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The International Journal of Public Health

Statement WHO/1
(8 January 2001)

WHO'S RECOMMENDATION CONCERNS MAXIMUM TOLERABLE DAILY INTAKE OF DIOXINS, NOT SALMON

Severalrecent news reports about farmed salmon have incorrectly conveyed the recommendation of the World Health Organziation (WHO). They have stated that WHO reviewed new data on levels of dioxins in salmon and subsequently lowered its "recommended daily intak of salmon." This needs to be clarified.

WHO has never recommended a daily intake for salmon. Furthermore, WHO has not recived or reviewed the purported data showing higher levels of chemicals, including dioxins, in farmed salmon compared to wild varieties.

In 1998, WHO lowered its recommended Tolerable DAily Intake (TDI) of dioxins and related compounds such as, dibenzofurans and dioxin-like polychlorinated biphenyls (PCBs), to 1-4 picograms/kilogram body weight from 10 picograms/kilogram body weight. This reduced recommended TDI was based mainly on new information on the toxicity of these compounds, rather than on exposure considerations.

WHO will again examine the safety of dioxins and related compounds when the Joint United Nations Food and Agriculture Organization/ WHO Expert Committee on Food Additives (JECFA) meets in June 2001. JECFA welcomes the submission of any data on dioxins in food, including farmed and wild salmon, for evaluation by the JECFA experts.

Indoor air pollutants are an even greater threat to the health of millions. In developing countries, the domestic use of coal and biomass materials as fuel for heating and cooking is a major source of indoor pollution. The greatest threat in this case is to women and children living in poverty.

Air Pollutants

Air pollutants are classified as suspended particulate matter, gases and vapours that are presein the atmosphere in abnormally high concentrations.

• Particulate matter affects more people on continuing basis than any other pollutant. There are more monitoring data and epidemiological evidence available on particulate pollution exposure than on any other pollutant and its health effects.
• The main components of suspended particulate matter are coarse particles such as soil and mineral ash or fine particles found in wood smoke or coming from engine exhausts.
• Gaseous air pollutants are principally oxides of nitrogen (NO_X), ozone (O₃) carbon monoxide (CO), sulphur dioxide (SO₂), ammonia (NH₃) and volatile organic compounds.
• Other air pollutants include chlorinated fluorocarbons (CFCS) and other "greenhouse" gases, lead and other heavy metals and randon.

Trends

Concentrations of sulphur dioxide and suspended particulate matter are decreasing in developed countries, while those of NO_X and ozone are either constant or increasing. In developing countries, increasing traffic and its exhaust as well as industrial emissions are raising concentrations of SO₂, NO_X and O₃ and suspended particulate matter.

Ambient Air Pollution

Without proper controls, industry is a major source of air pollution. In this way, industrial operations can affect the health of workforces, the general environment and the health of nearby (and sometimes very far removed) populations.

• Particular industries with significant health impacts include: chemical, paper and pulp, cement, glass and ceramics, iron and steel, non-ferrous metals, leather, refining and processing petroleum, and particularly from coal and oil burning plants producing electric power.
• Motor vehicles account for about 30% of emissions of nitrogen oxides, 50% of hydrocarbons, 60% of lead and 60% of carbon monoxide in cities of developed countries. In city centres the values rise to 95% for carbon monoxide and up to 70% for nitrogen oxides.

Indoor Air Pollution

Even today, homes of the poor in developing countries are dangerous, unhealthy places - a rule of thumb states that a pollutant released indoors is 1000 times more likely to reach people's lungs than a pollutant released outdoors.

Some 2000 million people throughout the world use wood or other biomass fuels (cow dung, crop residues and grass) for cooking and heating. The domestic burning of these fuels is an inefficient process that produces many pollutants, some of which may be carcinogenic. The problems are worsened in areas where people spend most of their time indoors.

• A 20% reduction in indoor air pollution could reduce mortality from acute respiratory infection by at least 4-8 in some populations.

Coal burning for heating and cooking in developing countries results in indoor particle concentrations of up to 10,000 µg/m³, a level that is much higher even than ambient concentrations in polluted cities in Asia.

Pollution Control

Air pollution has long been associated with industrial processes and energy generation. Pollution control followed the European Industrial Revolution and increased in importance after World War II with economic expansion. Various steps have been taken to prevent the destruction of the environment and the removal or at least minimizing hazards to human health.

WHO's Response

Guidelines and Standards

WHO has produced the WHO Air Quality Guidelines. They are available from WHO or on the web site at: www.who.int/peh/air/airindex. The Guidelines provide background information, which enables countries to set their national or regional air quality standards in the context of existing environmental, social, economic and cultural conditions.

The Guidelines set out the range of ambient concentrations in exposure-response relationships and give guideline value; the air quality guideline value defines a concentration of air pollutant below which no adverse effect to human health is expected. Guideline values for 38 non-carcinogenic compounds and some carcinogens are set in relation to different exposure times. The table below gives some examples of the guideline value for common gaseous pollutants.

WHO Guidelines Values (1999) for Common Pollutants

Application of the WHO Air Quality Guidelines should help significantly to reduce the burden of excess mortality and preventable disability from a highly preventable source of ill-health.

Air Quality Management

For more than 20 years the WHO with the UN Environmental Programme (UNEP) assessed trends in ambient air pollution until this programme was replaced by the Air Management Information System (AMIS). Under the umbrella of WHO's Healthy Cities Programme, AMIS provides a means of actively sharing information between its members through as set of user-friendly databases. It is planned as a component of WHO's Global Air Quality Partnership, which brings together.

• UN agencies and programmes (e.g. WHO, UNEP and the UN Development Programme) as well as the World Bank and Regional Banks
• Regional Collaborating Centres
• national aid agencies (including those of Australia, Canada, Japan, Nordic countries and the USA)
• national Environmental Protection Agencies (including those of Canada, China, Germany, Japan and the USA)
• individual cities (a target of 300 has been set), such as Beijing, Bombay, Chicago, Jakarta, London, Manila, Mexico City and Santiago, and
• other bodies such as non-governmental organizations and the OECD
• Data on air pollution in cities are routinely collected and shared.
• A CD-ROM with data from more than 100 cities was published in 1998 and is being widely distributed
• Databases have been created on AMIS focal points, air pollution management capabilities and indoor air pollutant concentrations.