of potential tonic effects)
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Review of the CIIT rat study began while it was still in progress. In January 1980, an I}lLO tack force was formed to verify the initial findings of CIIT and to ~ eek further informa ~ion.
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, found that fo~aidebyde was an animal carcinogen and that human exposures should be reduced or eliminated There were some limited human studies on industry workers and morticians. CESC found these to be inconclusive regarding their ability to predict human carcinogenic effects.
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The NAS study states, "As yet, there is no evidence of a population threshold for the irritant effects of formaldehyde in humans." The NAS leaves this question unresolved but advised maintaining "formaldehyde at the lowest practical concentration to minimize adverse effects on public health. " By the time NAS committee members wrote the final report, the preliminary results of the CIIT study were known.
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. Of negative results: The Formaldehyde Panel reached its conch u lion b seed ~~ the positive CIIT rat study as well as other supporting evidenced T.nis evidence included: ~ a)
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" (3) Findings of tissue damage and other effects in the inter~ _ preta~ion of tumor data: The Formaldehyde Panel considered both the irritation effects and the cytotoxic of feces of formaldehyde.
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. It toes imply that there is some histor;cal precedent within the federal agencies for the choices of inference options which the Formaldehyde Panel and CPSC applied to their risk as sessmer~ts .
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(3) Findings of tissue damage and other effects in the interpretat ion of tumor data: The author of this case study has found no specific reference in guidelines dealing with tissue damage and other toxic ef facts.
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In the opinion of another commenter, studies showed that there was no difference in formaldehyde levels between "properly foamed" homes and homes without UFFI. Care inogenic i ty Some conmenters stated that the CIIT rat study is flawed because formaldehyde exposure at L5 ppm caused ulceration and acute exudative inflammations which are in themselves cancer inducing.
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~ CPSC took the lead in developing a quantitative risk assessment which -~as reviewed and approved by other IRLG agencies. RAG hired a contractor to prepare and compile all the exposure data that was available for all possible areas of interest; i.e., occupational, drug related, environmental, and consumer.
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('~at additional data were sou'2ht? Animal Data The risk assessment utilized data exclusively from the CIIT rat srudyO Human Exposure There were two types o f human exposure data a One type was obtained from actual on-site measurement of UFFI and non-UFFI residences.
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Three different es titrates were given. Two of the estimates were based on the linearized multistage model of Crump, et al.
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~ The uncertainty in choosing an interspecies conversion factor was not accounted for in the CPSC risk assessment. Only one conversion factor was utilized.
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Both the Formaldehyde Panel and CPSC strongly endorsed the use of the linearized multistage model. This preference was based on their belief that it is the most Connie tent with prevalent theories on chemical carcinogenesis.
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(2) Choice of confidence limits or 'oest estimates: The l linearized multistage model utilized the 953 upper confidence limits Me purely statistical model utilized "maximum ike ~ ihood es time tes .
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was in accord with most guidelines developed by federal agencies in the past. The linearized multistage model, a sophisticated type of linear model, had been adopted by EPA' ~ Carcinogen Assessment Groups (CAG)
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" (5 ~ Treatment of data when data from more than one species or straits is available o Most agency guidelines written in the past have not explicitly addressed this questions The IRL& document, however, does False an explicit s tatement: "If data on animals are used as the basis for estimating human risk, data obtained from the most sensitive animal species or strain tested are commonly recommended as the starting point for extrapolation. Of the available data, these are clearly the least likely to underestimate human risks Use of data from less sensitive species or strains is justifiable only if there are strong reasons to believe that the moat sensitive animal model is completely irrelevant to any segment of the exposed human popula tion.
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One criticism dealt -with a refinement of the application of the linearized multistage model. In the initial rick assessment, the value of the upper 95: confidence limit of the lowest observed dose (2.
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CPSC' s had stated in its public record that effects due to formaldehyde on the nasal epithelia are observed at low doses. CPSC ci tes the occurrence o f benign tumors a t 2 ppm in the CT IT rat study, and the occurrence of nasal irritation effec ts at concentrations as tow as 00 25 ppm.
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There are scientific arguments which support the belief that genotoxic agents exhibit a linear nonthreshold response at the target s i te at low doses while nongenotoxic agents exhibit a threshold response . CPSC cons iders formaldehyde to be a geno toxic agent .
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chemical? The carcinogenic risk assess~sent ptayed a ~rital role in se~ting the final standard, which was to ban the use of 13FFI in residences and schools.
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No attempt was made, also, to address the question of mechanism of action or other physiological/ biochemical questions relevant to the extrapolation from rat to human even though such information was available from CIIT." He was also critical of the PRL-l treatment of the dose-response data from the CIIT rat ~ tudy . ''The risk ca lculat ion uset by OTS included the 5.6 ppm exposure level as a non-zero incidence data point.
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CPSC believes that formaldehyde is both an initiator and a promoter and that the reversibility and promotional aspect ~ points 1 and 4) do not argue against linearity at low doses especially when the property of initiation is CONS idered O CPSC further be lieves that tile absence of cytotoxic effects at loO ppm has not been at all demonstrated;
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also draws a distinction between benign and malignant growths by use of the term "cancer" rallier than "tumors.'' The CPSC risk assessment did not consider benign tumors, mainly because the information regarding their inc idence was not reported to CPSC by CIIT at the time. CPSC 's risk assessment does state, however, that inclusion of benign tumor data would lead to an increas ed pred ic t ion o f ris k.
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In the view of the author of this case study, many of the issues and concerns about the risk assessment of formaldehyde revolved around a complicated mix of risk assessment policy judgments and scientific judgments. On both s ides of the debate, there was often no clear distinction drawn between scientific and policy judgments O At the time the risk assessment was prepared, there were no uniform federal guidelines for carcinogenic risk assessment irt use.
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Hazard Ident if ic at ion The Formaldehyde Panel, IARC, NIOSH, the Sel ikof ~ and Hammond Committee Report to the American Cancer Society, the heads of NCI, NIEHS, and NCTR and three distinguished scientists at New York University Medical Center have all concurred that formaldehyde is a definite animal c arc inogen and should be cons idered to pose a human carcinogenic risk. Some interested parties could dispute these assertions, but it is likely that most would not.
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Characterization of Risk to Humans Seven CPSC staff persons worked full or part-time over two years collecting and reviewing data and reviewing comments. Me cancer risk assessment document (excluding the effort needed to obtain exposure data)
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Public hearings were 'nerd from December 1979 through February 1980 as industry, state and local government officials, scientists, and others testified on the question of UFFI ant formaldehyde release. As a result of all this activity, on June 10, 1980, CPSC issued ~ proposed rule '.~ch would require UFFI manufacturers to label their products giving specified performance and technical information to prospective purchasers.
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S ma jar areas of uncertainty affecting the resmelts of quantitative risk assessment are choice of the low dose extrapolation model and choice of the interspecies conversion factor.
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Hazard Identification lye Formaldehyde Panel, in its appraisal of formaldehyde as a potential l`uman carcinogen, appeared to be acting entirely independent ty o f agency regulators . Characterize ion of Rick CPSC appears to 'nave organizational separation between the assessors and the regulators.
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~ fortran program to extrapolate dichotomous animal carcinogeraicity data to low doses.
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S Consumer Product Safety Commission.
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