Is Chloroform Banned In India

[Rachelle Kun]

Chloroformis used as a solvent and in the production of other chemicals. Its use as the feedstock for polytetrafluoroethylene and other fluoropolymers is increasing at approximately 4-6% per year. Significant releases of chloroform arise indirectly through reactions of chlorine with organic chemicals and as a by-product during the addition of chlorine to drinking water and wastewaters for disinfection. Although no manufacturing occurs in Canada, chloroform may still enter the environment through use and from deliberate and accidental release, as well as from long-range transport.

The majority of environmental releases of chloroform are to the atmosphere. In the troposphere, chloroform may be degraded by reaction with hydroxyl radicals or transported to the surface via washout. Chloroform released to surface waters or soil will be transported to the air because of its high volatility. It does not partition significantly from air to soils, sediments or tissues because of its low affinity for organic carbon and lipids. Chloroform may be quite persistent in groundwater because volatilization is limited, as there is no contact with air, and biodegradation is slow under anaerobic conditions and almost non-existent under most aerobic conditions. Chloroform does not appear to bioconcentrate in aquatic organisms to any significant extent, an observation that is consistent with its octanol/water partition coefficient (log Kow = 1.97).

Data on toxicity are available for microorganisms, algae, aquatic invertebrates, fish, amphibians and laboratory mammals. No data on toxicity were identified for birds or wild mammals. Chloroform in Canadian air, surface water and groundwater does not appear to pose significant risks to populations of terrestrial wildlife or aquatic biota.

Chloroform is not an effective agent of stratospheric ozone depletion, since net chlorine loading in the stratosphere from the substance itself and its degradation products is small. Chloroform does not contribute significantly to climate change or to ground-level ozone formation.

The general population in Canada is exposed to chloroform principally through inhalation of indoor air and ingestion of tap water. Estimated intake from a single daily 10-minute shower exceeds that from all other exposure pathways.

Chloroform has induced liver tumours in mice and renal tumours in mice and rats. The weight of evidence, which is strongest for hepatic and renal tumours in mice and more limited for renal tumours in rats, indicates that chloroform may be carcinogenic only at concentrations that induce the obligatory precursor lesions of cytotoxicity and proliferative regenerative response. This cytotoxicity is primarily related to rates of formation of reactive, oxidative metabolites, principally phosgene.

Non-cancer effects observed most consistently at lowest concentrations or doses following repeated exposures of rats and mice to chloroform are sustained cytotoxicity and persistent regenerative proliferation. As for cancer, target organs are the liver (centrilobular region) and kidney (cortical region). In addition, chloroform has induced nasal lesions in rats and mice exposed by both inhalation and ingestion at lowest concentrations or doses.

Modelled tissue dose measures for a 24-hour exposure scenario for the general population of Canada are less than those associated with values considered appropriate as Tolerable Concentrations/Doses for cancer and non-cancer effects. A Tolerable Concentration is the level to which it is believed a person may be exposed daily over a lifetime without deleterious effect.

Based on the information available, it is concluded that chloroform is not entering the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity; constitute or may constitute a danger to the environment on which life depends; or constitute or may constitute a danger in Canada to human life or health. Therefore, chloroform is not considered to be "toxic" as defined in Section 64 of the Canadian Environmental Protection Act, 1999 (CEPA 1999), and evaluation of options under CEPA 1999 to reduce exposure is not considered a priority at this time. However, this is based on current use patterns; thus, future releases of this compound should continue to be monitored to ensure that exposure does not increase to any significant extent.

In view of the fact that showering is estimated to be the single greatest contributor to total daily intake of chloroform from drinking water, measures to reduce uptake from this source will be most effective in minimizing exposure of the general public.

