Wednesday, 8 February 2012

RoHS – Register of Hazardous Substance

RoHS – Register of Hazardous Substance is an international requirement of the Occupational Safety and Health regime. The six substances are under strict scrutiny. Here we’ll recapture these substances and discuss their properties in brief. Mostly thanks to Wikipedia for facilitating my work.

Lead (play /ˈlɛd/) is a main-group element with the symbol Pb (from Latin: plumbum) and atomic number 82. Lead is a soft, malleablepoor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed to air. Lead has a shiny chrome-silver luster when it is melted into a liquid. Lead is used in building construction, lead-acid batteries, bullets and shots, weights, as part of solders, pewters, fusible alloys and as aradiation shield. Lead has the highest atomic number of all of the stable elements, although the next higher element, bismuth, has a half-life that is so long (much longer than the age of the universe) that it can be considered stable. Its four stable isotopes have 82protons, a magic number in the nuclear shell model of atomic nuclei.
Lead, at certain exposure levels, is a poisonous substance to animals. It damages the nervous system and causes brain disorders. Excessive lead also causes blood disorders in mammals. Like the element mercury, another heavy metal, lead is a neurotoxin that accumulates both in soft tissues and the bones. Lead poisoning has been documented from ancient Rome, ancient Greece, and ancient China.

Mercury (play /ˈmɜrkjəri/ or /ˈmɜrkəri/) is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver (play /ˈkwɪksɪlvər/ ) or hydrargyrum (play /haɪˈdrɑrdʒɨrəm/), from "hydr-" water and "argyros" silver. Mercury is the only metal that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine. With a freezing point of −38.83 °C and boiling point of 356.73 °C, mercury has one of the narrowest ranges of its liquid state of any metal. A heavy, silvery d-block metal, mercury is the only metallic element that is liquid at room temperature and standard pressure, with elements such as caesium, francium, gallium, and rubidium being liquid just above room temperature or at non-standard pressure.[1][2][3]
Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is mostly obtained by reduction from cinnabar. Cinnabar is highly toxic by ingestion or inhalation of the dust. Mercury poisoning can also result from exposure to water soluble forms of mercury (such as mercuric chloride or methylmercury), inhalation of mercury vapor, or eating seafood contaminated with mercury.
Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, some electrical switches, and other scientific apparatus, though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alcohol-filled, digital, or thermistor-based instruments. It remains in use in scientific research applications and in amalgam material for dental restoration. It is used in lighting: electricity passed through mercury vapor in a phosphor tube produces short-wave ultraviolet light which then causes the phosphor to fluoresce, making visible light.

Cadmium (play /ˈkædmiəm/ kad-mee-əm) is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low melting point compared to transition metals. Cadmium and its congeners are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in the Earth's crust is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate.
Cadmium occurs as a minor component in most zinc ores and therefore is a byproduct of zinc production. It was used for a long time as a pigment and for corrosion resistant plating on steel while cadmium compounds were used to stabilize plastic. With the exception of its use in nickel-cadmium batteries and cadmium telluride solar panels, the use of cadmium is generally decreasing in its other applications. These declines have been due to competing technologies, cadmium’s toxicity in certain forms and concentration and resulting regulations.[2] Although cadmium has no known biological function in higher organisms, a cadmium-dependent carbonic anhydrase has been found in marine diatoms.

Hexavalent chromium (chromium VI) refers to chemical compounds that contain the element chromium in the +6 oxidation state. Virtually all chromium ore is processed via hexavalent chromium, specifically the salt, sodium dichromate. Approximately 136,000,000 kilograms (300,000,000 lb) of hexavalent chromium were produced in 1985.[1] Other hexavalent chromium compounds are chromium trioxide and various salts of chromate and dichromate. Hexavalent chromium is used for the production of stainless steel, textile dyes, wood preservation, leather tanning, and as anti-corrosion and conversion coatings as well as a variety of niche uses. Chromium hexavalent (CrVI) compounds, often called hexavalent chromium, exist in several forms. Industrial uses of hexavalent chromium compounds include chromate pigments in dyes, paints, inks, and plastics; chromates added as anticorrosive agents to paints, primers, and other surface coatings; and chromic acid electroplated onto metal parts to provide a decorative or protective coating. Hexavalent chromium can also be formed when performing "hot work" such as welding on stainless steel or melting chromium metal. In these situations the chromium is not originally hexavalent, but the high temperatures involved in the process result in oxidation that converts the chromium to a hexavalent state.(29 CFR OSHA General Industry 1910)
Hexavalent chromium is recognized as a human carcinogen via inhalation.[2] Workers in many different occupations are exposed to hexavalent chromium. Problematic exposure is known to occur among workers who handle chromate-containing products as well as those who perform welding, grinding, or brazing on stainless steel.[2] Within the European Union, the use of hexavalent chromium in electronic equipment is largely prohibited by the Restriction of Hazardous Substances Directive.