The Canadian Environmental Protection Act, 1999 (CEPA 1999) requires the federal Ministers of Environment and of Health to prepare and publish a Priority Substances List (PSL) that identifies substances, including chemicals, groups of chemicals, effluents and wastes, that should be given priority to determine whether they are harmful to the environment or constitute a danger to human health. The Act also requires both Ministers to assess these substances and determine whether they are "toxic" or are capable of becoming "toxic" as defined in Section 64 of the Act, which states:

Substances that are assessed as "toxic" as defined in Section 64 may be placed on Schedule I of the Act and considered for possible risk management measures, such as regulations, guidelines, pollution prevention plans or codes of practice to control any aspect of their life cycle, from the research and development stage through manufacture, use, storage, transport and ultimate disposal.

Based on an initial screening of readily accessible information, the rationale for assessing chloroform provided by the Ministers' Expert Advisory Panel on the Second Priority Substances List (Ministers' Expert Advisory Panel, 1995) was as follows:

Chloroform is present in drinking water, food and indoor and outdoor air. Chloroform is imported for a variety of industrial applications and is generated in large quantities as a byproduct of water chlorination.

Most environmental releases from industrial uses are to the atmosphere. Chloroform is carcinogenic and genotoxic in animals and there is some evidence that it is carcinogenic in humans. Information on this substance has been gathered, reviewed and evaluated by an international group of experts. An assessment is needed to characterize the level of exposure and the associated risks to human health and the environment in Canada.

Descriptions of the approaches to assessment of the effects of Priority Substances on the environment and human health are available in published companion documents. The document entitled "Environmental Assessments of Priority Substances under the Canadian Environmental Protection Act. Guidance Manual Version 1.0 - March 1997" (Environment Canada, 1997a) provides guidance for conducting environmental assessments of Priority Substances in Canada. This document may be purchased from:

It is also available on the Commercial Chemicals Evaluation Branch web site at www.ec.gc.ca/cceb1/ese/eng/esehome.htm under the heading "Guidance Manual." It should be noted that the approach outlined therein has evolved to incorporate recent developments in risk assessment methodology, which will be addressed in future releases of the guidance manual for environmental assessments of Priority Substances.

The approach to the assessment of effects on human health is outlined in the following publication of the Environmental Health Directorate of Health Canada: "Canadian Environmental Protection Act - Human Health Risk Assessment for Priority Substances" (Health Canada, 1994), copies of which are available from:

or on the Environmental Health Directorate publications web site (www.hc-sc.gc.ca/ehp/ ehd/catalogue/bch.htm). The approach is also described in an article published in the Journal of Environmental Science and Health -Environmental Carcinogenesis & Ecotoxicology Reviews (Meek et al., 1994). It should be noted that the approach outlined therein has evolved to incorporate recent developments in risk assessment methodology, which are described on the Environmental Substances Division web site and which will be addressed in future releases of the approach paper for the assessment of effects on human health.

The search strategies employed in the identification of data relevant to assessment of potential effects on the environment (prior to July 1999) and human health (prior to October 1999) are presented in Appendix A. Review articles were consulted where appropriate. However, all original studies that form the basis for determining whether chloroform is "toxic" under CEPA 1999 have been critically evaluated by staff of Environment Canada (entry and environmental exposure and effects) and Health Canada (human exposure and effects on human health).

The environmental sections of this report were produced by D. Moore and L. Pirie of the Cadmus Group, Inc. on behalf of Environment Canada and were revised by D. Caldbick and K. Taylor, Environment Canada. They were reviewed by the following members of the Environmental Resource Group, established by Environment Canada to support the environmental assessment:

Environmental sections of the Assessment Report and the environmental supporting documentation (Environment Canada, 1999a) were also reviewed by internal reviewers at Environment Canada - namely, P. Cureton and D. Dub - as well as by external reviewers:

The health-related sections of this Assessment Report are based in part on the deliberations of two expert groups, in which staff of Health Canada participated. These were a Task Group on chloroform of the International Programme on Chemical Safety (IPCS) (WHO, 1994) and an Expert Panel convened by the International Life Sciences Institute (ILSI) to develop case studies for chloroform and dichloroacetic acid in the context of the revised cancer guidelines released in 1996 by the U.S. Environmental Protection Agency (EPA) (ILSI, 1997).

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