Polybrominated biphenyls (PBBs), also called brominated biphenyls or polybromobiphenyls, are a group of manufactured chemicals, of the polyhalogenated compounds. Their chlorine analogs are the PCBs. While once widely used commercially, PBBs are now controlled substances under the Restriction of Hazardous Substances Directive, which limits their use in electrical and electronic products sold in the EU. PBBs are used as flame retardants of the brominated flame retardant group. They are added to plastics used in products such as home electrical appliances, textiles, plastic foams,laptop cabinets, etc. to make them difficult to burn.

Early studies on the effects of PBBs on human beings concerned the people in Michigan, USA who consumed PBB-contaminated animal products (see history of PBBs below).[2] A study of 327 girls aged 5–24 years in Michigan found those who were exposed in utero to PBBs at or above a level of 7 ppb found had an earlier age at menarche compared to a case-control group.[3] Michigan dairy farmers exposed to PBBs had significant immune system abnormalities including reduced numbers of circulating blood lymphocytes, increases in lymphocytes with no detectable surface markers, and reduced functional response to specific test antigens.[4] Some residents complained of nausea, abdominal pain, loss of appetite,joint pain and lethargy, though it could not be clearly established that PBBs were the cause of these health problems. Workers who were exposed to PBB during PBB production suffered hypothyroidism,[5] although no deterioration in memory performance was found in PBB-exposed workers in tests conducted several years after final PBB exposure, and there was also no correlation of performance with PBB concentration.[6]
There is stronger evidence that PBBs may have caused skin problems, such as acne, in consumers of the contaminated food. Some workers exposed to PBBs by breathing and skin contact for days to months also developed acne.
Studies in animals exposed to large amounts of PBBs for a short period or to smaller amounts over a longer period show that PBBs can cause weight loss, skin disorders, nervousand immune systems effects, as well as effects on the liver, kidneys, and thyroid gland.

Polybrominated diphenyl ethers or PBDE, are organobromine compounds that are used as flame retardants. Like other brominated flame retardants, PBDEs have been used in a wide array of products, including building materials, electronics, furnishings, motor vehicles, airplanes, plastics, polyurethane foams, and textiles. They are structurally akin to the PCBs and other polyhalogenated compounds, consisting of two halogenated aromatic rings. PBDEs are classified according to the average number of bromine atoms in the molecule. The health hazards of these chemicals have attracted increasing scrutiny, and they have been shown to reduce fertility in humans at levels found in households.[1] Their chlorine analogs are polychlorinated diphenyl ethers (PCDEs). Because of their toxicity and persistence, their industrial production is to be eliminated under the Stockholm Convention, a treaty to control and phase out major persistent organic pollutants (POP).
Since the 1990s, scientists have questioned the safety of PBDEs. People are exposed to low levels of PBDEs through ingestion of food and by inhalation. PBDEs bioaccumulate in blood, breast milk, and fat tissues. Personnel associated with the manufacture of PBDE-containing products are exposed to highest levels of PBDEs. Bioaccumulation is of particular concern in such instances, especially for personnel in recycling and repair plants of PBDE-containing products. People are also exposed to these chemicals in their domestic environment because of their prevalence in common household items. Studies in Canada have found significant concentrations of PBDEs in common foods such as salmon, ground beef, butter, and cheese.[3] PBDEs have also been found at high levels in indoor dust, sewage sludge, and effluents from wastewater treatment plants. Increasing PBDE levels have been detected in the blood of marine mammals such as harbor seals.
There is also growing concern that PBDEs share the environmental long life and bioaccumulation properties of polychlorinated dibenzodioxins.[4
Special Discussion
As we now understood that all Hazardous Material whether raw materials, intermediate products or wastes are Environmental Aspects.
Hazardous substances are Environmental Aspects
These substances needs to be adequately addressed when establishing the environmental management system vis-a-vis ISO14001. 
I worry about some potential misinterpretation by those who don't have enough time to think what they read, of what is written in Guidance Clause A.6.1.2, paragraph 5 of the ISO14001:2015 which states .. " An organization does not have to consider each product, component or raw material individually to determine and evaluate their environmental aspects; it may group or categorize activities, products and services when they have common characteristics." Regrouping some manufacturing activities or processes scheme into one category say 'Production' is indeed a good summary but may lead to the omission or 'overlooking' of important environmental aspects. Hence, this task must be justified by experienced personnel. I hope this gets checked.

Author: Khalid Mohd Ariff